Improved cleanup technique for the estimation of endosulfan and endrin residues.

An improved cleanup technique has been developed for the extraction of endosulfan and endrin from crops. The technique involves the use of Nuchar C-190N as adsorbent and a mixture of n-hexane and acetone (4+1) as the eluting solvent. The mean percentage recoveries of endosulfan (I and II) and endrin from plant tissue extracts fortified at levels of 0.5-2.0 ppm varied from 86 to 102 and 97 to 100, respectively.     

Multiresidue method for determination of 35 pesticides in virgin olive oil by using liquid-liquid extraction techniques coupled with solid-phase extraction clean up and gas chromatography with nitrogen phosphorus detection and electron capture detection

A method for the multiresidue determination of 35 pesticides (30 insecticides and five herbicides) in olive oil by gas chromatography (GC) is described. Three liquid-liquid extraction (LLE) procedures based on (i) partition of pesticides between acetonitrile (ACN) and oil solution in n-hexane, (ii) partition of pesticides between saturated ACN with n-hexane and oil solution in n-hexane saturated with ACN, and (iii) partition of pesticides between ACN and oil were tested for the optimization of the highest pesticide recoveries with the lowest oil residue in the final extracts. Experimental tests were preformed in order to study the efficiency of different clean up procedures with N-Alumina, Florisil, C18, and ENVI-Carb solid-phase extraction (SPE) cartridges for the compounds analyzed by GC-nitrogen phosphorus detection. A second step of clean up was also performed for the compounds analyzed by GC-electron capture detection (ECD), by using phenyl-bonded silica (Ph), diol-bonded silica (Diol), cyanopropyl-bonded silica (CN), and amino propyl-bonded silica (NH2) SPE cartridges. LLE of the oil solution in hexane with ACN followed by an ENVI-Carb SPE clean up of the extract gave the best results for all target compounds. The ACN extract was additionally cleaned through a Diol-SPE cartridge for the determination of pesticides analyzed mainly by GC-ECD. Pesticide recoveries form virgin olive oil spiked with 20, 100, and 500 microg/kg concentrations of pesticides ranged from 70.9 to 107.4%. The proposed method featured good sensitivity, pesticide quantification limits were low enough, and the precision, expressed as relative standard deviation, ranged from 2.4 to 12.0%. The proposed method was applied successfully for the residue determination of the selected pesticides in commercial olive oil samples.     

Simplified cleanup and gas chromatographic determination of organophosphorus pesticides in crops

A simple and efficient cleanup method for gas chromatographic determination of 23 organophosphorus pesticides in crops including onion is described. The sample was extracted with acetone. The extract was purified with coagulating solution, which contained ammonium chloride and phosphoric acid, and then filtered by suction. The filtrate was diluted with NaCl solution and reextracted with benzene. The organic layer was evaporated and injected into a gas chromatograph equipped with a flame photometric detector (FPD) and fused silica capillary columns (0.53 mm id) coated with silicone equivalent to OV-1701, OV-1, and SE-52. Onion extract, which contained FPD interferences, was cleaned up on a disposable silica cartridge. Recoveries of most organophosphorus pesticides from spiked crops: mandarin orange, tomato, spinach, sweet pepper, broccoli, lettuce, and onion at levels of 0.02-0.28 ppm, exceeded 80%, but the water-soluble pesticides dichlorvos and dimethoate gave poor recoveries in all crops; the nonpolar pesticides disulfoton, chlorpyrifos, fenthion, prothiophos, and leptophos were not recovered quantitatively in spinach, sweet pepper, broccoli, and lettuce. IBP, edifenphos, phosmet, and pyridaphenthion were not recovered from onion because of adsorption to the silica cartridge. The detection limits ranged from 1.25 to 17.5 ppb on a crop basis.     

