Total mercury determination in different tissues of broiler chicken by using cloud point extraction and cold vapor atomic absorption spectrometry

Rapid and Portable Detection of Hg and Cd in Grain Samples Based on Novel Catalytic Pyrolysis Composite Trap Coupled with Miniature Atomic Absorption Spectrometry

As toxic metals, Hg and Cd are a concern for food safety and human health; their rapid and portable analysis is still a challenge. A portable and rapid Hg-Cd analyzer constructed from a metal-ceramic heater (MCH)-based electrothermal vaporizer (ETV), an on-line catalytic pyrolysis furnace (CPF), a composite Pt/Ni trap, and a homemade miniature atomic absorption spectrometer (AAS) was proposed for grain analysis in this work. To enhance sensitivity, a new folded light path was designed for simultaneous Hg and Cd analysis using charge coupled device (CCD) in AAS. To eliminate the grain matrix interference, a catalytic pyrolysis furnace with aluminum oxide fillers was utilized to couple with a composite Pt/Ni trap. The method limits of detection (LODs) were 1.1 μg/kg and 0.3 μg/kg for Hg and Cd using a 20 mg grain sample, fulfilling the real sample analysis to monitor the grain contamination quickly; linearity R² > 0.995 was reached only using standard solution calibration, indicating the sample was free of grain matrix interference. The favorable analytical accuracy and precision were validated by analyzing real and certified reference material (CRM) grains with recoveries of 97-103% and 96-111% for Hg and Cd, respectively. The total analysis time was less than 5 min without sample digestion or use of any chemicals, and the instrumental size and power consumption were <14 kg and 270 W, respectively. Compared with other rapid methods, this newly designed Hg-Cd analyzer is proven to be simple, portable, and robust and is, thus, suitable to quickly monitor Hg and Cd contamination in the field to protect grain and food safety.

The Distribution of Selected Toxic Elements in Sauced Chicken during Their Feeding, Processing, and Storage Stages

Sauced chicken is popular food worldwide. However, the elemental pollution of poultry industrialization has led to an increasing health risk concern. In this study, four typical toxic elements, including chromium (Cr), arsenic (As), lead (Pb), and cadmium (Cd), were selected and detected in whole industry chains of sauced chicken preparation by inductively coupled plasma-mass spectrometry. The detection method was optimized and verified with an average recovery of 93.96% to 107.0%. Cr has the highest proportion among the elements during the three stages, while the content of Cd was the least. In the feeding stages, elements were at the highest level in the starter broiler, and the grower broiler was considered to have a good metabolic capacity of them. In addition, the elements were mainly distributed in the chicken kidney, gizzard, liver, leg, wing, and lung. In the processing stage, the elements continued to accumulate from the scalding to the sterilization process. The elements were mainly distributed in the chicken wing, leg, head, and breast. In the storage stage, the elements almost kept constant in the polyamide and polyethylene packaging, while it showed irregular small-range fluctuations in the other two packages. This study provides beneficial references for the toxic element risk management in the whole industry chain.

A scoping review of sources of mercury and its health effects among Pakistan's most vulnerable population

