Synergistic Manganese Cobalt Phosphide core-shell for the Electrochemical Detection of Methyl Parathion in Food Sample

The development of a robust electrocatalyst for the electrochemical sensor for hazardous pesticides will reduce its effects on the ecosystem. Herein, we synthesized the robust manganese cobalt phosphide (MnCoP) - Core-shell as an electrochemical sensor for the determination of hazardous pesticide methyl parathion (MP). The MnCoP- Core-shell was prepared with the sustainable self-template route can help with the larger surface area. The Core-shell structure of MnCoP possesses a higher active surface area which increases the electrocatalytic performance and is utilized to improve the electrochemical MP reduction with the synergism of the core and shell structure. Remarkably, it realizes the higher sensitivity (0.014 μA μM-1 cm-2) of MnCoP- Core-shell/GCE achieves towards MP with lower limit of detection (LoD 50 nM) and exceptional recovery rate of MP in vegetable samples are achieved with the differential pulse voltammetry (DPV) technique. The MnCoP- Core-shell electrode reserved their superior electrochemical performances with high reproducibility and repeatability. This prominent activity of the MnCoP core-shell towards the MP in real sample analysis, makes it a promising electrochemical sensor for the detection of MP.

Aluminum Phosphide Poisoning, an Institutional Experience: Case Series

BACKGROUND

The growing concern over pesticide use has been linked to self-harm and suicide especially in agricultural countries like Nepal.  Pesticides like organophosphorus and aluminum phosphide cause the majority of deaths. Although organophosphorus poisoning is common means for suicide, Aluminum phosphide poisoning is also encountered occasionally. Our case series aims to look after the intent of poisoning and the outcome of the patients following Aluminum phosphide poisoning.

METHODS

This hospital record-based study includes Aluminum phosphide poisoning patients presenting to the emergency department of Scheer Memorial Adventist Hospital from first January 2017 to 31st December 2020. Data were analyzed using SPSS version-22.

RESULTS

  Out of 25 total poisoning cases, most of them were female (60%) and married (56%).  The case fatality rate was 84% among which 20% cases were brought dead while 64% died in the hospital. All poisoning cases were suicidal in intent.

CONCLUSIONS

Herein we report a case series on 25 Aluminum phosphide poisoning cases with high case fatality rate and all cases being suicidal in intent.

Analysis of the Distribution of Total Phosphine and the Characteristics of Phosphine Poisoning in 29 Victims

OBJECTIVES

To study the distribution of total phosphine in phosphine poisoning victims and summarize the characteristics of phosphine poisoning cases.

METHODS

The phosphine and its metabolites in the biological samples of 29 victims in 16 phosphine poisoning cases were qualified and quantified by headspace gas chromatography-mass spectrometry.

RESULTS

Five victims among 29 were poisoned by ingestion of aluminium phosphide and 24 by inhalation of phosphine gas. Phosphine metabolites were detected in the biological samples of 23 victims, and the concentrations of total phosphine in blood ranged 0.5-34.0 μg/mL. The total concentration of phosphine in liver tissue was up to 71.0 μg/g. Phosphine was not detected in the blood of the other six survived victims, which may be related to the small amount of phosphine exposure and the delay in blood sampling.

CONCLUSIONS

The total concentration of phosphine in blood and tissues caused by aluminum phosphine ingestion is higher than that caused by phosphine gas inhalation. The death cases of phosphine inhalation are characterized by long exposure time, repeated exposures and age susceptibility.

Analysis of the characteristics of phosphine production by anaerobic digestion based on microbial community dynamics, metabolic pathways, and isolation of the phosphate-reducing strain

Although phosphine is ubiquitously present in anaerobic environments, little is known regarding the microbial community dynamics and metabolic pathways associated with phosphine formation in an anaerobic digestion system. This study investigated the production of phosphine in anaerobic digestion, with results indicating that phosphine production mainly occurred during logarithmic microbial growth. Dehydrogenase and hydrogen promoted the production of phosphine, with a maximum phosphine concentration of 300 mg/m³. The abundance of Ruminococcaceae and Escherichia was observed to promote phosphine generation. The analysis of metabolic pathways based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) and the MetaCyc pathway database revealed the highest relative abundance of replication and repair in genetic information processing; further, the cofactor, prosthetic group, electron carrier, and vitamin biosynthesis were observed to be closely related to phosphine formation. A phylogenetic tree was reconstructed based on the neighbor-joining method. The results indicated the clear evolutionary position of the isolated Pseudescherichia sp. SFM4 strain, adjacent to Escherichia, with a stable phosphate-reducing ability for a maximum phosphine concentration of 26 mg/m³. The response surface experiment indicated that the initial optimal conditions for phosphine production by SFM4 could be achieved with nitrogen, carbon, and phosphorus loads of 6.17, 300, and 10 mg/L, respectively, at pH 7.47. These results provide comprehensive insights into the dynamic changes in the microbial structure, isolated single bacterial strain, and metabolic pathways associated with phosphine formation. They also provide information on the molecular biology associated with phosphorus recycling.

Phosphine fumigation - Time dependent changes in the volatile profile of table grapes

Industrial and agricultural goods are fumigated in transport containers in order to control pest infestations and to avoid the transmission of alien species. Phosphine is increasingly used prior to the export as fumigant for table grapes, fruit cultures and dried fruits to control active table grapevine insect pests. Less knowledge exists for fumigants about the desorption time of toxic gases and factors that affect the composition of the fumigated good. Therefore, red and white table grapes (´Thompson seedless´, ´Scarlotta´ and ´Flame seedless´) were chosen to represent the allowed group of phosphine fumigated foods and were treated with a concentration of 2000 vpm phosphine (PH₃) at different temperatures. In the present study, sorption and desorption behavior of PH₃ by table grapes and possible changes in their VOC (volatile organic compounds) profiles were investigated. The PH₃ concentration was monitored before and after the fumigation process and was determined under the maximum residue level 0.005 ppm after 35 days. The adsorbed amount of PH₃ was not influenced by fumigation parameters. For analysis of the influences on the volatile profile after fumigation, a headspace solid-phase micro-extraction coupled to gas chromatography mass spectrometry (HS-SPME-GC/MS) was used. Small differences in volatile profiles of fumigated and subsequently outgassed table grapes compared to non-fumigated table grapes could be observed. A slight influence on the aldehyde group directly after fumigation could be perceived by a decrease of hex-2-en-1-ol and 1- hexanol in PH₃-treated table grapes. The concentrations of both compounds increase again after completion of the desorption process. On the other hand terpenes are not significantly influenced by the fumigation process. Overall these changes are likely to affect table grape aroma characteristics directly after a treatment with PH₃ and it could be demonstrated that phosphine alters the volatile profile of fumigated table grapes qualitatively and quantitatively.

Equilibrium and site selective analysis for DNA threading intercalation of a new phosphine copper(I) complex: Insights from X-ray analysis, spectroscopic and molecular modeling studies

To clarify the interaction of phosphine copper(I) complex with DNA, our study reports the synthesis of a new phosphine copper(I) complex, along with a detailed analysis of the geometry characterization and its interaction with double-stranded DNA. The triclinic phase Cu(PPh₃)₂(L)(I) with a tetrahedral geometry was identified as the product of the reaction of copper(I) iodide with (E,E)-N,N'-1,2-Ethanediylbis[1-(3-pyridinyl)methanimine] ligand and triphenylphosphine by single-crystal X-ray analysis. Molecular interaction of the synthesized complex with the calf thymus deoxyribonucleic acid (ct-DNA) was investigated in the physiological buffer (pH 7.4) by multi-spectroscopic approaches associated with a competitive displacement towards Hoechst 33258 and methylene blue (MB) as groove and intercalator probes. The fluorescence and UV/Vis results detected the formation of a complex-DNA adduct in the ground-state with a binding affinity in order of 10⁴ M^-1, which is in keeping with both groove binders and intercalators. The thermodynamic parameters, ΔS⁰ = -200.31 ± 0.08 cal/mol·K and ΔH⁰ = -63.11 ± 0.24 kcal/mol, confirmed that the van der Waals interaction is the main driving force for the binding process. Moreover, the ionic strength and pH effect experiments demonstrated the electrostatic interactions between the complex and DNA is negligible. Analysis of the molecular docking simulation declared the flat (E,E)-N,N'-1,2-Ethanediylbis[1-(3-pyridinyl)methanimine] part of the complex was inserted between the sequential A…T/A…T base pairs, while the phosphine substituents were located in the groove, i.e. threading intercalation. Besides, the cytotoxicity of the complex against the MCF-7 human breast cancer cells was detected at IC50 = 10 μg/mL.