Extraction and determination by gas chromatography of S,S,S-tri-n-butyl phosphorotrithioate (DEF) in fish and water

A simple, low-cost, fast method for the extraction and cleanup of DEF (S,S,S-tri-n-butyl phosphorotrithioate) from fish tissues and water samples was developed. The method combines extraction and cleanup in one step. The basis of the method is passing water samples or aqueous tissue homogenates containing DEF through a C-18 disposable cartridge. DEF is eluted from the cartridge by acetone or ethyl acetate. The eluates are analyzed by gas chromatography using a thermionic-specific detector. The method detects levels as low as 100 parts per trillion (ppt) in water samples; recovery efficiency from spiked fish tissues was greater than 95%. In addition, detectable levels of DEF were recovered from liver, brain, and muscle tissue of fish exposed to this compound. The method has a potential for use with other pesticides.     

Development of green onion and cabbage certified reference materials for quantification of organophosphorus and pyrethroid pesticides

Green onion and cabbage certified reference materials for the analysis of pesticide residues were issued by the National Metrology Institute of Japan, part of the National Institute of Advanced Industrial Science and Technology. Green onion and cabbage samples were grown so as to contain several kinds of organophosphorus and pyrethroid pesticides, and those were collected from a field in the Kochi Prefecture in Japan. The certification was carried out by using multiple analytical methods to ensure the reliability of analytical results; the values of target pesticides (diazinon, fenitrothion, cypermethrin, etofenprox, and permethrin for green onion and chlorpyrifos, fenitrothion, and permethrin for cabbage) were obtained by isotope dilution mass spectrometry. Certified values of target pesticides were 0.96-13.9 and 2.41-6.9 mg/kg for green onion and cabbage, respectively. These are the first green onion and cabbage powder certified reference materials in which organophosphorus and pyrethroid pesticides are determined.     

Extraction of polyphenols from vine shoots of Vitis vinifera by superheated ethanol-water mixtures

A study of the nonvolatile fraction of extracts from vine shoots obtained by superheated ethanol-water mixtures is presented. The influence of the temperature, extraction time, and percentage of ethanol on extraction was investigated by a multivariate experimental design to maximize the yield of total phenolic compounds, measured by using the Folin-Ciocalteu method. The best values found for these variables were 80% (v/v) ethanol, 240 degrees C, and 60 min. Under these conditions, the effect of pH was also investigated, and a strong improvement of yield was observed by decreasing the pH. The extracts were subject to liquid-liquid extraction with n-hexane. The remaining polar phase was dried in a rotary evaporator and then reconstituted in 10 mL of water. The insoluble residue was dissolved in 10 mL of methanol. Both fractions (aqueous and methanolic) were analyzed by HPLC, and the differences in composition according to the extraction conditions were studied. Compounds usually present in commercial wood extracts were identified (mainly benzoic and hydroxycinnamic acids and aldehydes); the most abundant were quantified, and the stability of the identified phenolic families under different extraction conditions was also investigated. Finally, the superiority of the superheated liquid extraction over conventional solid-liquid extraction was demonstrated.     

Determination of acetamiprid,imidacloprid, and nitenpyram residues in vegetables and fruits by high-performance liquid chromatography with diode-array detection

Determination of 3 neonicotinoid insecticides, nitenpyram, imidacloprid, and acetamiprid, was studied. Vegetables and fruits were extracted with acetonitrile. The crude extract was passed through a weak anion-exchange cartridge (PSA). The effluent was subjected to silica gel cartridge. Imidacloprid and acetamiprid were eluted with 10 mL of 4:6 (v/v) acetone/hexane, followed by nitenpyram with acetone (20 mL). Pesticides were determined by HPLC with a C-18 column and diode-array detection system. Imidacloprid and acetamiprid were recovered at about 90% at the spike levels with 0.2 and 2 mg/kg in cucumber, potato, tomato, eggplant, Japanese radish, and grape. Nitenpyram was recovered at 64-80%. Relative standard deviations were less than 10% throughout all the recovery tests. In the residue analysis, agriculturally incurred pesticides at 0.08-0.14 mg/kg were designated with UV spectra compared with respective reference standards.     