Mercury and methyl mercury are poisonous to human body. In the recent times, exposure to mercury has been anthropogenic in nature. Within the past several decades, many incidences of mercury poisoning have been documented in several countries including Pakistan. Mercury has been ingested where it has been used to preserve crops, through the point and non-point source discharge into the surface water, and consequently entering the food chain. We conducted this scoping review of mercury and its health effects in Pakistan in order to raise the flag to a silent ongoing Minamata disease in the country. We conducted a systematic search of the available literature in Google Scholar, PubMed, and grey literature of unpublished theses and reports of various universities across the country. We found that in the northern Pakistan, suspended sediments were the major pathway of the riverine mercury transport. Sediments of Hunza and Gilgit River were found high in mercury concentrations. Gold mining leads to an increase in mercury concentration in soil and river waters flowing in this region. High concentrations up to 108 ng/L were found in Shimsal River. It is suspected that that high level of mercury transport may be leading to accumulation of mercury in major water bodies and lakes downstream. Occupational exposure to mercury and other heavy metals is common in an unregulated private sector of the country. Goldsmiths burn the amalgamated gold without personal protective measures. Direct exposure to the fumes of mercury leads to respiratory, dermatological, systemic and neurological ailments specific to mercury poisoning. We found good evidence of bioaccumulation of mercury in fish and fish products in Pakistan. The untreated waste water discharge is responsible to not only afflicted the fish but also the birds which feed on this fish. Further, the same untreated waste water from factories and agriculture runoffs affect vegetables grown in it. Studies looking at the biomarkers for mercury in humans have shown increased and even toxic levels of mercury among the most vulnerable populations of the country. Other sources of mercury exposure included mercury in traditional medicines and cigarette products. Though no evidence was found for its presence in drinking water, its existence in the food chain and occupational exposure pose great threat to the humans as well as animals.

Interference-free, green microanalytical method for total mercury and methylmercury determination in biological and environmental samples using small-sized electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry

An analytical method for the quantification of total Hg and CH₃Hg⁺ in biological tissues (fish, mushroom) and water sediment was developed based on small-sized electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry using a low-resolution microspectrometer as detector. Sample preparation was carried out according to the procedure recommended by JRC Technical Report of European Commission for the determination of CH₃Hg⁺ in seafood and adapted by us for lower consumption of reagents. Amounts of 0.1 - 0.5 g sample were subjected to extraction in 5 ml of 47% HBr then CH₃Hg⁺ was extracted in 2 × 1 ml toluene and back-extracted in 2 ml aqueous solution of 1% l-cysteine. Total Hg/CH₃Hg⁺ were quantified in 10 μl of acidic extract/l-cysteine solution after electrothermal vaporization and measurement of 253.652 nm Hg signal in the episodic emission spectra. Under the optimal working conditions of system (70 °C sample drying, 1300 °C sample vaporization, 10 W plasma power and 150 ml min^-1 Ar flow) the limits of detection were 7.0 μg kg^-1 total Hg and 3.5 μg kg^-1 CH₃Hg⁺. Comparison of slopes in external calibration and standard addition procedure revealed the lack of non-spectral interferences of multimineral matrix, so that the calibration against Hg²⁺ standards was adopted. Pooled recovery of total mercury/methylmercury was 101 ± 7%/100 ± 7%, while precision assessed from measurements of real samples was in the range 1.6-9.6%/2.7-12.8%. The proposed method validated according to Eurachem Guide 2014 is selective and complies with demands in European legislation (Decisions 657/2002; 333/2007; 836/2011) and Association of Official Analytical Chemists Guide in terms of performances for food control. The method displays a high degree of greenness by circumventing cold vapor generation, use of small amounts of reagents and full-miniaturized instrumentation resulting in low analytical costs without reducing results quality. Besides, the method is simple and rapid, since it uses external calibration curves prepared from Hg²⁺standard solutions both for total Hg and CH₃Hg⁺ determination.

Use of 2-Hydrazinobenzothiazole-Modified Copolymer(s) as Potential Chelating Agent for Sensitive and Selective Determination of Low Levels of Mercury in Seafood by Ultrasound-Assisted Cloud-Point Extraction Combined with Spectrophotometry