Phosphine detection in veterinary samples using headspace gas chromatography/tandem mass spectrometry with multiple reaction monitoring

RATIONALE

Determination of phosphine exposure from zinc or aluminum phosphide fumigants continues to be a routine analytical requirement in veterinary forensic toxicology. There is a need for a more reliable and specific method than simple gas chromatography/mass spectrometry (GC/MS) analysis of sample solvent extracts, as GC/MS of extracts on capillary columns used for general screens involves significant interference from air peaks.

METHODS

GC/MS/MS headspace analysis of acid-generated phosphine gas enabled study of the feasibility of devising multiple reaction monitoring (MRM) approaches to the determination of phosphine with greater specificity.

RESULTS

Collision-induced dissociation in GC/MS/MS showed that phosphine generated m/z 34 → 31, 32 and 33 ion transitions by sequential proton release as well as minor transitions m/z 34 → 47, 34 → 63 and 63 → 31.5 by intermolecular collisions and double charging. Study of the formation of these product ions enabled development of MRM settings for a highly useful headspace method for phosphine detection.

CONCLUSIONS

The method was validated over a working range of 5-100 ppm of phosphide generating phosphine gas which enabled retention of regular screen capillary columns without necessitating separation from air components. The method should have adequate sensitivity and reliability for veterinary toxicology laboratories confronting specimens from animals poisoned by crop fumigants.

Phosphine as a Biosignature Gas in Exoplanet Atmospheres

A long-term goal of exoplanet studies is the identification and detection of biosignature gases. Beyond the most discussed biosignature gas O₂, only a handful of gases have been considered in detail. In this study, we evaluate phosphine (PH₃). On Earth, PH₃ is associated with anaerobic ecosystems, and as such, it is a potential biosignature gas in anoxic exoplanets. We simulate the atmospheres of habitable terrestrial planets with CO₂- and H₂-dominated atmospheres and find that PH₃ can accumulate to detectable concentrations on planets with surface production fluxes of 10¹⁰ to 10¹⁴ cm^-2 s^-1 (corresponding to surface concentrations of 10s of ppb to 100s of ppm), depending on atmospheric composition and ultraviolet (UV) irradiation. While high, the surface flux values are comparable to the global terrestrial production rate of methane or CH₄ (10¹¹ cm^-2 s^-1) and below the maximum local terrestrial PH₃ production rate (10¹⁴ cm^-2 s^-1). As with other gases, PH₃ can more readily accumulate on low-UV planets, for example, planets orbiting quiet M dwarfs or with a photochemically generated UV shield. PH₃ has three strong spectral features such that in any atmosphere scenario one of the three will be unique compared with other dominant spectroscopic molecules. Phosphine's weakness as a biosignature gas is its high reactivity, requiring high outgassing rates for detectability. We calculate that tens of hours of JWST (James Webb Space Telescope) time are required for a potential detection of PH₃. Yet, because PH₃ is spectrally active in the same wavelength regions as other atmospherically important molecules (such as H₂O and CH₄), searches for PH₃ can be carried out at no additional observational cost to searches for other molecular species relevant to characterizing exoplanet habitability. Phosphine is a promising biosignature gas, as it has no known abiotic false positives on terrestrial planets from any source that could generate the high fluxes required for detection.

Optimization and Validation of HS-SPME-GCMS Method for Determination of Multifumigant Residues in Grain, Oilseeds, Nuts, and Dry Fruit

Background: Fumigants are approved in many countries and used to treat food, feed, and seed. The amount of residue that remains in fumigated materials is measured and reported. Objective: The optimization and validation of a high-sensitivity headspace solid-phase microextraction gas chromatograph mass spectrometer (HS-SPME-GCMS) method for determination of eight fumigant residues-phosphine, methyl bromide, cyanogen, sulfuryl fluoride, ethylene oxide, propylene oxide, ethyl bromide and ethyl formate-in a range of food matrices were developed. The food matrices included grain, oilseed, dried fruit, and nut. Methods: The new method was used to determine residue levels from a fumigant complex in food matrices by monitoring the change of the absorption of spiked standards and desorption of fumigant from fumigated samples. Results: Based on the observation, the process of physical sorption and chemisorption was defined. The equilibrium time of the sample analysis was chosen at 5 hours. The LODs of the fumigants were in the range of 0.03 to 1.99 ng/g. Response to a range of diluted authentic standards gave significant linear regressions (r² > 0.9983), and the RSDs were ≤8.7% at the 3 ng/g level of aged spiking standard, except for sulfuryl fluoride, for which the LOD was 1.99 ng/g and the RSD value was 39.7% (6.64 ng/g). Conclusions: The performance of the HS-SPME-GCMS method was more sensitive than the use of a gas syringe, except for sulfuryl fluoride. Highlights: An innovative multifumigant residue detection method based on HS-SPME sampling technology with gas chromatograph-mass selective detection (GC-MSD) analysis was established, including phosphine, methyl bromide, cyanogen, sulfuryl fluoride, ethylene oxide, propylene oxide, ethyl bromide, and ethyl formate; The first report of a sorption study of the process of physical sorption and chemisorption of residual fumigant in fruit and food matrices by an HS-SPME-GCMS method; Consider the effect of time on fumigant behavior in dried fruit, grain, and nut; The LODs of the fumigants were in the range of 0.03 to 1.99 ng/g.

New environmental model for thermodynamic ecology of biological phosphine production

We present a new model for the biological production of phosphine (PH₃). Phosphine is found globally, in trace amounts, in the Earth's atmosphere. It has been suggested as a key molecule in the phosphorus cycle, linking atmospheric, lithospheric and biological phosphorus chemistry. Phosphine's production is strongly associated with marshes, swamps and other sites of anaerobic biology. However the mechanism of phosphine's biological production has remained controversial, because it has been believed that reduction of phosphate to phosphine is endergonic. In this paper we show through thermodynamic calculations that, in specific environments, the combined action of phosphate reducing and phosphite disproportionating bacteria can produce phosphine. Phosphate-reducing bacteria can capture energy from the reduction of phosphate to phosphite through coupling phosphate reduction to NADH oxidation. Our hypothesis describes how the phosphate chemistry in an environmental niche is coupled to phosphite generation in ground water, which in turn is coupled to the phosphine production in water and atmosphere, driven by a specific microbial ecology. Our hypothesis provides clear predictions on specific complex environments where biological phosphine production could be widespread. We propose tests of our hypothesis in fieldwork.

