Comparison of four mass analyzers for determining carbosulfan and its metabolites in citrus by liquid chromatography/mass spectrometry

Four liquid chromatography/mass spectrometry (LC/MS) systems, equipped with single quadrupole, triple quadrupole (QqQ), quadrupole ion trap (QIT) and quadrupole time-of-flight (QqTOF) mass analyzers, were evaluated for the analysis of carbosulfan and its main transformation products. The comparison of quantitative aspects (sensitivity, precision and accuracy) was emphasized. Results showed that the triple quadrupole instrument reaches at least 20-fold higher sensitivity (LOD from 0.04 to 0.4 microg kg(-1)) compared to the single quadrupole (4-70 microg kg(-1)), the QIT (4-25 microg kg(-1)) and the QqTOF (4-23 microg kg(-1)) instruments. Recoveries were over 70% for all the analytes, except dibutylamine and 7-phenolcarbofuran. Repeatabilities (within-day) were slightly better by the single quadrupole (5-10%) and the QqQ (5-9%) than by the QIT (12-16%) and the QqTOF (9-16%). Both the QqTOF and QIT offer a linear dynamic range of two orders of magnitude whereas the single quadrupole and QqQ of, at least, three orders of magnitude. The method was applied to analyze carbosulfan field-treated orange samples, in which carbosulfan, carbofuran, 3-hydroxycarbofuran, and dibutylamine were found. As an example, the mean carbosulfan concentration was 20 +/- 0.6 microg kg(-1) measured by the QqQ, 22 +/- 1.2 microg kg(-1) by the single quadrupole, 25 +/- 2.8 microg kg(-1) by the QIT, and 20 +/- 1.8 microg kg(-1) by the QqTOF. Although the QqQ is more sensitive and precise, the mean values obtained by the four instruments are acceptable and comparable. The potential of each technique for the verification of the identity of residues detected in oranges is discussed using the concept of identification points.

[Analysis of phenmedipham in agricultural products by HPLC]

An analytical method was developed for the determination of phenmedipham (PM) in agricultural products using reversed-phase high-performance liquid chromatography with UV detection. A sample was extracted with acetonitrile, and the acetonitrile layer was separated by salting-out. The acetonitrile phase was isolated and evaporated. The extract was dissolved in diethyl ether-hexane (1 : 1), and then cleaned up on a Florisil column. The column was washed with diethyl ether-hexane (1 : 1), and PM was eluted with acetone-hexane (3 : 7), and the eluate was evaporated. The residue was dissolved in acetone-hexane (2 : 8), and the sample solution was cleaned up on SAX/PSA cartridge. The SAX/PSA cartridge was washed with acetone-hexane (2 : 8), and PM was eluted with acetone-hexane (3 : 7). If required, the eluate of the Florisil column was cleaned up with SAX/PSA and ENVI-Carb/ NH2 cartridges. The SAX/PSA cartridge was washed with acetone-hexane (2 : 8), and connected to be ENVI-Carb/NH2 cartridge. The cartridges were washed with acetone-hexane (3 : 7), and then the SAX/PSA cartridge was removed. PM was eluted with acetonitrile-toluene (3 : 1) from the ENVI-Carb/NH2 cartridge. PM in the eluate was separated isocratically on an ODS column (4.6 mm i.d. x 150 mm, 5 microm) using acetonitrile-water (6 : 4) as a mobile phase (flow-rate 1.0 mL/min, temp. 40 degrees C), with monitoring at 235 nm. The calibration curve was linear from 0.005 microg/mL to 10 microg/mL of PM. The recoveries of PM from eight kinds of agricultural products spiked at levels of 0.1 and 0.02 microg/g were 80.8-98.7%. The determination limit was 0.01 microg/g.