Determination of 49 organophosphorus pesticide residues and their metabolites in fish, egg, and milk by dual gas chromatography-dual pulse flame photometric detection with gel permeation chromatography cleanup

A new method for the quantitative determination of 49 kinds of organophosphorus pesticide residues and their metabolites in fish, egg, and milk by dual gas chromatography-dual pulse flame photometric detection was developed. Homogenized samples were extracted with acetone and methylene chloride (1 + 1, v/v), and then the extracts were cleaned up by gel permeation chromatography (GPC). The response of each organophosphorus pesticide showed a good linearity with its concentration; the linearity correlation was not less than 0.99. The detection limits (S/N = 3) of pesticides were in the range of 0.001-0.025 mg kg?1. The recovery experiments were performed by blank sample spiked at low, medium, and high fortification levels. The recoveries for fish, egg, and milk were 50.9-142.2, 53.3-137.2, and 50.3-139.4% with relative standard deviations (RSD, n = 6) of 2.3-24.9, 4.3-26.7, and 2.8-32.2%, respectively. The method was applied to detect organophosphorus pesticides in samples collected from the market, and satisfactory results were obtained. This quantitative method was highly sensitive and exact and could be applied to the accurate determination of organophosphorus contaminants in fish, egg, and milk.     

Comparison of accelerated methods for the extraction of phenolic compounds from different vine-shoot cultivars

Most research on the extraction of high-priced compounds from vineyard/wine byproducts has traditionally been focused on grape seeds and skins as raw materials. Vine-shoots can represent an additional source to those materials, the characteristics of which could depend on the cultivar. A comparative study of hydroalcoholic extracts from 18 different vineyard cultivars obtained by superheated liquid extraction (SHLE), microwave-assisted extraction (MAE), and ultrasound-assisted extraction (USAE) is here presented. The optimal working conditions for each type of extraction have been investigated by using multivariate experimental designs to maximize the yield of total phenolic compounds, measured by the Folin-Ciocalteu method, and control hydroxymethylfurfural because of the organoleptic properties of furanic derivatives and toxicity at given levels. The best values found for the influential variables on each extraction method were 80% (v/v) aqueous ethanol at pH 3, 180 °C, and 60 min for SHLE; 140 W and 5 min microwave irradiation for MAE; and 280 W, 50% duty cycle, and 7.5 min extraction for USAE. SHLE reported better extraction efficiencies as compared to the other two approaches, supporting the utility of SHLE for scaling-up the process. The extracts were dried in a rotary evaporator, reconstituted in 5 mL of methanol, and finally subjected to liquid-liquid extraction with n-hexane to remove nonpolar compounds that could complicate chromatographic separation. The methanolic fractions were analyzed by both LC-DAD and LC-TOF/MS, and the differences in composition according to the extraction conditions were studied. Compounds usually present in commercial wood extracts (mainly benzoic and hydroxycinnamic acids and aldehydes) were detected in vine-shoot extracts.     

Degradation of Prototype Pesticides Submitted to Conventional Water Treatment Conditions: The Influence of Major Parameters

The behavior of several pesticides in aqueous solution, namely bifenthrin, amethrin (pyrethroid insecticides), endosulfan and endosulfan sulfate (organochlorine pesticides), disulfoton, methyl pyrimiphos, and phorate (organophosphorus pesticides), submitted to the conditions typically employed in water treatment stations was investigated. Continuous pesticide depletion was monitored by solid-phase microextraction sampling followed by gas chromatography–mass spectrometry analysis. The influence of major parameters (sodium hypochloride concentration, solution pH, and exposure time to ultraviolet (UV) light) was, thus, adequately established via two complementary approaches: factorial (2³, three variables—two levels) and Doehlert designs. Hence, the sodium hypochloride concentration and the solution pH produced distinct effects depending on the pesticide evaluated (for instance, acidic and basic media caused increasing rates of degradation for the organophosphorus/pyrethroid and organochlorine pesticides, respectively). Conversely, higher rates of degradation were achieved for all of the pesticides investigated when increased exposure times to UV radiation were employed. Finally, the exposure time to UV radiation that lead to complete degradation of disulfoton and endosulfan sulfate (organophosphorus and organochlorine pesticides, respectively) in aqueous media under ordinary conditions employed in water treatment stations was established; disulfoton and endosulfan sulfate were completely degraded after 10 and 40 h, respectively.     