Physical, chemical and biological behaviour of fumigants on cottonseed

Fumigation is required to protect cottonseed in storage and pre-shipment from insect pests and/or microorganisms. Fumigation of cottonseed with carbon disulphide (CS₂), carbonyl sulphide (COS), ethanedinitrile (C₂N₂), ethyl formate (EF), methyl bromide (MB) and phosphine (PH₃) showed that >85% of the fumigants disappeared within 5 h of exposure. COS maintained >20 mg L^-1 for 24 h. After 1 day of aeration, 75%-85% of the absorbed COS and MB and 20%-40% of the absorbed CS₂, EF and PH₃ were released from treated cottonseed. The fumigant residues were reduced by 80% for COS, 50% for EF or MB and 25% for CS₂ after 1 day of aeration. After 13 days of aeration, fumigant residues were reduced by 95% for MB, 65% for EF, 55% for CS₂ and to natural levels in the COS residue. Carbon disulphide, COS, PH₃, EF and C₂N₂ had no effect on the germination of cottonseed, but germination was reduced to 50% by MB. COS has potential as a fumigant for control of insect pests in cottonseed because it dissipates quickly and does not negatively impact germination. On the other hand, MB appears to strongly absorb and requires an extended period for residues to dissipate, and it negatively impacts germination.

Phosphine production in anaerobic wastewater treatment under tetracycline antibiotic pressure

The influence of tetracycline (TC) antibiotics on phosphine (PH₃) production in the anaerobic wastewater treatment was studied. A lab-scale anaerobic baffled reactor with three compartments was employed to simulate this process. The reactor was operated in a TC-absence wastewater and 250μg/L TC-presence wastewater for three months after a start-up period, respectively. The responses of pH, oxidation-reduction potential (ORP), chemical oxygen demand (COD), total phosphorus (TP), enzymes activity (dehydrogenase and acid phosphatase), and microbial community were investigated to reveal the effect of TC on PH₃ production. Results suggested that the dehydrogenase (DH) activity, acid phosphatase (ACP) activity and COD have positive relationship with PH₃ production, while pH, ORP level and the TP in liquid phase have negative relationship with PH₃ production. With prolonged TC exposure, decrease in pH and increase in DH activity are beneficial to PH₃ production, while decrease in COD and ACP activity are not the limiting factors for PH₃ production.

The combination of in silico and in vivo approaches for the investigation of disrupting effects of tris (2-chloroethyl) phosphate (TCEP) toward core receptors of zebrafish

Tris (2-chloroethyl) phosphate (TCEP), a substitute for brominated flame retardants (FRs) that have been phased out of use, is frequently detected in aqueous environments. However, previous studies on its endocrine disrupting effects have mainly focused on terrestrial mammals. Here, to comprehensively evaluate the potential adverse effects of TCEP on aquatic vertebrates, zebrafish was used as a model to examine developmental phenotypes. The underlying mechanisms of toxicity of TCEP were further explored using in silico and in vivo approaches. In vivo results demonstrated morphologic changes and mortalities of zebrafish when exposed to high concentrations (14,250 and 28,500 μg TCEP/L). In silico results showed that TCEP can bind to and interact with nuclear receptors with different patterns. The combination of in vivo and in silico analyses indicated that receptors can influence each other at the molecular level and that ER, ThR, RXR and RyR were the key receptors influencing the transcriptional pathways. Our results demonstrate that TCEP has adverse effects at relatively low concentrations by affecting key receptors and genes of vertebrates. These results exhibited the need for further studies to evaluate the potential health risks of TCEP to human infants/children due to its high concentration in Chinese rivers (up to 3700 ng/L) and potential for human exposure.

Electrospray ionization in the study of the interactions between cytotoxic phosphino Cu(I) complexes and selected amino acids and GlyGlyHis peptide model

Tetrahedral [Cu(P)₄][BF₄]-type complexes (P = tertiary phosphine) are a class of monopositively charged compounds that have shown notable antitumor activity in both in vitro and in vivo tests. This biological property appears to be related to the peculiar physicochemical characteristics of these compounds. Although thermodynamically stable, they are labile at micromolar concentrations. Such a behavior allows the Cu(I) ion in [Cu(P)_n]⁺ assemblies (n < 4) to interact with surrounding molecules, including the rich peptide/protein environment that metal complexes have to face in the physiological milieu on the way to tumor cells. The scope of this investigation was to study the interaction products that originate from the treatment in water/methanol mixtures of representative phosphino Cu(I) compounds with an excess of individual amino acids (AAs) selected on the basis of the donor atom likely involved in metal coordination (i.e. O-glycine, S-methionine and N-histidine). These interactions have been investigated in electrospray ionization mass spectrometry (ESI-MS), mainly in the positive ion mode [ESI(+)MS], and the interaction products have been characterized by sequential collisional experiments, performed by an ion trap instrument. Histidine and methionine, but not glycine, were able to mine Cu(I) from [Cu(P)_n]⁺ assemblies through the formation of mixed [Cu^I(P)(AA)]⁺ and eventually [Cu^I(AA)₂]⁺ adducts. The ability to substitute phosphine(s) by AAs and the strongest affinity for Cu(I) was proved by the study of the energetics of collisional-induced decomposition (CID) reactions [Cu^I(P)(AA)]⁺ → Cu^I(AA) + P]⁺. Among the investigated AAs, histidine displayed the strongest affinity for Cu(I). Transchelation of Cu(I) was similarly observed when [Cu(P)_n]⁺ species were treated with the model tripeptide GlyGlyHis (GGH), the most investigated member of the amino terminal Cu(II) and Ni(II) (ATCUN) peptide family. GGH was able to form robust metal adducts not only with Cu(II) and the related divalent Zn(II) and Ni(II) ions, but also with monovalent ions, including Cu(I) and Ag(I). CID pathways of [Cu^I(GGH)]⁺ and [Ag^I(GGH)]⁺ were qualitatively superimposable and proceeded through losses of neutral fragments. Similar losses of neutral fragments were observed from [Zn^II(GGH)] and [Ni^II(GGH)]. CID pathways of [Cu^II(GGH)]^-/+ adducts instead took place mainly through intramolecular electron-transfer reactions comprising the reduction of Cu(II) to Cu(I) and the formation of fragment radical cations.

Aluminum Phosphide Poisoning-Related Deaths in Tehran, Iran, 2006 to 2013

Metal phosphides such as aluminum phosphide are potent insecticides. This highly toxic substance is used for rice and other grains protection in Iran. Due to its high toxicity potential and easy availability, it is widely used as a suicide poison. This substance has no effective antidote and the incidence of deaths due to its poisoning is increasing day by day in Iran. The present study was conducted to show the increasing incidence of fatal aluminum phosphide poisoning and its toxicological and forensic aspects in an 8-year study, 2006 to 2013. Autopsy sheets were reviewed and cases with the history of aluminum phosphide poisoning were selected. Toxicological analysis results, demographic and necroscopic examination findings were studied. A total of 51.8% of studied cases were female. Most of the cases were between 10 and 40 years old. The manner of death was self-poisoning in 85% of cases. Morphine, ethanol, and amitriptyline were the most common additional drugs detected in toxicological analysis. The incidence of fatal aluminum phosphide poisoning cases referred for phosphine analysis was 5.22 and 37.02 per million of population of Tehran in 2006 and 2013, respectively. The results of this study showed that in spite of ban and restrictions, there was a dramatic increase in the incidence of fatal aluminum phosphide poisoning in Tehran from 2006 to 2013. Safety alert should be highlighted in training program for all population groups about the toxic effects of aluminum phosphide tablets.

Intentional fatal metallic phosphide poisoning in a dog--a case report

BACKGROUND

Metallic phosphides are extremely toxic pesticides that are regulated in their usage. Information concerning the impact of metallic phosphides on human health is abundant. Data regarding the clinical pathology of phosphide poisoning in humans or domestic and wild animals is largely incomplete with only a few cases of metallic phosphide poisoning being reported every year, especially in humans. For the majority of cases reported in dogs the data are vague or incomplete. Here we report a complete and detailed description of pathological changes in a case of intentional metallic phosphide poisoning in a dog including an exhaustive examination of the brain.