Analysis of pesticides in fruits by pressurized liquid extraction and liquid chromatography–ion trap–triple stage mass spectrometry

A multi-residue method using pressurized liquid extraction (PLE) and liquid chromatography-quadrupole ion trap-triple stage mass spectrometry (LC-IT-MS(3)) has been developed for determining trace levels of pesticides in fruits. The selected pesticides can be distinguished in: benzimidazoles and azoles, organophosphorus, carbamates, neonicotinoids, and acaricides. PLE has been optimized to extract these pesticide residues from oranges and peaches by studying the effect of experimental variables on PLE efficiency. Samples were extracted at high temperature and pressure (75 degrees C and 1500psi) using ethyl acetate as extraction solvent and acidic alumina as drying agent. The recoveries obtained by PLE ranged from 58% to 97% and the relative standard deviation (RSDs) from 5% to 19%. The limits of quantification (LOQs) of the compounds were from 0.025 to 0.25mgkg(-1), which are well-below the maximum residue limits (MRLs) established by the European Union (EU) and the Spanish legislations.

Simultaneous determination of carbamate and organophosphorus pesticides in fruits and vegetables by liquid chromatography–mass spectrometry

A liquid chromatography-mass spectrometry (LC-MS) method was established for the purpose of simultaneous determination of carbamate and organophosphorus (OPPs) pesticides in fruits and vegetables. Samples were extracted with acetonitrile; and then prepared by dispersive solid-phase extraction (dispersive-SPE) with primary secondary amine (PSA) as the sorbent. Four common representative samples (tomato, apple, carrot, and cabbage) were selected from the supermarket to investigate the effect of different matrices on pesticides recoveries and assay precision after spiking samples with 0.05 mg/kg. Matrix composition did not interfere significantly with the determination of the pesticides. The obtained recoveries were, with a few exceptions, in the range of 70-110% with RSDs less than 8%. It was applied to pesticide residue monitoring in vegetables and fruits from local markets.

[Determination of carbendazim and thiabendazole in tomatoes by solid-phase microextraction coupled with high performance liquid chromatography and fluorescence detection]

A novel method for the determination of carbendazim (MBC) and thiabendazole (TBZ) in tomatoes by solid-phase microextraction (SPME) coupled with high performance liquid chromatography (HPLC) and fluorescence detection was developed. The experimental conditions of SPME, including extraction fiber, extraction time, extraction temperature, desorption time, desorption solvent, desorption mode, pH value, organic solvent and ionic strength, and HPLC conditions were optimized. The SPME for MBC and TBZ was performed on a 65 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre for 50 min at room temperature with the solution being stirred at 1 100 r/min. The florescence detection was made at 315 nm with excitation wavelength at 280 nm. The method is linear for MBC and TBZ over the range assayed from 0.01 to 1.0 mg/kg tomatoes with the detection limits of 0.003 mg/kg and 0. 001 mg/kg and the correlation coefficients of 0.995 8 and 0.996 7, respectively. The average recoveries for MBC and TBZ were 83.5% and 85.6% with the relative standard deviations (RSDs) of 6.5% and 3.8%, respectively. The method is fast, simple, sensitive, solvent-free and suitable for the determination of MBC and TBZ in tomatoes.

Terrestrial avoidance behaviour tests as screening tool to assess soil contamination

To assess soil quality and risk assessment, bioassays can be useful tools to gauge the potential toxicity of contaminants focusing on their bioavailable fraction. A rapid and sublethal avoidance behaviour test was used as a screening tool with the earthworm Eisenia andrei and the isopod Porcellionides pruinosus, where organisms were exposed during 48 h to several chemicals (lindane, dimethoate and copper sulphate, for isopods and carbendazim, benomyl, dimethoate and copper sulphate for earthworms). Both species were also exposed to soils from an abandoned mine. For all bioassays a statistical approach was used to derive EC50 values. Isopods and earthworms were able to perceive the presence of toxic compounds and escaping from contaminated to clean soil. Furthermore the behaviour parameter was equally or more sensitive then other sublethal parameters (e.g. reproduction or growth), expressing the advantages of Avoidance Behaviour Tests as screening tools in ERA.