In this study, a new method was developed for the pre-concentration of trace mercury from seafood samples prior to analysis by spectrophotometry. The method is based on the complexation between 2-hydrazinobenzothiazole (2-HBT)-modified copolymer(s) and Hg(II) in the presence of an ionic surfactant, cetyltrimethylammonium bromide (CTAB), as sensitivity enhancer at pH 4.5 and the extraction of the complex into the surfactant-rich phase of polyethylene glycol tert-octylphenyl ether (Triton X-114) as the extractant. The variables affecting extraction efficiency were evaluated and optimized. Due to the observation that the modified copolymers are 2.5-fold more sensitive and selective to the Hg²⁺ ions than the CH₃Hg⁺, the amounts of free Hg²⁺ and total Hg were determined at 325 nm by spectrophotometric detection of free Hg²⁺ and total Hg in the pre-treated and extracted fish samples using dilute acid mixture containing Triton X-114 and K₂Cr₂O₇, before and after oxidation of CH₃Hg⁺ to Hg²⁺ with mixture of KBr and KBrO₃ in the acidic media. The amount of CH₃Hg⁺ was calculated from the difference between total Hg and free Hg²⁺ amounts. The accuracy was tested by analysis of two certified samples. The results were statistically in good agreement with the certified values, and the precision was lower than 6.4%. The limits of detection were 1.40 (1.58) and 1.91 (2.11) μg L^-1 for Hg²⁺ from the two calibration solutions spiked before the pre-treatment, respectively. It has been observed that there is no significant matrix effect by comparison of slopes of the calibration curves. The method was applied to seafood samples for speciation analysis of free Hg²⁺ and CH₃Hg⁺. In terms of speciation, while total Hg is detected in the range of 12.6-143.8 μg kg^-1, the distribution of mercury in seafood was in the range of 7.4-53.3 μg kg^-1 for CH₃Hg⁺ and in 8.3-90.5 μg kg^-1 for free Hg²⁺.

Vitamin E succinate-grafted-chitosan/chitosan oligosaccharide mixed micelles loaded with C-DMSA for Hg2+ detection and detoxification in rat liver

AIM

To determine whether the use of a mixed polymeric micelle delivery system based on vitamin E succinate (VES)-grafted-chitosan oligosaccharide (CSO)/VES-grafted-chitosan (CS) mixed micelles (VES-g-CSO/VES-g-CS MM) enhances the delivery of C-DMSA, a theranostic fluorescent probe, for Hg2+ detection and detoxification in vitro and in vivo.

METHODS

Mixed micelles self-assembled from two polymers, VES-g-CSO and VES-g-CS, were used to load C-DMSA and afforded C-DMSA@VES-g-CSO/VES-g-CS MM for cell and in vivo applications. Fluorescence microscopy was used to assess C-DMSA cellular uptake and Hg2+ detection in L929 cells. C-DMSA@VES-g-CSO/VES-g-CS MM was then administered intravenously. Hg2+ detection was assessed by fluorescence microscopy in terms of bio-distribution while detoxification efficacy in Hg2+-poisoned rat models was evaluated in terms of mercury contents in blood and in liver.

RESULTS

The C-DMSA loaded mixed micelles, C-DMSA@VES-g-CSO/VES-g-CS MM, significantly enhanced cellular uptake and detoxification efficacy of C-DMSA in Hg2+ pretreated human L929 cells. Evidence from the reduction of liver coefficient, mercury contents in liver and blood, alanine transaminase and aspartate transaminase activities in Hg2+ poisoned SD rats treated with the mixed micelles strongly supported that the micelles were effective for Hg2+ detoxification in vivo. Furthermore, ex vivo fluorescence imaging experiments also supported enhanced Hg2+ detection in rat liver.

CONCLUSION

The mixed polymeric micelle delivery system could significantly enhance cell uptake and efficacy of a theranostic probe for Hg2+ detection and detoxification treatment in vitro and in vivo. Moreover, this nanoparticle drug delivery system could achieve targeted detection and detoxification in liver.

Utility of ultrasound assisted-cloud point extraction and spectophotometry as a preconcentration and determination tool for the sensitive quantification of mercury species in fish samples