CASE PRESENTATION

A 1 year old, male, Belgian Shepherd crossbreed dog with a clean medical history and no observed clinical signs prior to death, was submitted for post mortem examination. The dog was found dead by the owner. Near the body a suspect mix of bread, fat and a blackish powder was found. The owner announced the authorities and submitted the animal and the possible bait for forensic examination. At necropsy, multisystemic necrotic and degenerative lesions were observed. Histological exam confirmed the presence of necrotic and degenerative lesions of variable severity in all of the examined organs. The toxicological forensic examination revealed the presence of the phosphine gas in the gastric content and the bait.

CONCLUSION

Metallic phosphide poisoning is a rarely reported entity, since the diagnosis of intentional poisoning with these compounds is a great challenge for forensic pathologists and toxicologists. To our knowledge, this is the first study describing the lesions completely in veterinary forensic toxicology. We assume that the toxic shows systemic endotheliotropism and damage of the endothelial cells responsible for the hemorrhagic lesions and for the secondary ischemic necrosis in various organs. This report will contribute to a better understanding of the pathogenesis in cases of acute metallic phosphide exposure in animals.

Re and (99m)Tc complexes of BodP3--multi-modality imaging probes

A fluorescent tridentate phosphine, BodP3 (2), forms rhenium complexes which effectively image cancer cells. Related technetium analogues are also readily prepared and have potential as dual SPECT/fluorescent biological probes.

Redox chemistry in the phosphorus biogeochemical cycle

The element phosphorus (P) controls growth in many ecosystems as the limiting nutrient, where it is broadly considered to reside as pentavalent P in phosphate minerals and organic esters. Exceptions to pentavalent P include phosphine--PH3--a trace atmospheric gas, and phosphite and hypophosphite, P anions that have been detected recently in lightning strikes, eutrophic lakes, geothermal springs, and termite hindguts. Reduced oxidation state P compounds include the phosphonates, characterized by C-P bonds, which bear up to 25% of total organic dissolved phosphorus. Reduced P compounds have been considered to be rare; however, the microbial ability to use reduced P compounds as sole P sources is ubiquitous. Here we show that between 10% and 20% of dissolved P bears a redox state of less than +5 in water samples from central Florida, on average, with some samples bearing almost as much reduced P as phosphate. If the quantity of reduced P observed in the water samples from Florida studied here is broadly characteristic of similar environments on the global scale, it accounts well for the concentration of atmospheric phosphine and provides a rationale for the ubiquity of phosphite utilization genes in nature. Phosphine is generated at a quantity consistent with thermodynamic equilibrium established by the disproportionation reaction of reduced P species. Comprising 10-20% of the total dissolved P inventory in Florida environments, reduced P compounds could hence be a critical part of the phosphorus biogeochemical cycle, and in turn may impact global carbon cycling and methanogenesis.

Regional distribution of halogenated organophosphate flame retardants in seawater samples from three coastal cities in China

Thirteen samples of seawater were collected from Yellow Sea and East China Sea near Qingdao, Lianyungang, and Xiamen, China. They were analyzed for halogenated organophosphorus flame retardants (OPFRs). The compounds selected for detection were Tris(2-chloroethyl) phosphate (TCEP), Tris(2-chloroisopropyl) phosphate (TCPP), Tris (1,3-dichloro-2-propyl) phosphate (TDCPP), and Tris(2,3-dibromopropyl) phosphate (TDBPP). The total concentrations ranged from 91.87 to 1392 ng/L and the mean concentrations of these four chemicals were 134.44, 84.12, 109.28, and 96.70 ng/L, respectively. TCEP exhibited the highest concentrations, although concentrations of TCPP and TDCPP were also fairly high in Lianyungang and Xiamen. Generally, Lianyungang was the most heavily polluted district, with very high concentrations of TCEP at LYG-2 (550.54 ng/L) and LYG-4 (617.92 ng/L). The main sources of halogenated OPFRs were municipal and industrial effluents of wastewater treatment plants in the nearby economic and industrial zones.

Matrix-bound phosphine, phosphorus fractions and phosphatase activity through sediment profiles in Lake Chaohu, China

The distribution patterns of matrix-bound phosphine (MBP), phosphorus (P) fractions and neutral phosphatase activity (NPA) were investigated through five sediment profiles in Lake Chaohu, China. MBP was discovered in all sediment profiles within the concentration range of 1.58-50.34 ng kg(-1). These concentrations exhibited a consistent vertical distribution pattern in all profiles, and higher concentrations generally occurred in surface sediments. MBP concentrations showed a significant positive correlation with P fractions, total nitrogen (TN), Cu and Zn under lower levels of inorganic phosphorus (<0.6 g kg(-1)), organic phosphorus (<0.2 g kg(-1)), TN (<0.13%), Cu (<25 mg kg(-1)) and Zn (<150 mg kg(-1)), but no statistically significant correlations were obtained under higher levels. A multiple stepwise regression model ([MBP]=1.36[NPA]-6.21[pH]-0.06[Zn]+0.75[Cu]+49.86) was obtained between MBP concentrations and environmental variables, and MBP concentrations showed a strong positive correlation with NPA (P<0.0001). This indicates that the production of sediment MBP was controlled by microbially mediated processes in Lake Chaohu. This model could be used to predict MBP levels in the sediments. Our results indicate that MBP levels could not be used as indicators for the degree of lake eutrophication. The study of sediment MBP, P factions and NPA will improve our understanding of P cycling and their environmental significance in the eutrophic Lake Chaohu.

Matrix-bound phosphine and phosphorus fractions in surface sediments of Arctic Kongsfjorden, Svalbard: effects of glacial activity and environmental variables

The surface sediments were collected from the glacial bay (GLAC), the central basin (CENTR) and their transition area (TRANS) along the fjord Kongsfjorden axis on Svalbard, Arctic, and matrix-bound phosphine (MBP), phosphorus fractions and alkaline phosphatase activity (APA) were analyzed. MBP was found in all the sediments with the concentration range of 8.93-59.45 ng kg(-1) dw. The MBP levels in the CENTR sediments were two times higher than those in the GLAC and TRANS sediments, and the yield of phosphine (PH3) as a fraction of total phosphorus ranged from 1.78×10(-8) to 3.53×10(-8) mg PH3 mg(-1)P. The CENTR and TRANS sediments showed higher concentrations of total phosphorus (TP), organic phosphorus (OP) and APA than the GLAC sediments, indicating that glacial activity had an important effect on the spatial variability in the concentrations of MBP and phosphorus fractions. There existed a significant positive correlation (p<0.01) between MBP and seawater depths, OP, TP, APA, total organic matter, total nitrogen and total sulfur. The multiple stepwise regression model ([MBP]=16.1[OP]+18.6[APA]-26.1pH+221.3) was obtained between MBP concentrations and environmental variables. This model could be used to predict MBP levels in the sediments. Our results indicated that the production of MBP was associated with OP decomposition and microbially mediated factors in the sediments of Kongsfjorden in Arctic.

Catalytic decomposition of toxic chemicals over iron group metals supported on carbon nanotubes

This study explores catalytic decomposition of phosphine (PH3) using iron group metals (Co, Ni) and metal oxides (Fe2O3, Co(3)O4, NiO) supported on carbon nanotubes (CNTs). The catalysts are synthesized by means of a deposition-precipitation method. The morphology, structure, and composition of the catalysts are characterized using a number of analytical instrumentations, including high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, BET surface area measurement, and inductively coupled plasma. The activity of the catalysts in the PH3 decomposition reaction is measured and correlated with their surface and structural properties. The characterization results show that phosphidation occurs on the catalyst surface, and the resulting metal phosphides act as an active phase in the PH3 decomposition reaction. Cobalt phosphide, CoP, is formed on Co/CNTs and Co(3)O4/CNTs, whereas iron phosphide, FeP, is formed on Fe2O3/CNTs. In contrast, phosphorus-rich phosphide NiP2 is formed on Ni/CNTs and NiO/CNTs. The initial activities of the catalysts are shown in the following sequence: Ni/CNTs > Co/CNTs > Co(3)O4/CNTs >NiO/CNTs > Fe2O3/CNTs, whereas activities of metal phosphides are shown in the following order: CoP > NiP2 > FeP. The catalytic activity of metal phosphides is attributed to their electronic properties. Cobalt phosphide formed on Co/CNTs and Co(3)O4/CNTs exhibits not only the highest activity, but also long-term stability in the PH3 decomposition reaction.