Determination of carbendazim residues in fruit juices by liquid chromatography-tandem mass spectrometry

In this paper a rapid optimized method for routine analysis of carbendazim residues in fruit juices is reported. The procedure is based on matrix solid-phase dispersion (MSPD) with diatomaceous earth and analysis of the extract by liquid chromatography-tandem mass spectrometry, with electrospray ionization (LC-ESI-MS/MS). In the method optimization, finding of the optimal pH for the extraction of carbendazim from juice was particularly critical. Significant matrix effects were observed, but could be eliminated using matrix-matched standards. High recoveries (82-102%), good repeatability (RSD<or=12%) and low limits of detection (0.03 ng ml-1) and quantification (0.1 ng ml-1) were achieved with this method.

[Study on fluorescence analysis for carbamate pesticides]

In the present paper the basic theory that an organic substance can emit fluorescence as it is excited by ultraviolet rays is described and the relationships between the molecular structures of organic substances and fluorescence generation are studied. According to this theory, the molecular structures of a few common carbamate pesticides such as carbaryl, carbofuran and propoxur etc.are analyzed, their fluorescence characteristics are shown, and the mechanism of fluorescence generation of carbamate pesticides is ascertained. It provides a theoretic basis for further detecting carbamate pesticides by means of a fluorescence analytical method. Moreover a steady-state fluorescence spectrograph is applied to conduct fluorescence spectrum experiments with standard carbaryl solution and carbofuran solution. The results indicate that carbamate pesticides may emit fluorescence as excited by UV under the condition of a certain solvent, and that their fluorescence spectra are distinct and have fine resolution and less interference. It is feasible to detect carbamate pesticides by fluorescence spectral analysis.

Structure determination and characterization of carbendazim hydrochloride dihydrate

The objective of this study was to synthesize and characterize the hydrochloride salt of carbendazim with the aim of improving the intrinsic solubility of the parent compound. Carbendazim hydrochloride dihydrate was synthesized for the purpose of increasing the aqueous solubility of the parent drug, carbendazim. This was done with the commonly used saturation and cooling method. The structure was determined by single crystal radiograph crystallography, and the hydrochloride salt was found to be a dihydrate. The salt crystallized in a P 2(1) 2(1) 2(1) (#19) space group, which is typical for nonplanar, achiral, and noncentrosymmetric molecules. The asymmetric unit is comprised of 1 molecule each of carbendazim and chloride and 2 water molecules. The carbendazim molecules arrange themselves in a helical structure, with the waters and the chloride molecules in the channel linking the helix. The crystal lattice is held together by numerous hydrogen bonds, as well as van der Waals interactions. The melting point of the salt is 125.6 degrees C. The solubility of the salt is 6.08 mg/mL, which is a thousand-fold increase from the intrinsic solubility (6.11 microg/mL) of the free base.

Semi disposable reactor biosensors for detecting carbamate pesticides in water

Two flow-injection biosensor systems using semi disposable enzyme reactor have been developed to determine carbamate pesticides in water samples. Acetylcholinesterase was immobilized on silica gel by covalent binding. pH and conductivity electrodes were used to detect the ionic change of the sample solution due to hydrolysis of acetylcholine. Carbamate pesticides inhibited acetylcholinesterase and the decrease in the enzyme activity was used to determine these pesticides. Parameters influencing the performance of the systems were optimized to be used in the inhibition procedure. Carbofuran and carbaryl were used to test these systems. Detection limits for the potentiometric and conductimetric systems were both at 10% inhibition corresponding to 0.02 and 0.3 ppm of carbofuran and carbaryl, respectively. Both systems also provided the same linear ranges, 0.02-8.0 ppm for carbofuran, and 0.3-10 ppm for carbaryl. The analysis of pesticides was done a few times before the reactor was disposed. Percentages of inhibition obtained from different reactors were reproducible, therefore, no recalibration was necessary when changing the reactor. The biosensors were used to analyze carbaryl in water samples from six wells in a vegetable growing area. Both systems could detect the presence of carbaryl in the samples and provided good recoveries of the added carbaryl, i.e., 80-106% for the potentiometric system and 75-105% for the conductimetric system. The presence of carbaryl in water samples analyzed by the biosensors was confirmed by gas chromatography-mass spectrometric system. These biosensors do not require any sample preconcentration and are suitable for detecting pesticides in real water samples.