The current study reports, for the first time, the development of a new analytical method employing ultrasound assisted-cloud point extraction (UA-CPE) for the extraction of CH₃Hg⁺ and Hg²⁺ species from fish samples. Detection and quantification of mercury species were performed at 550nm by spectrophotometry. The analytical variables affecting complex formation and extraction efficiency were extensively evaluated and optimized by univariate method. Due to behave 14-fold more sensitive and selective of thiophene 2,5-dicarboxylic acid (H₂TDC) to Hg²⁺ ions than CH₃Hg⁺ in presence of mixed surfactant, Tween 20 and SDS at pH5.0, the amounts of free Hg²⁺ and total Hg were spectrophotometrically established at 550nm by monitoring Hg²⁺ in the pretreated- and extracted-fish samples in ultrasonic bath to speed up extraction using diluted acid mixture (1:1:1, v/v, 4molL^-1 HNO₃, 4molL^-1 HCl, and 0.5molL^-1 H₂O₂), before and after pre-oxidation with permanganate in acidic media. The amount of CH₃Hg⁺ was calculated from difference between total Hg and Hg²⁺ amounts. The UA-CPE method showed to be suitable for the extraction and determination of mercury species in certified reference materials. The results were in a good agreement (with Student's t-test at 95% confidence limit) with the certified values, and the relative standard deviation was lower than 3.2%. The limits of detection have been 0.27 and 1.20μgL^-1, for Hg²⁺ from aqueous calibration solutions and matrix-matched calibration solutions spiked before digestion, respectively, while it is 2.43μgL^-1 for CH₃Hg⁺ from matrix-matched calibration solutions. A significant matrix effect was not observed from comparison of slopes of both calibration curves, so as to represent the sample matrix. The method was applied to fish samples for speciation analysis of Hg²⁺ and CH₃Hg⁺. In terms of speciation, while total Hg is detected in range of 2.42-32.08μgkg^-1, the distribution of mercury in fish were in range of 0.7-11.06μgkg^-1 for CH₃Hg⁺ and in range of 1.72-24.56μgkg^-1 for Hg²⁺.

Mercury risk in poultry in the Wanshan Mercury Mine, China

In this study, total mercury (THg) and methylmercury (MeHg) concentrations in muscles (leg and breast), organs (intestine, heart, stomach, liver) and blood were investigated for backyard chickens, ducks and geese of the Wanshan Mercury Mine, China. THg in poultry meat products range from 7.9 to 3917.1 ng/g, most of which exceeded the Chinese national standard limit for THg in meat (50 ng/g). Elevated MeHg concentrations (0.4-62.8 ng/g) were also observed in meat products, suggesting that poultry meat can be an important human MeHg exposure source. Ducks and geese showed higher Hg levels than chickens. For all poultry species, the highest Hg concentrations were observed in liver (THg: 23.2-3917.1 ng/g; MeHg: 7.1-62.8 ng/g) and blood (THg: 12.3-338.0 ng/g; MeHg: 1.4-17.6 ng/g). We estimated the Hg burdens in chickens (THg: 15.3-238.1 μg; MeHg: 2.2-15.6 μg), ducks (THg: 15.3-238.1 μg; MeHg: 3.5-14.7 μg) and geese (THg: 83.8-93.4 μg; MeHg: 15.4-29.7 μg). To not exceed the daily intake limit for THg (34.2 μg/day) and MeHg (6 μg/day), we suggested that the maximum amount (g) for chicken leg, breast, heart, stomach, intestine, liver, and blood should be 1384, 1498, 2315, 1214, 1081, 257, and 717, respectively; the maximum amount (g) for duck leg, breast, heart, stomach, intestine, liver, and blood should be 750, 1041, 986, 858, 752, 134, and 573, respectively; and the maximum amount (g) for goose leg, breast, heart, stomach, intestine, liver, and blood should be 941, 1051, 1040, 1131, 964, 137, and 562, respectively.