Determination of phosphine in plant materials: method optimization and validation in interlaboratory comparison tests

The optimization and validation of a method for the determination of phosphine in plant materials are described. The method is based on headspace sampling over the sample heated in 5% sulfuric acid. Critical factors such as sample amount, equilibration conditions, method of quantitation, and matrix effects are discussed, and validation data are presented. Grinding of coarse samples does not lead to lower results and is a prerequisite for standard addition experiments, which present the most reliable approach for quantitation because of notable matrix effects. Two interlaboratory comparisons showed that results varied considerably and that an uncertainty of measurement of about 50% has to be assessed. Flame photometric and mass spectrometric detection gave similar results. The proposed method is well reproducible within one laboratory, and results from the authors' laboratories using different injection and detection techniques are very close to each other. The considerable variation in the interlaboratory comparison shows that this analysis is still challenging in practice and further proficiency testing is needed.

Phosphine in paddy fields and the effects of environmental factors

Ambient levels of phosphine (PH3) in the air, phosphine emission fluxes from paddy fields and rice plants, and the distribution of matrix-bound phosphine (MBP) in paddy soils were investigated throughout the growing stages of rice. The relationships between MBP and environmental factors were analyzed to identify the principal factors determining the distribution of MBP. The phosphine ambient levels ranged from 2.368±0.6060 ng m(-3) to 24.83±6.529 ng m(-3) and averaged 14.25±4.547 ng m(-3). The highest phosphine emission flux was 22.54±3.897 ng (m(2)h)(-1), the lowest flux was 7.64±4.83 ng (m(2)h)(-1), and the average flux was 14.17±4.977 ng (m(2)h)(-1). Rice plants transport a significant portion of the phosphine emitted from the paddy fields. The highest contribution rate of rice plants to the phosphine emission fluxes reached 73.73% and the average contribution was 43.00%. The average MBP content of 111.6 ng kg(-1)fluctuated significantly in different stages of rice growth and initially increased then decreased with increasing depth. The peak MBP content in each growth stage occurred approximately 10 cm under the surface of paddy soils. Pearson correlation analyses and stepwise multiple regression analysis showed that soil temperature (Ts), acid phosphatase (ACP) and total phosphorus (TP) were the principal environmental factors, with correlative rankings of Ts>ACP>TP.

[Distribution of matrix-bound phosphine in surface sediments of Jinpu Bay]

This work investigated the distribution of matrix-bound phosphine in surface sediments of Jinpu Bay and associated environmental factors in summer, using the gas chromatography combined with a pulsed flame detector (GC-PFPD). It showed that phosphine ubiquitously presented in the sediments of Jinpu Bay. Contents of matrix-bound phosphine varied between 62. 58 and 190. 81 ng.kg-1, with the average value of 114.42 ng.kg-1. In addition, the spatial distribution of matrix-bound phosphine indicated that matrix-bound phosphine in inshore sediments had relatively higher contents than those in offshore sediments. Statistical analysis showed that matrix-bound phosphine significantly related to organic phosphorus and alkaline phosphatase activity ( R = 0. 882, P = 0. 01; R = 0. 819, P =0. 023). However, there were no correlations between matrix-bound phosphine and organic nitrogen, inorganic phosphorus and sediment grain sizes. These results implied that accumulation and distribution of matrix-bound phosphined were mainly affected by the decomposition of organic phosphorus by microorganisms.

Aggregation-induced emission of a novel conjugated phosphonium salt and its application in mitochondrial imaging

A new conjugated phosphonium salt TPP was synthesized readily from phosphine-triggered ring-opening of 2,4,5-triphenylpyrylium salt. In aqueous solution, it exhibited interesting AIEE properties and self-assembled into fluorescent nanoparticles, which can be used as a fluorescence probe to image mitochondria in cells.

Death by caffeine: presumptive malicious poisoning of a dog by incorporation in ground meat

BACKGROUND

A 4-year-old, 37 kg, male German shepherd developed hyperthermia, tachycardia, and agitation following consumption of ground meat found in the backyard of its owner. When presented to a veterinary clinic, plasma ethylene glycol (EG) testing was positive, and the dog was given ethanol and lactated Ringer's solution intravenously. Approximately 11 h postexposure the dog died.

DISCUSSION

Among tissues submitted for toxicological analysis, urine was negative for EG, ground meat was negative for certain drugs of abuse, and gastric contents were negative for zinc/aluminum phosphide and metaldehyde. Analysis of gastric contents by gas chromatography-mass spectrometry confirmed the presence of caffeine. Caffeine concentration in the ground meat was estimated at 1 %. Caffeine is a methylxanthine alkaloid with a reported canine oral median lethal dose (MLD(50)) of 140 mg/kg (range 120-200 mg/kg). A commercially available 200-mg tablet formulation of caffeine was considered to be a possible source but this was not confirmed. By conservative estimates, the dog would need to ingest approximately 500-550 g of the meat to reach the MLD(50). Acute intoxication affects the cardiovascular, pulmonary, neurologic, gastrointestinal, and metabolic systems. Although no tablet remnants were observed in the bait, tablets could have been crushed and/or dissolved. Other potential caffeine sources include guarana, brewed and concentrated coffee, and caffeine-containing beverages. Based on the history, clinical signs, and the detection of caffeine in the gastric contents and meat, a presumptive diagnosis of malicious caffeine poisoning was made. A suggested treatment regimen for caffeine intoxication in dogs is described. While few cases of accidental ingestion of caffeine by dogs have been described, the intentional use of a concentrated caffeine source to cause mortality in a dog has not been previously reported.

[Distributions of matrix-bound phosphine in surface sediments of the Yangtze Estuary]

Concentrations of matrix-bound phosphine (MBP) in the surface sediments of the Yangtze Estuary were investigated in the present study using gas chromatography coupled with a pulsed flame photometric detector (GC-PFPD), and the potential environmental factors were discussed. It was shown that the MBP concentrations were relatively higher in May than in November, with the ranges of 139-426 ng x kg(-1) and 111-192 ng x kg(-1), respectively. Also, there was the significant spatial difference in MBP concentrations at the study area. In addition, it was observed that MBP was significantly related to TP, IP, OP, pH, and activities of APA in the surface sediments. However, no significant correlations were found between MBP, organic carbon and salinity.

Occurrence of matrix-bound phosphine in polar ornithogenic tundra ecosystems: effects of alkaline phosphatase activity and environmental variables

Phosphine (PH(3)), a reduced phosphorus compound, is a highly toxic and reactive atmospheric trace gas. In this study, a total of ten ornithogenic soil/sediment profiles were collected from tundra ecosystems of east Antarctica and Arctic, and matrix-bound phosphine (MBP), the phosphorus fractions and alkaline phosphatase activity (APA) were analyzed. High MBP concentrations were found in these profiles with the range from 39.59 ng kg(-1) dw to 11.77 μg kg(-1) dw. MBP showed a consistent vertical distribution pattern in almost all the soil profiles, and its concentrations increased at soil surface layers and then decreased with depths. MBP levels in the ornithogenic soils were two to three orders of magnitude lower than those in ornithogenic sediments. The yield of PH(3) as a fraction of total P in all the profiles ranged from 10(-5) to 10(-9) mgPH(3) mg(-1)P with higher mean PH(3) yield in the ornithogenic sediments. The ornithogenic soils showed high concentrations of total phosphorus (TP), organic phosphorus (OP), inorganic phosphorus (IP) and metal elements (Cu, Zn, Mn, Fe, Al and Ca) but low MBP levels, vice versa for the ornithogenic sediments. No correlation had been obtained between MBP concentrations and IP, OP and TP. There existed an exponential correlation (r=0.67, p<0.01) between MBP and soil/sediment moisture. MBP concentrations showed a significant positive correlation with APA (r=0.668, p<0.0001), total organic carbon (r=0.501, p<0.0001), total hydrogen (r=0.483, p<0.0001) and total sulfur (r=0.398, p<0.001), indicating that the production of MBP is associated with microbially mediated factors rather than the contents of TP, IP and OP in the P-enriched ornithogenic soils/sediments. Our results indicated that MBP is an important gaseous link in the phosphorus biogeochemical cycles of ornithogenic tundra ecosystems in Antarctica and Arctic.