Determination of carbamates and organophosphorus pesticides by SDME–GC in natural water

Water contamination due to the wide variety of pesticides used in agriculture practices is a global environmental pollution problem. Analytical methods with low quantification limits are necessary. The application of a new extraction technique, solvent drop microextraction (SDME), followed by gas chromatography with a nitrogen-phosphorus detector, was assessed for determining carbamates and organophosphorus pesticides in natural water. Experimental parameters which control the performance of SDME such as selection of microextraction solvent, optimization of organic drop volume, effects of sample stirring, salt addition, and, finally, sorption time profiles were studied. Once SDME was optimized, analytical parameters such as linearity (r 2>0.99), precision (<13%), and detection limits (0.2 to 5 microg/L), plus matrix effects were evaluated (no matrix effects were found). SDME is a dynamic technique able to extract pesticides from water in 14 min; the use of organic solvents and water samples for SDME is negligible compared to other extraction techniques.

Determination of carbamate insecticides in Chinese medicinal herbs by gas chromatography with a nitrogen-phosphorus detector

A simplified method for determining carbamate insecticides (including metolcarb, isoprocarb, fenobucarb, carbofuran, pirimicarb, and carbaryl) in Chinese medicinal herbs (White Peony Alba, Red Peony Root, and Baical Skullcap Root) is described. Standards were fortified into Chinese medicinal herbs at 3 levels (0.05-0.5 mg/kg). The carbamates were extracted with dichloromethane in a Soxhlet apparatus and analyzed by gas chromatography with a nitrogen-phosphorus detector. The results showed average recoveries between 80.77 and 104.56%. The method evidenced good robustness, accuracy, and precision for monitoring carbamates in Chinese medicinal herb samples, and it is a suitable alternative to replace the currently dedicated analytical systems. The minimum detectable amount ranged from 3.0 x 10(-10) to 5.0 x 10(-10)g, and the limit of quantification was 0.05 mg/kg. The method is rapid, simple, sensitive, and reproducible, and it can be conveniently used as a low-cost, rapid method for measuring the carbamate insecticide contamination of Chinese medicinal herbs.

[HPLC separation of racemic basic esters of alkoxyphenylcarbamic acid using two teicoplanin chiral stationary phases]

This paper presents the results obtained with the use of two chiral stationary phases (CSP), based on a glycopeptide antibiotic agent--teicoplanin aglycone (CHIROBIOTIC TAG) and methylated teicoplanin aglycon m-TAG. Twenty-one racemic mixtures of 1-methyl-2-piperidinoethylesters of 2-, 3- and 4-alkoxyphenylcarbamic acid were examined. The investigation included interaction between separated substances and CSP, and the effect of separation of the enantiomers under study on the value of the resolution factor (R(ij)) under identical chromatographic conditions with the use of the method of high-performance liquid chromatography (HPLC). On the basis of obtained results, it is possible to report that CSP-CHIROBIOTIC TAG is more advantageous for these racemates, because it does not contain a saccharide part, with decrease the possibility of non-polar interactions which exert a negative effect on the R(ij) value.