On the use of certified reference materials for assuring the quality of results for the determination of mercury in environmental samples

This work focused on the development and validation of methodologies for the accurate determination of mercury in environmental samples and its further application for the preparation and certification of new reference materials (RMs). Two certified RMs ERM-CC580 (inorganic matrix) and ERM-CE464 (organic matrix) were used for the evaluation of digestion conditions assuring the quantitative recovery of mercury. These conditions were then used for the digestion of new candidates for the environmental RMs: bottom sediment (M_2 BotSed), herring tissue (M_3 HerTis), cormorant tissue (M_4 CormTis), and codfish muscle (M_5 CodTis). Cold vapor atomic absorption spectrometry (CV AAS) and inductively coupled plasma mass spectrometry (ICP MS) were used for the measurement of mercury concentration in all RMs. In order to validate and assure the accuracy of results, isotope dilution mass spectrometry (IDMS) was applied as a primary method of measurement, assuring the traceability of obtained values to the SI units: the mole, the kilogram, and the second. Results obtained by IDMS using n(²⁰⁰Hg)/n(²⁰²Hg) ratio, with estimated combined uncertainty, were as follows: (916 ± 41)/[4.5 %] ng g^-1 (M_2 BotSed), (236 ± 14)/[5.9 %] ng g^-1 (M_3 HerTis), (2252 ± 54)/[2.4 %] ng g^-1 (M_4 CormTis), and (303 ± 15)/[4.9 %] ng g^-1 (M_CodTis), respectively. Different types of detection techniques and quantification (external calibration, standard addition, isotope dilution) were applied in order to improve the quality of the analytical results. The good agreement (within less than 2.5 %) between obtained results and those derived from the Inter-laboratory Comparison, executed by the Institute of Nuclear Chemistry and Technology (Warsaw, Poland) on the same sample matrices, further validated the analytical procedures developed in this study, as well as the concentration of mercury in all four new RMs. Although the developed protocol enabling the metrological certification of the reference value was exemplified by the determination of mercury in environmental samples, it could be considered as valid for any certification procedure required whenever new certified RMs are introduced.

Detoxification of mercury pollutant leached from spent fluorescent lamps using bacterial strains

The spent fluorescent lamps (SFLs) are being classified as a hazardous waste due to having mercury as one of its main components. Mercury is considered the second most toxic heavy metal (arsenic is the first) with harmful effects on animal nervous system as it causes different neurological disorders. In this research, the mercury from phosphor powder was leached, then bioremediated using bacterial strains isolated from Qatari environment. Leaching of mercury was carried out with nitric and hydrochloric acid solutions using two approaches: leaching at ambient conditions and microwave-assisted leaching. The results obtained from this research showed that microwave-assisted leaching method was significantly better in leaching mercury than the acid leaching where the mercury leaching efficiency reached 76.4%. For mercury bio-uptake, twenty bacterial strains (previously isolated and purified from petroleum oil contaminated soils) were sub-cultured on Luria Bertani (LB) plates with mercury chloride to check the bacterial tolerance to mercury. Seven of these twenty strains showed a degree of tolerance to mercury. The bio-uptake capacities of the promising strains were investigated using the mercury leached from the fluorescent lamps. Three of the strains (Enterobacter helveticus, Citrobacter amalonaticus, and Cronobacter muytjensii) showed bio-uptake efficiency ranged from 28.8% to 63.6%.

Complex-forming organic ligands in cloud-point extraction of metal ions: a review

Cloud-point extraction (CPE), an easy, safe, environmentally friendly, rapid and inexpensive methodology for preconcentration and separation of trace metals from aqueous solutions has recently become an attractive area of research and an alternative to liquid-liquid extraction. Moreover, it provides results comparable to those obtained with other separation techniques and has a greater potential to be explored in improving detection limits and other analytical characteristics over other methods. A few reviews have been published covering different aspects of the CPE procedure and its relevant applications, such as the phenomenon of clouding, the application in the extraction of trace inorganic and organic materials, as well as pesticides and protein substrates from different sources, or incorporation of CPE into an FIA system. This review focuses on general properties of the most frequently used organic ligands in cloud-point extraction and on literature data (from 2000 to 2012) concerning the use of modern techniques in determination of metal ions' content in various materials. The article is divided according to the class of organic ligands to be used in CPE.