Surprises perilous: toxic health hazards for employees unloading fumigated shipping containers

The fumigation of freight containers to protect transported goods from fungal and pest infestation has increased worldwide in the last five years due to international regulations requiring fumigation or heat treatment of wooden packaging material and dunnage. We have found in 2008 that every sixth container and its contents do retain harmful concentrations of various fumigants and chemicals, representing a significant health risk for port and transport workers, customs officials, warehousemen, store employees and consumers. The shipping documents of these containers did not provide any information about the fumigation procedure or the used fumigant. We report here the cases of 26 patients introduced to our outpatient clinic with presumed intoxication to fumigants, or with symptoms due to inhaling the air out of fumigated containers. All patients were examined from 2007 to 2010 according to a standardized comprehensive diagnostic program. We were able to confirm the diagnosis based on typical symptoms and extensive clinical examination; by laboratory analysis we identified ethylene dichloride, methyl bromide, phosphine and methylene chloride. The predominant symptoms were headaches, concentration and memory problems, dizziness and nausea, irritation of the skin and mucous membranes and a reduced ability to do exercise. In addition to the neurological and neuropsychological impairments our analyses verified the development of reactive airways dysfunction syndrome (RADS) in 14 of 26 patients with long lasting symptoms due to their contact with fumigants. Intoxications with fumigants are serious and could be avoided. These systematical explored cases show the sustainable impact for health and socio-economic wellbeing. These findings also emphasize the necessity for international standards on permitted fumigants, appropriate labeling in the shipping documents and handling of fumigated containers.

Matrix-bound phosphine in sediments from Lake Illawarra, New South Wales, Australia

Matrix-bound phosphine (MBP) has been measured in sediment from two cores in Lake Illawarra on the south east coast of Australia. The sediments were also dated in the upper layers. MBP concentrations found range from 142 to 1813 ng kg(-1), dw (dry weight of sediment) with some values being amongst the highest ever measured. Values of MBP in deeper sediments were higher than for near surface samples, but the patterns with depth were not consistent. Strong correlations were noted between MBP and organic phosphorus (OP, r>0.8) and with total phosphorus (TP, r>0.7), but only moderate correlations were found with organic carbon (OC, r>0.5). No correlations were found between MBP concentrations and the age of the sediments. It was confirmed that high MBP concentrations are indicative of a phosphorus rich environment. The results tend to support the premise that MBP is generated by microbial attack on OP under anaerobic conditions.

Occurrence and suitability of sucralose as an indicator compound of wastewater loading to surface waters in urbanized regions

Urban watersheds are susceptible to numerous pollutant sources and the identification of source-specific indicators can provide a beneficial tool in the identification and control of input loads, often times needed for a water body to achieve designated beneficial uses. Differentiation of wastewater flows from other urban wet weather flows is needed in order to more adequately address such environmental concerns as water body nutrient impairment and potable source water contamination. Anthropogenic compounds previously suggested as potential wastewater indicators include caffeine, carbamazepine, N,N-diethyl-meta-toluamide (DEET), gemfibrozil, primidone, sulfamethoxazole, and TCEP. This paper compares the suitability of a variety of anthropogenic compounds to sucralose, an artificial sweetener, as wastewater indicators by examining occurrence data for 85 trace organic compounds in samples of wastewater effluents, source waters with known wastewater point source inputs, and sources without known wastewater point source inputs. The findings statistically demonstrate the superior performance of sucralose as a potential indicator of domestic wastewater input in the U.S. While several compounds were detected in all of the wastewater effluent samples, only sucralose was consistently detected in the source waters with known wastewater discharges, absent in the sources without wastewater influence, and consistently present in septic samples. All of the other compounds were prone to either false negatives or false positives in the environment.

Influences of sediment dessication on phosphorus transformations in an intertidal marsh: formation and release of phosphine

This study investigated the effects of sediment dewatering on the phosphorus transformations concerning about the production and emission of phosphine in the intertidal marsh of the Yangtze Estuary. The concentrations of matrix-bound phosphine ranged from 18.62-72.53 ng kg(-1) and 31.14-61.22 ng kg(-1) within the August and January exposure incubations, respectively. The responses of matrix-bound phosphine concentrations to sediment dessication demonstrate that the production (or accumulation) of matrix-bound phosphine significantly increased with water loss at the start of the emersion incubations. However, further dehydration inhibited the formation of matrix-bound phosphine in sediments. The significant correlations of matrix-bound phosphine with the organic-P bacteria abundance and alkaline phosphatase activities implicate that the production of matrix-bound phosphine within the dessication incubations was linked closely to the microbial decomposition of organic P. The emissions of phosphine generally decreased with sediment dewatering, with the fluxes of 7.51-96.73 ng m(-2)h(-1) and 5.34-77.74 ng m(-2)h(-1) over the exposure incubations of both August and January, respectively. Also, it is observed that the releases of phosphine during the entire exposure periods were affected not only by its production but also by sediment water and redox conditions.

Free atmospheric phosphine concentrations and fluxes in different wetland ecosystems, China

Atmospheric phosphine (PH(3)) fluxes from typical types of wetlands and PH(3) concentrations in adjacent atmospheric air were measured. The seasonal distribution of PH(3) in marsh and paddy fields were observed. Positive PH(3) fluxes are significantly related to high air temperature (summer season) and increased vegetation. It is concluded that vegetation speeds up the liberation of PH(3) from soils, while water coverage might function as a diffusion barrier from soils or sediments to the atmosphere. The concentrations of atmospheric PH(3) (ng m(-3)) above different wetlands decrease in the order of paddy fields (51.8 ± 3.1) > marsh (46.5 ± 20.5) > lake (37.0 ± 22.7) > coastal wetland (1.71 ± 0.73). Highest atmospheric PH(3) levels in marsh are found in summer. In paddy fields, atmospheric PH(3) concentrations in flourishing stages are higher than those in slowly growing stages.

Phosphine migration at the water-air interface in Lake Taihu, China

The diurnal atmospheric phosphine (PH3) concentrations and fluxes at the water-air interface in Lake Taihu were reported. The results showed that the PH3 flux at the water-air interface ranged from -69.9±29.7 to 121±42 ng m(-2) h(-1), with a mean flux of 14.4±22.5 ng m(-2) h(-1). The fluxes were both negative and positive during the diurnal period, indicating that the lake can act as a sink and a source of PH3. In addition, the PH3 fluxes were positively correlated with water temperature, total soluble phosphorus and soluble reactive phosphorus, while they were negatively correlated with water redox potential. A similar diurnal variation curve of atmospheric PH3 concentrations was observed during all four seasons, with the maximum level occurring in early morning and the minimum appearing around midday. These findings suggest that light plays an important role in the elimination of atmospheric PH3. A significant positive correlation was also found between air temperature and atmospheric PH3 concentration. The mean flux of PH3 in Lake Taihu was higher than in other reported wetlands, with an estimated annual emission of PH3 to the atmosphere of 2.94×10(5) g y(-1).