Fluorescence enhancement of Carbendazim in the presence of cyclodextrins and micellar media: a reappraisal

This study focuses on the spectrofluorimetric behavior of the pesticide carbendazim in the presence of selected organized assemblies and also on their potential analytical applications. The relatively weak fluorescence emission band of carbendazim is significantly enhanced by micellar media formed by sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and decyltrimethylammonium bromide. The influence of the surfactant structures, concentrations, and working experimental conditions on the fluorescence spectra of carbendazim was thoroughly evaluated and discussed. Although the interaction of carbendazim with different cyclodextrins is rather weak, it was corroborated that the fluorescence intensity of this compound in the presence of (2-hydroxy)propyl beta-cyclodextrin is increased by a factor of two. Among the studied organized media, the cationic surfactant hexadecyltrimethylammonium bromide produced the largest signals for the compound of interest. Consequently, the optimal working conditions for the spectrofluorimetric determination of carbendazim in the presence of the latter detergent were analyzed, concluding that previous literature reports should be reconsidered.

Disposable biosensor test for organophosphate and carbamate insecticides in milk

A highly sensitive and rapid biosensor test based on disposable screen-printed thick-film electrodes was developed, which is suitable for monitoring organophosphate and carbamate residues in foods of animal origin with increased fat contents such as milk. The wild-type enzyme was combined with three engineered variants of Nippostrongylus brasiliensis acetylcholinesterase (NbAChE), to obtain enhanced sensitivity. The sample pretreatment could be reduced to a minimum. There was no extraction or fat removal necessary. With the biosensor test paraoxon concentrations down to 1 microg/L could be detected in milk. The detection limit for carbaryl was 20 microg/L. Recovery rates for paraoxon and carbaryl in milk samples lay between 89 and 107%. Ten milk samples from local markets were tested both with the biosensor test and with standard chromatographic multiresidue methods. Two milk samples caused AChE inhibition rates of >50%. Accordingly, 4 microg/L tebufenpyrad, 4 microg/L tetraconazole, and 2 microg/L bifenthrin were detected in one of these milk samples. The other milk sample contained 2 microg/L tebufenpyrad.

The use of biomarkers of exposure of N,N-dimethylformamide in health risk assessment and occupational hygiene in the polyacrylic fibre industry

BACKGROUND

N,N-dimethylformamide (DMF) was recently prioritised for field studies by the National Toxicology Program based on the potency of its reproductive toxic effects.

AIMS

To measure accurately exposure to DMF in occupational settings.

METHODS

In 35 healthy workers employed in the polyacrylic fibre industry, N-methylformamide (NMF) and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) in urine, and N-methylcarbamoylated haemoglobin (NMHb) in blood were measured. Workplace documentation and questionnaire information were used to categorise workers in groups exposed to low, medium, and high concentrations of DMF.

RESULTS

All three biomarkers can be used to identify occupational exposure to DMF. However, only the analysis of NMHb could accurately distinguish between workers exposed to different concentrations of DMF. The median concentrations were determined to be 55.1, 122.8, and 152.6 nmol/g globin in workers exposed to low, medium, and high concentrations of DMF, respectively. It was possible by the use of NMHb to identify all working tasks with increased exposure to DMF. While fibre crimpers were found to be least exposed to DMF, persons washing, dyeing, or towing the fibres were found to be highly exposed to DMF. In addition, NMHb measurements were capable of uncovering working tasks, which previously were not associated with increased exposure to DMF; for example, the person preparing the fibre forming solution.

CONCLUSIONS

Measurement of NMHb in blood is recommended rather than measurement of NMF and AMCC in urine to accurately assess exposure to DMF in health risk assessment. However, NMF and AMCC are useful biomarkers for occupational hygiene intervention. Further investigations regarding toxicity of DMF should focus on highly exposed persons in the polyacrylic fibre industry. Additional measurements in occupational settings other than the polyacrylic fibre industry are also recommended, since the population at risk and the production volume of DMF are high.