Hazardous impact of organic arsenical compounds in chicken feed on different tissues of broiler chicken and manure

The purpose of this study was to evaluate the translocation of arsenic (As) from feed to different tissues of broiler chicken (leg, breast, liver and heart) and excretory product (manure). The feed, broiler chicken and manure samples were collected from five selected poultry farms. The As concentrations in all samples were determined by electrothermal atomic absorption spectrometry, after microwave assisted acid digestion in closed vessels. The concentrations of As in different chicken feeds were found in the range of 21.3-43.7 μg g⁻¹. The contents of As in different tissues of broiler chicken, liver, muscles and heart were found in the range of 3.07-7.17, 2.15-5.28 and 2.11-6.36 μg g⁻¹, respectively, while manure samples contains 22.8-50.3 μg g⁻¹. The obtained data shows the high correlation coefficient between As contents in feed, excretory product or manure and tissues of broiler chicken in the range of r=0.41-0.83. The high level of As in excretory product may add toxicant to environment, on their disposal.

Simultaneous preconcentration of copper and mercury in water samples by cloud point extraction and their determination by inductively coupled plasma atomic emission spectrometry

A cloud-point extraction process coupled to ICP-OES by using 3-nitro benzaldehyde thiosemicarbazone (3-NBT) as complexing agent was developed for the simultaneous preconcentration and determination of copper and mercury in water samples. The variables affecting the complexation and extraction steps were optimized. Under the optimum conditions (i.e. 1.5×10(-5) mol L(-1) ligand, 0.3% (v/v) Triton X-114, 55 °C equilibrium temperature, incubation time of 30 min) the calibration graphs were linear in the range of 5-120 and 10-100 ng mL(-1) with enhancement factor of 82.7 and 51.3 for Cu(2+) and Hg(2+), respectively. The preconcentration factors were 28.6 in both cases and detection limits were obtained 0.48 for Cu and 1.1 ng mL(-1) for Hg. The precisions (R.S.D.%) for five replicate determinations at 50 ng mL(-1) of copper and mercury were better than 1.8% and 3.2%, respectively. The accuracy of the proposed method is validated by analyzing a certified reference material of water (RTC-QCI-049) with satisfactory results. Finally, the proposed method was utilized successfully for the determination of copper and mercury in surface water (river), tap water and bottled mineral water samples.

Automatic flow-batch system for cold vapor atomic absorption spectroscopy determination of mercury in honey from Argentina using online sample treatment

An automatic flow-batch system that includes two borosilicate glass chambers to perform sample digestion and cold vapor atomic absorption spectroscopy determination of mercury in honey samples was designed. The sample digestion was performed by using a low-cost halogen lamp to obtain the optimum temperature. Optimization of the digestion procedure was done using a Box-Behnken experimental design. A linear response was observed from 2.30 to 11.20 μg Hg L(-1). The relative standard deviation was 3.20% (n = 11, 6.81 μg Hg L(-1)), the sample throughput was 4 sample h(-1), and the detection limit was 0.68 μg Hg L(-1). The obtained results with the flow-batch method are in good agreement with those obtained with the reference method. The flow-batch system is simple, allows the use of both chambers simultaneously, is seen as a promising methodology for achieving green chemistry goals, and is a good proposal to improving the quality control of honey.

Highly sensitive and specific determination of mercury(II) ion in water, food and cosmetic samples with an ELISA based on a novel monoclonal antibody