Determination of phosphine and other fumigants in air samples by thermal desorption and 2D heart-cutting gas chromatography with synchronous SIM/Scan mass spectrometry and flame photometric detection

Fumigants and volatile industrial chemicals are particularly hazardous to health when a freight container is fumigated or the contaminated material is introduced into its enclosed environment. Phosphine is now increasingly used as a fumigant, after bromomethane--the former fumigant of choice--has been banned by the Montreal Protocol. We have enhanced our previously established thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method by integrating a second gas chromatographic dimension and a flame photometric detector to allow the simultaneous detection of phosphine and volatile organic compounds (VOCs), providing a novel application. A thermal desorption system is coupled to a two dimensional gas chromatograph using both mass spectrometric and flame photometric detection (TD-2D-GC-MS/FPD). Additionally, the collection of mass spectrometric SIM and Scan data has been synchronised, so only a single analysis is now sufficient for qualitative scanning of the whole sample and for sensitive quantification. Though detection limits for the herewith described method are slightly higher than in the previous method, they are in the low μL m(-3) range, which is not only below the respective occupational exposure and intervention limits but also allows the detection of residual contamination after ventilation. The method was developed for the separation and identification of 44 volatile substances. For 12 of these compounds (bromomethane, iodomethane, dichloromethane, 1,2-dichlorethane, benzene, tetrachloromethane, 1,2-dichloropropane, toluene, trichloronitromethane, ethyl benzene, phosphine, carbon disulfide) the method was validated as we chose the target compounds due to their relevance in freight container handling.

Phosphorus fractions and matrix-bound phosphine in coastal surface sediments of the Southwest Yellow Sea

This paper characterizes the distribution of phosphorus fractions and matrix-bound phosphine (MBP) in coastal surface sediments of the Southwest Yellow Sea from 2006 to 2007. Total phosphorus (TP), inorganic phosphorus (IP) and organic phosphorus (OP) concentrations (mg kg(-1)) range from 278 +/- 3 to 768 +/- 15, 160 +/- 1 to 653 +/- 27, and 3.42+/- 0.05 to 267 +/- 22, respectively. MBP is a small portion of TP with values of 0.69 +/- 0.06 to 179 +/- 29 ng kg(-1). Phosphorus fractions and MBP are influenced strongly by riverine input and hydrodynamic conditions. High TP and MBP are found in the old Yellow River mouth and the Yangtze River mouth. OP and MBP are strongly negatively correlated to mean particle size. Significant positive correlations are found between MBP and IP and OM, suggesting that MBP production may be the microbially intermediated transformation of IP.

Production and emission of phosphine gas from wetland ecosystems

Phosphine is a part of an atmospheric link of phosphorus cycle on earth, which could be an important pathway for phosphorus transport in environment. Wetland ecosystems are important locations for global biogeochemical phosphorus cycle. In this study, production and emission fluxes of free phosphine from four wetlands types in southern China were observed in different seasons. The results showed that the concentration of phosphine liberated from wetlands was at pg/m3-ng/m3 level. The emission concentrations of different wetlands followed the sequence: paddy field (51.83 +/- 3.06) ng/m3 > or = marsh (46.54 +/- 20.55) ng/m3 > lake (37.05 +/- 22.74) ng/m3 >> coastal wetland (1.71 +/- 0.73) ng/m3, the positive phosphine emission flux occurred in rice paddy field (6.67 +/- 5.18) ng/(m2 x hr) and marsh (6.23 +/- 26.9) ng/(m2 x hr), while a negative phosphine flux of (-13.11 +/- 35.04) ng/(m2 x hr) was observed on the water-air interface of Lake Taihu, suggesting that paddy field and marsh may be important sources for phosphine gas in atmosphere, while lake may be a sink of atmospheric phosphine gas during the sampling period. Atmospheric phosphine levels and emission flux from Yancheng marsh and rice paddy field varied in different seasons and vegetational zones. Both diffusion resistance in aqueous phase and temperature were dominating factors for the production and transportation of phosphine to atmosphere.

[Effects of free-air CO2 enrichment on phosphine emission from rice field]

Phosphine, a trace gas, has been proved to commonly exist in environment. Under free air carbon dioxide enrichment (FACE) condition, the phosphine fluxes were investigated on the function of different nitrogen fertilizer application, NN (normal N, 250 kg/hm2) and LN (low N, 125 kg/hm2). Results showed that phosphine fluxes and concentrations in flourishing stages, both tillering stage and elongation stage, were higher than in slowly growing stages. The highest phosphine flux of (155.2 +/- 22.71) ng/(m2 x h) was observed in tillering stage in NN zone of the FACE area. The highest average phosphine flux of (41.72 +/- 7.006) ng/(m2 x h) was observed in NN zone of FACE area, while the lowest average phosphine flux of (- 1.485 +/- 6.229) ng/(m2 x h) could be detected in LN zone of the ambient area. CO2 enrichment can obviously improve the phospine emission. The nitrogen fertilizing level doesn't play an important role in phosphine emission. Both net fluxes and concentrations of phosphine had obviously positive correlation with temperature. A one-day phosphine flux and concentration experiment was carried out in ripening stage. The result showed that light was the prominent factor influencing phosphine concentration in daytime.

Occurrence of matrix-bound phosphine in intertidal sediments of the Yangtze Estuary

This study investigated the levels and potential transformation of matrix-bound phosphine in the intertidal sediments (0-5cm) of the Yangtze Estuary. Matrix-bound phosphine concentrations in sediments ranged from 0.65 to 3.25ngkg(-1), with an annual average of 1.53ngkg(-1). In freshwater sediments, the concentrations of matrix-bound phosphine were significantly higher than in the brackish sediments. The maximum concentrations of matrix-bound phosphine appeared in July (1.17-3.25ngkg(-1)), followed by May (0.92-3.01ngkg(-1)), November (0.65-2.41ngkg(-1)) and January (0.51-1.42ngkg(-1)). Matrix-bound phosphine derived probably from the mechanochemical reduction of apatite-bound phosphate and the microbial conversion of organic phosphorus in the intertidal sediments. Its spatial and seasonal distributions, however, were regulated by salinity and sediment temperature. Compared with other aquatic systems (e.g. rivers, lakes and coastal seas), a low level of matrix-bound phosphine was observed in the intertidal sediments, probably implicating a relatively rapid turnover of phosphine in the system.

Conformational analysis and stereochemical dependences of (31)P-(1)H spin-spin coupling constants of bis(2-phenethyl)vinylphosphine and related phosphine chalcogenides

Theoretical energy-based conformational analysis of bis(2-phenethyl)vinylphosphine and related phosphine oxide, sulfide and selenide synthesized from available secondary phosphine chalcogenides and vinyl sulfoxides is performed at the MP2/6-311G** level to study stereochemical behavior of their (31)P-(1)H spin-spin coupling constants measured experimentally and calculated at different levels of theory. All four title compounds are shown to exist in the equilibrium mixture of two conformers: major planar s-cis and minor orthogonal ones, while (31)P-(1) H spin-spin coupling constants under study are found to demonstrate marked stereochemical dependences with respect to the geometry of the coupling pathways, and to the internal rotation of the vinyl group around the P(X)-C bonds (X = LP, O, S and Se), opening a new guide in the conformational studies of unsaturated phosphines and phosphine chalcogenides.