Flow-through fluorescence-based optosensor with on-line solid-phase separation for the simultaneous determination of a ternary pesticide mixture

A rapid and selective method was developed for the simultaneous determination of 3 widely used pesticides, carbendazim (CBZ), carbofuran (CF), and benomyl (BNM). The method utilized a single continuous-flow, solid surface fluorometric multioptosensor implemented with a previous separation of the analytes on a minicolumn, placed just before the sensor, that was packed with the same solid support (C18 silica gel) as the flow-through cell. The separation was achieved because of the different kinetics of retention/elution of the pesticides on the solid support in the minicolumn, enabling the sequential arrival of the analytes at the sensing zone. With a single injection of the mixture, 2 of them were more strongly retained in the minicolumn (CF and BNM) while the other (CBZ) passed through the system towards the sensing material where it developed its fluorescence transitory signal. Then, CF and BNM were successively eluted from the solid support using 2 different eluting solutions, and they sequentially reached the sensing zone and developed their respective signals. A multiwavelength fluorescence detection mode was used, recording the signals of each pesticide at its maximum excitation/emission wavelength; therefore, the sensitivity was increased. The system was calibrated using a sample volume of 2000 microL. The linear dynamic range was 80-1400, 250-2400, and 150-2000 ng/mL with detection limits of 15, 68, and 35 ng/mL and relative standard deviation values of 3.5, 3.2, and 2.4% for CBZ, CF, and BNM, respectively. A recovery study was applied to spiked environmental water samples, and recoveries ranged from 96 to 104%.

Screening and evaluation of fruit samples for four pesticide residues

The occurrence of 4 pesticide residues, imidacloprid, carbendazim, methiocarb, and hexythiazox, was assessed in several fruits (oranges, tangerines, watermelons, and date plums) from the Valencian Community (Spain). A total of 227 samples--56 oranges, 134 tangerines, 13 watermelons, and 24 date plums--were taken from an agricultural cooperative representative of the area studied during 2001. The pesticides were determined by liquid chromatography/mass spectrometry after sample extraction with ethyl acetate and anhydrous sodium sulfate. Recoveries of 4 pesticides at 2 fortification levels (0.02 and 0.2 mg/kg), the lower of which was the quantification limit, ranged from 60 to 108%. Concentrations of imidacloprid, carbendazim, methiocarb, and hexythiazox ranged from 0.02 to 0.75 mg/kg in 184 samples (54 oranges, 119 tangerines, 3 watermelons, and 8 date plums). Nineteen samples contained methiocarb or hexythiazox residues that exceeded the maximum residue limits. Calculation of the estimated daily intakes of the 4 pesticides studied and their comparison with the Acceptable Daily Intakes established by the Food and Agriculture Organization of the World Health Organization demonstrated the safety of fruit consumption and showed the importance of monitoring for pesticide residues.

Monitoring of antifouling booster biocides in water and sediment from the port of Osaka, Japan

Concentrations of booster antifouling compounds in the port of Osaka, Japan were assessed. Concentrations of Sea-Nine 211 (4,5-dichloro-2-n-octyl-3-isothiazolone), thiabendazole (2-(4-thiazolyl)-benzimidazole), IPBC (3-iodo-2-propynyl butylcarbamate), Diuron (3,4-dichlorophenyl-N, N-dimethylurea), Irgarol 1051 (2-methylthio-4-t-butylamino-6-cyclopropylamino-s-triazine), and M1 (2-methylthio-4-t-butylamino-6-amino-s-triazine) in port water samples were in the range of <0.003-0.004 microg L(-1), <0.0008-0.020 microg L(-1), <0.0007-1.54 microg L(-1), <0.0008-0.267 microg L(-1), and <0.0019-0.167 microg L(-1), respectively. IPBC was not detected in the water samples, but the concentration of Diuron was higher than any previously reported. The concentrations of Sea-Nine 211, thiabendazole, Diuron, Irgarol 1051, and M1 in sediment samples were in the range of <0.04-2.4 microg kg(-1) dry, <0.08-1.2 microg kg(-1) dry, <0.64-1350 microg kg(-1) dry, <0.08-8.2 microg kg(-1) dry, and <0.18-2.9 microg kg(-1) dry, respectively. IPBC was again not detected. The levels of Sea-Nine 211, Diuron, and Irgarol 1051 in water and sediment samples were high in a poorly flushed mooring area for small and medium-hull vessels. Levels of Diuron and Irgarol 1051 were highest in summer. The concentration of Sea-Nine 211 in water increased between August and October 2002. Except for M1, increases in the levels of booster biocides in sediment were observed during the study period. The sediment-water partition (Kd) was calculated by dividing the concentrations in sediment by the concentrations in water. The Kd values for Sea-Nine 211, thiabendazole, Diuron, Irgarol 1051, and M1 were 690, 180, 2700, 300, and 870. The Kd value for these alternative compounds was lower than for TBT.