Mercury is one of the most toxic heavy metals present in the environment. In this study, a highly sensitive and specific monoclonal antibody (mAb)-based indirect competitive enzyme-linked immunosorbent assay (ELISA) for the determination of Hg(2+) was developed. A new bifunctional ligand, 6-mercaptonicotinic acid (MNA), which contains a pyridine ring bearing a carboxylic group and a mercapto group, was selected for the preparation of immunogen. After immunization of mice and performing the hybridoma technique, the obtained mAb was characterized for its binding affinity and selectivity for Hg(2+). Based on this novel mAb, an ELISA was established. At optimal experimental conditions, the standard curve of the ELISA for Hg(2+) was constructed in concentration range of 0.1-100 ng mL(-1). The values of IC(50) and LOD of the assay were found to be 1.12 and 0.08 ng mL(-1). The cross-reactivity was lower than 2% with MNA, CH(3)Hg, and CH(3)Hg-MNA and was 11.5% and 4.4% for Hg(+) and Au(3+), respectively. No cross-reactivity was found with other metal ions such as Cu(2+), Sn(2+), Ni(2+), Mn(2+), Pb(2+), Zn(2+), Cd(2+), Fe(2+), Co(2+), Mg(2+), Ca(2+), and anions such as Cl(-), NO(3)(-), NO(2)(-), HCO(3)(-), F(-), and SO(4)(2-), indicating that the assay displays not only high sensitivity but also high selectivity. Different kinds of samples including water, milk, green vegetable, kelp, facial cleanser, and night cream were spiked with Hg(2+) and the extracts were analyzed by ELISA. Acceptable recovery rates of 80.0-113.0% and coefficients of variation of 1.9-18.6% were obtained. A linear relationship between ELISA and cold-vapor atomic fluorescence spectroscopy (CV-AFS) as indicated by a correlation coefficient of 0.97 for liquid samples (water samples) and 0.98 for other samples was obtained. The proposed mAb-based ELISA provides a feasible analytical method for highly sensitive and specific, fast, simple, and accurate determination of uncomplexed trace Hg(2+) in environmental and food samples.

Mercury determination in non- and biodegradable materials by cold vapor capacitively coupled plasma microtorch atomic emission spectrometry

A new analytical system consisting of a low power capacitively coupled plasma microtorch (20 W, 13.56 MHz, 150 ml min(-1) Ar) and a microspectrometer was investigated for the Hg determination in non- and biodegradable materials by cold-vapor generation, using SnCl(2) reductant, and atomic emission spectrometry. The investigated miniaturized system was used for Hg determination in recyclable plastics from electronic equipments and biodegradable materials (shopping bags of 98% biodegradable polyethylene and corn starch) with the advantages of easy operation and low analysis costs. Samples were mineralized in HNO(3)-H(2)SO(4) mixture in a high-pressure microwave system. The detection limits of 0.05 ng ml(-1) or 0.08 μg g(-1) in solid sample were compared with those reported for other analytical systems. The method precision was 1.5-9.4% for Hg levels of 1.37-13.9 mg kg(-1), while recovery in two polyethylene certified reference materials in the range 98.7 ± 4.5% (95% confidence level).

Fabrication of Mercury Ion Selective Electrode Based on a Porphyrin Derivative with Plasticized PVC Membrane

An electrochemical sensing device with a plasticized polyvinyl chloride (PVC) membrane electrode based on a porphyrin derivative of p-amino tetraphenyl porphyrin (p-NH2TPP) for mercury ion (Hg2+) has been fabricated. The p-NH2TPP based PVC membrane electrode exhibited a nice linear potential performance for responding to Hg2+ in the range of 1.0×10-8 ~ 1.0×10-3 mol/L with a slope of 27.54 mV/-pC (25°C) in citrate buffer solution (pH=2.5). The detection limit was evaluated to be 7.5×10-9 mol/L. No obvious interferences were observed from Na+, K+, Ba2+, Mg2+, Ca2+, and Cr3+. The electrode possessed good stability and reproducibility. Comparing with atomic absorption spectroscopy (AAS), the electrode can be well applied to the determination of trace amount of Hg2+ in environmental waste water samples with a recovery rate of 94.83 ~ 104.78%. The sensing mechanism of the porphyrin derivative carrier for recognition of Hg2+has also been expounded by the formation of nice complexation effect between the lone pair electrons provided by four nitrogen atoms of the porphyrin molecule and unoccupied orbitals provided by the mercury ion.