Stimulation of gaseous phosphine production from Antarctic seabird guanos and ornithogenic soils

Matrix-bound phosphine (MBP) is a general term used to indicate non-gaseous reduced phosphorus compounds that are transformed into phosphine gas upon reaction with bases or acids. Antarctic seabird guanos and ornithogenic soils were used as materials to compare the different digestion methods for transforming matrix-bound phosphine into phosphine gas. The results demonstrated that more phosphine gas in most of Antarctic environmental materials was formed of matrix-bound phosphine by caustic digestion than by acidic digestion. The comparative study on different digestion methods also revealed that the fraction of MBP converted to gaseous phosphine during the digestion depended on the temperature. The optimal digestion temperature was close to 70 degrees C and the optimal digestion time was about 20 min. Acidic conditions were more favorable for the release of matrix-bound phosphine compared to the neutral conditions. A proper water dilution can increase the production and emission of phosphine from the Antarctic penguin guanos.

Seasonal and spatial distribution of matrix-bound phosphine and its relationship with the environment in the Changjiang River Estuary, China

Sediment is commonly considered as a source of phosphine, which is a highly toxic and reactive atmospheric trace gas. This study aims to investigate the seasonal and spatial distribution of matrix-bound phosphine (MBP) and its relationship with the environment in the Changjiang River Estuary. A total of 43 surface sediments were collected in four seasons of 2006, and concentrations of MBP and relative environmental factors were analyzed. MBP ranged from 1.93 to 94.86ng kg(-1) dry weight (dw) with an average concentration of 17.14ng kg(-1)dw. The concentrations of MBP in the upper estuary were higher than those in the lower estuary, which could be attributed to greater pollutant inputs in the upper estuary. The concentrations of MBP also varied with season, with November > August > May > February. Significant correlations existed between MBP and total phosphorus (TP), organic phosphorus (OP), inorganic phosphorus (IP), organic carbon (OC), total nitrogen (TN), the grain size, and redox potential (Eh), suggesting that these sedimentary environmental characteristics played an important role in controlling the MBP levels in the sediments. Notably, there were positive linear relationships between the concentrations of soluble reactive phosphorus (SRP), TP, and chlorophyll a (Chl a) in bottom water and MBP in sediments. These relationships might be very complicated and need further exploration. This work is the first comprehensive study of the seasonal and spatial distribution of MBP in sediments and its relationships with environmental factors in a typical estuary, and will lead to deeper understanding of the phosphorus (P) biogeochemical cycle.

Distribution characteristics of matrix-bound phosphine along the coast of China and possible environmental controls

Matrix-bound phosphine (MBP) concentrations in surface sediments collected from 37 stations along the coast of China in 2006 are reported. MBP was found in all samples and the average concentration was 6.30ngkg(-1)dry weight (dw). The distribution of MBP showed certain spatial variation characteristics with high MBP concentrations at stations near to the coast. The average concentrations of MBP in the northern Yellow Sea (NYS), the southern Yellow Sea (SYS), the northern area of East China Sea (NECS), the southern area of East China Sea (SECS), and South China Sea (SCS) were 5.57+/-3.78, 3.78+/-2.81, 5.27+/-3.07, 5.48+/-4.05 and 13.52+/-7.86ngkg(-1)dw, respectively. The correlations between MBP and influencing factors, such as the sedimentary environmental characteristics (sediment type, the grain size, contents of phosphorous, organic matters and redox potential) and the aquatic environmental characteristics (temperature, salinity, depth and hydrodynamics) were studied. The results indicated that MBP was strongly influenced by various factors, such as total phosphorus (TP), organic phosphorus (OP), organic carbon (OC), the grain size and hydrodynamics, all of which not only offered reasonable interpretations for the distribution characteristics of MBP but also provided evidence to support the viewpoint that phosphine originated from OP decomposition. This work is the first comprehensive study of the distribution of MBP along the coast of China and its relationships with environmental factors which will lead to a better understanding of the phosphorus (P) biogeochemical cycle in the sea.

Tandem mass spectrometry and hydrogen/deuterium exchange studies of protonated species of 1,1'-bis(diphenylphosphino)-ferrocene oxidative impurity generated during a Heck reaction

Oxidation of 1,1'-bis(diphenylphosphino)-ferrocene (DPPF) was found to occur when it served as the ligand for Pd(II)(CH3COO)2 in a Heck reaction. This oxidative impurity of DPPF, referred to as DPPF(O), was identified by high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) and exact mass measurements. Protonated DPPF(O) exhibited unique fragmentation pathways in the gas phase. Hydrogen/deuterium (H/D) exchange experiments provided important insights into the dissociation mechanisms of protonated DPPF(O), suggesting the existence of isomeric structures of the product ions by retaining or losing a proton (or deuteron) upon collision-induced dissociation (CID). The specific fate of the proton (or deuteron) upon CID is postulated to be dependent on the distance between the exchangeable proton (or deuteron) and the sites of bond cleavage. Density functional theory (DFT) calculations at the B3LYP/LANL2DZ level of theory showed that oxygen in DPPF(O) plays a pivotal role in invoking pi-cation interactions between the p-type lone pair electrons (n pi) in oxygen and the anti-bonding orbital of Fe(II), accounting for the major fragmentation pathways of protonated DPPF(O). Facile formation of organometallic distonic ions in dissociation of protonated DPPF(O), and especially of protonated DPPF, could be useful for further exploration of their chemical properties by gas-phase ion/molecule reactions.

Capillary-based, serial-loading, parallel microreactor for catalyst screening

Soluble metal-ligand complexes are useful as catalysts for many organic reactions. The large number of metals and ligands available suggests a combinatorial approach to catalyst discovery. Carrying out reactions in very small (microliter) volumes in capillaries has many advantages in this regard, including material conservation, isolation from the atmosphere, and ease of transport of species by using pressure-induced flow. We have developed a capillary reactor in which separate zones of catalyst and reactants are combined and react. Zones are loaded serially into the capillary reactor from an autosampler, they react in parallel in the capillary reactor (at elevated temperature) and are ejected serially and under computer control for analysis by online GC. Offline analysis following sample collection is also possible. The Stille cross-coupling reaction has been the focus of our recent activity. Known palladium-based precatalysts and phosphine or arsine ligands were screened to validate the approach taken here. The results largely agree with results obtained by traditional organic synthesis, validating the method. The throughput of the nonoptimized system is over two 5-h reactions/h. For example, 40 5-h reactions examining the effect of catalyst loading were performed in 2 9-h runs requiring a total of 2 h of operator time.

Phosphine containing oligonucleotides for the development of metallodeoxyribozymes

Novel transition metal catalysts based on oligonucleotides can be easily obtained by functionalization of 5-iodouridine with phosphine ligands, resulting in good asymmetric induction in palladium catalyzed allylic nucleophilic substitution.

Evaluation of microwave irradiation for analysis of carbonyl sulfide, carbon disulfide, cyanogen, ethyl formate, methyl bromide, sulfuryl fluoride, propylene oxide, and phosphine in hay

Fumigant residues in hay were "extracted" by microwave irradiation. Hay, in gastight glass flasks, was placed in a domestic microwave oven, and fumigants were released into the headspace by microwave irradiation. Power settings for maximum release of fumigants were determined for carbonyl sulfide (COS), carbon disulfide (CS(2)), cyanogen (C(2)N(2)), ethyl formate (EF), methyl bromide (CH(3)Br), sulfuryl fluoride (SF), propylene oxide (PPO), and phosphine (PH(3)). Recoveries of fortified samples were >91% for COS, CS(2), CH(3)Br, SF, PPO, and PH(3) and >76% for C(2)N(2) and EF. Completeness of extraction was assessed from the amount of fumigant retained by the microwaved hay. This amount was determined from further microwave irradiation and was always small (<5% of the amount obtained from the initial procedure). Limits of quantification were <0.1 mg/kg for COS, CS(2), C(2)N(2), EF, and PH(3) and <0.5 mg/kg for CH(3)Br, SF, and PPO. These low limits were essentially due to the absence of interference from solvents and no necessity to inject large-volume gas samples. The microwave method is rapid and solvent-free. However, care is required in selecting the appropriate power setting. The safety implications of heating sealed flasks in microwave ovens should be noted.