Determination of pirimicarb and endosulfan in commercial pesticide formulations by Fourier transform infrared spectrometry

A routine method based on Fourier transform infrared spectrometry was developed for the simultaneous determination of pirimicarb and endosulfan in commercially available pesticide formulations. The method is based on peak area absorbance measurements between 1362 and 1352 cm(-1), corrected with a baseline fixed at 1338 cm(-1), for pirimicarb and peak area absorbance measurements between 919 and 909 cm(-1) with a baseline fixed at 931 cm(-1) for endosulfan; chloroform solutions for analysis were obtained by direct dilution of emulsifiable concentrates or by solvent extraction from solid samples. Various extraction conditions and appropriate band selection were investigated, and interference studies were performed. Under the experimental conditions selected, limits of detection of 13 microg/g for pirimicarb and 150 microg/g for endosulfan were obtained that correspond to 0.13 and 1.6% (w/w), respectively, in commercial samples. Results from analyses of commercial samples by the developed method compared well with those obtained by a liquid chromatography reference method.

Combining solid-phase microextraction and on-line preconcentration-capillary electrophoresis for sensitive analysis of pesticides in foods

The combined use of solid-phase microextraction (SPME) and different on-line preconcentration strategies for ultrasensitive capillary electrophoresis-ultraviolet (CE-UV) analysis of five pesticides in a single run is investigated. Normal stacking mode (NSM), field-enhanced sample injection (FESI), and stacking with matrix removal (SWMR) are explored to increase the sensitivity of the CE-UV analysis of a selected group of pesticides (cyprodinil, cyromazine, pyrifenox, pirimicarb, and pyrimethanil). It could be observed that reverse polarity-stacking with matrix removal (RP-SWMR) provided the best results in terms of sensitivity (enhancement was up to 272-fold compared with normal injection). The separation buffer consisted of 0.4 mM cetyltrimethylammonium chloride (CTAC), 0.4 M acetic acid at pH 4 containing 5% v / v 2-propanol. This approach was then combined with SPME to determine the pesticides in water, apple, and orange juice. The combination of both preconcentration procedures allowed the determination of these pesticides at concentrations down to 2.5 microg / L in water and 3.1 microg / L in juices (i.e., levels well below the maximum residue limits allowed for these compounds). To our knowledge, this is the first report showing the great possibilities of the combined use of SPME, on-line sample preconcentration, and CE for pesticide analysis.

Liquid chromatographic determination of nineN-methylcarbamates in drinking water

A multi-residue method for the simultaneous extraction from drinking water using solid-phase extraction on LiChrolut EN [poly(styrene-divinylbenzene), PSDVB] and determination of nine N-methylcarbamate pesticides (NMCs) (aldicarb, its metabolites i.e. aldicarb sulfone and aldicarb sulfoxide and carbaryl, carbofuran, dioxacarb, ethiofencarb, methomyl and propoxur) using reversed-phase liquid chromatography was studied. A 1000-fold pre-concentration was achieved and the method was used for determination of the nine pesticides in water, with limits of detection in the range 3-15 ng L(-1). For all compounds the recoveries determined at the 0.1 and 1 microg L(-1) level generally ranged from 85 to 104% with relative standard deviations (RSD) of 1.4-8.8%.