Clouding behaviour in surfactant systems

A study on the phenomenon of clouding and the applications of cloud point technology has been thoroughly discussed. The phase behaviour of clouding and various methods adopted for the determination of cloud point of various surfactant systems have been elucidated. The systems containing anionic, cationic, nonionic surfactants as well as microemulsions have been reviewed with respect to their clouding phenomena and the effects of structural variation in the surfactant systems have been incorporated. Additives of various natures control the clouding of surfactants. Electrolytes, nonelectrolytes, organic substances as well as ionic surfactants, when present in the surfactant solutions, play a major role in the clouding phenomena. The review includes the morphological study of clouds and their applications in the extraction of trace inorganic, organic materials as well as pesticides and protein substrates from different sources.

Sorbent extraction of 4-(2-thiazolylazo) resorcinol (TAR)-metal chelates on Diaion SP-850 adsorption resin in order to preconcentration/separation

A sensitive and simple separation-enrichment technique for the determination of trace amounts of some metal ions was described. By the passage of aqueous samples including Fe(III), Cu(II), Ni(II) and Co(II) ions-4-(2-thiazolylazo) resorcinol (TAR) chelates through Diaion SP-850 column, metal chelates adsorb quantitatively and almost all matrix elements were passed through the column to drain. Quantitative recoveries for analyte ions were obtained at pH 6 at 3 ml/min flow rate of sample solution in 0.5 g Diaion SP-850 filled glass column. The investigations were also carried out on the interferences from other concomitant ions in the sorption process. After optimization, a preconcentration factor of 60 and a recovery values as % higher than 95 were achieved. The detection limit (N=10, 3 sigma) for Fe(III), Cu(II), Ni(II) and Co(II) were found as 3.6, 1.1, 2.8 and 2.3 microg l(-1), respectively. The applications to the determination of iron, copper, nickel and cobalt in real samples and the validation of the analytical methodology employing NIST SRM 1549 milk powder, NIST RM 8433 Corn Bran and BCR 144R Sewage sludge of domestic origin as certified reference materials were performed.

Mercury in cultured oysters (Crassostrea gigas Thunberg, 1793 and C. corteziensis Hertlein, 1951) from four coastal lagoons of the SE Gulf of California, Mexico

In order to determine the mercury concentrations in cultured oysters from coastal lagoons (SE Gulf of California), several individuals of Crassostrea gigas and C. corteziensis were collected and their mercury levels were measured with a cold vapor analyzer. The mean concentrations during the rainy and dry seasons, respectively, were 0.70 and 0.15 microg g(-1) in C. gigas and 0.56 and 0.18 microg g(-1) in C. corteziensis. During the rainy season, elevated mercury contents are apparently related to terrigen transport from the watershed, while during the dry season, the moderate levels are related to upwellings.

Arsenic and mercury in commercially valuable fish species from the Persian Gulf: influence of season and habitat

This study was undertaken to determine the concentrations of arsenic and mercury in edible muscle of pelagic (Scomberomorus commerson, Chirocentrus dorab, Sphyraena jello, Rachycentron conadum, Thunus tonggol), benthopelagic (Trichiurus lepturus, Caranx sem, Pampus argenteus, Parastromateus niger) and demersal (Nemipterus japonicas, Epinephelus coioides, Platycephalus indicus, Psettodes erumei, Pomadasys argenteus, Acanthopagrus latus) fish species from the Persian Gulf during summer and winter. The samples were analyzed by graphite furnace atomic absorption spectrometry (GFAAS) for arsenic and cold vapor atomic absorption spectrometry (CVAAS) for mercury after wet-ashing digestion. The results were expressed as μg/g of wet weight. The resulted range of contamination in fish species was between 0.156-0.834 μg/g for arsenic; and 0.120-0.527 μg/g for mercury. Also study revealed that seasonal variation influenced the concentration of the metals in the fish samples. The highest concentration of arsenic and mercury was found in Epinephelus coioides (1.011 μg/g) and Thunus tonggol (0.548 μg/g) in winter, respectively. Moreover, demersal fish species had the highest arsenic (0.481 μg/g) and mercury (0.312 μg/g) concentrations. Our study demonstrates that estimated daily and weekly intakes of arsenic and mercury via consumption of fish flesh were far below the PTDI and PTWI values established by FAO/WHO.