Analytical methods used in the United Kingdom Wildlife Incident Investigation Scheme for the detection of animal poisoning by pesticides

The United Kingdom Wildlife Incident Investigation Scheme (WIIS) investigates cases of suspected poisoning of wildlife, honey bees, and companion animals by pesticides. Together with field inquiries and veterinary post-mortem examinations, the analytical procedures presented here provide a comprehensive approach to the investigation of these cases. The paper covers selection of animal tissues for analysis and methods suitable for the analysis of honey bees and for various types of bait. Seven multiresidue methods cover around 130 pesticides, and methods are also described for a further 8 compounds. These methods are currently used on samples submitted to the Scheme in England and Wales.

Evaluation of cyclodextrins modified with dichloro-, dimethyl-, and chloromethylphenylcarbamate groups as chiral stationary phases for capillary electrochromatography

Capillary electrochromatography using cyclodextrins modified with dichloro-, dimethyl-, and chloromethylcarbamate groups were used for the enantiomeric separation of standard analytes. The chiral selector was chemically bonded to aminopropylsilanized silica particles, and these chiral stationary phases (CSPs), mixed with aminopropylsilanized silica (1:1 wt:wt), were packed into 100-microm-i.d. fused-silica capillaries. The effect of the type of cyclodextrin, the nature and position of the substituents on the phenyl ring, and the binding mode of cyclodextrin phenylcarbamates onto the silica gel surface on the chiral recognition were studied. Experimental parameters such as organic solvent concentration were varied in order to better understand the mechanism contributing to the chiral recognition of these CSPs. Good enantioseparations were achieved for a racemic flavanone (FLA) and trans-cyclopropanedicarboxylic acid dianilide (CAD).

Effect of tank mixed adjuvants on the drift potential of phenmedipham formulations

The aim of this paper is to analyse the effect of adjuvants and formulations on drift. The spray liquids consisted of four adjuvants (Actirob 0.4 %, Tensiofix 0.2%, Breakthru 0.2%, Silwet L-77 0.1%) with water and with two formulations of Phenmediphame (C16H16N2O4, 4.45%): an emulsion-forming (EC) and a suspension concentrate (SC). A standard flat fan nozzle at a pressure of 3 bar was used. The droplet size spectrum of each combination was determined using a Malvern granulometer. The droplet size was characterized by the volume median diameter (VMD) and the percentage of spray volume contained in droplets <100 microm (%<100). The relative drift potential was measured for each combination of formulation and adjuvant in a wind-tunnel. This latter has a working section 2.0 m wide by 2.0 m high by 6.0 m long. The air-stream is drawn by a 1.2 m diameter axial flow fan, powered by a 22 kW electric motor. Wind speed was 5 m/s. Its uniformity was controlled by a three-dimensional sonic anemometer able to move on a linear translation beam placed in the tunnel cross section. The wind-tunnel was operated under ambient conditions and three repetitions were performed randomized in order to eliminate variations in temperature and humidity for each combination. The ground spray deposits were measured on glass fibber collectors using a fluorescent tracer dye (sodium fluorescein), at a concentration of 2.5 mg/l. The statistical analysis of the droplet spectrum showed that the Phenmediphame SC formulation generated droplets of higher size than the EC. The mean VMD values were respectively equal to 228+/-11 microm and 185+/-11 microm for these formulations. For SC formulation, Break-thru decreased the VMD while Tensiofix increased the %<100. This confirmed that the degree to which an adjuvant influences spray characteristics is very variable. The drift profiles produced by the different combinations were similar, but the relative drift potential was significantly different comparing SC and EC formulations: it respectively reached 0.8+/-0,08% and 1.2+/-0,08%, whatever the adjuvant used in the liquid. Clearly, when using a flat fan nozzle to spray Phenmediphame, the droplet size and the drift potential are mainly governed by the kind of formulation, even if an interaction between the formulation and the adjuvant exists.