Multiresidue analysis of pesticides in soil by supercritical fluid extraction/gas chromatography with electron-capture detection and confirmation by gas chromatography-mass spectrometry

The applicability of supercritical fluid extraction (SFE) in pesticide multiresidue analysis (organohalogen, organonitrogen, organophosphorus, and pyrethroid) in soil samples was investigated. Fortification experiments were conducted to test the conventional extraction (solid-liquid) and to optimize the extraction procedure in SFE by varying the CO2 modifier, temperature, extraction time, and pressure. The best efficiency was achieved at 400 bar using methanol as modifier at 60 degrees C. For the SFE method, C-18 cartridges were used for the cleanup. The analytical screening was performed by gas chromatography equipped with electron-capture detection (ECD). Recoveries for the majority of pesticides from spiked samples of soil at different residence times were 1, 20, and 40 days at the fortification level of 0.04-0.10 mg/kg ranging from 70 to 97% for both methods. The detection limits found were <0.01 mg/kg for ECD, and the confirmation of pesticide identity was performed by gas chromatography-mass spectrometry in a selected-ion monitoring mode. Multiresidue methods were applied in real soil samples, and the results of the methods developed were compared.     

Extraction and cleanup of organochlorine, organophosphate, organonitrogen, and hydrocarbon pesticides in produce for determination by gas-liquid chromatography.

A rapid, multiresidue procedure utilizing the minimal cleanup necessary for gas-liquid chromatographic (GLC) analysis is presented. The samples are extraced with acetone and partitioned with methylene chloride-petroleum either to remove water. The organophosphorus and organonitrogen compounds are then quantitated by GLC, using a KCl thermionic detector. A Florisil cleanup of the extract is performed prior to the determination of organochlorine compounds by a GLC electron capture detector. Carbon-hydrogen compounds such as biphenyl and o-phenylphenol undergo the Florisil cleanup and may also be quantitated by GLC. Quantitative recoveries for 15 organophosphorus, 9 organochlorine, 5 organonitrogen, and 2 hydrocarbon pesticides show the range in polarities of pesticides recovered, from Monitor to biphenyl. The method is simple and fast with a great potential for the analysis of many more compounds.     

Supercritical fluid extraction of organochlorine pesticides in eggs

The efficacy of supercritical fluid extraction (SFE) for the recovery of 16 common organochlorine pesticides (OCPs) from liquid whole eggs was investigated by employing supercritical carbon dioxide (SC-CO(2)) without the use of a solvent modifier to minimize interfering coextractives. The OCPs tested included aldrin; alpha-, beta-, delta-, and gamma-BHCs; p,p'-DDD, -DDE, and -DDT; dieldrin; endosulfans I, II, and sulfate; endrin; endrin aldehyde; heptachlor; and heptachlor epoxide. The SFE conditions were as follows: 10000 psi (680 bar), 40 degrees C, SC-CO(2) flow rate of 3.0 L/min with an extraction time of 40 min for a total of 120 L of CO(2). The OCPs were trapped off-line in an SPE cartridge containing Florisil and then eluted by an acetone/hexane mixture and analyzed by gas chromatography-electron capture detection (GC-ECD). Recovery studies were carried out on homogenized eggs fortified at the 0.05, 0.10, and 0.20 ppm levels. At the lowest level, 0.05 ppm, recoveries ranged from 81.8 to 108.3%, with CVs < 9.8%. All recoveries were significantly higher than those obtained by an AOAC/FDA solvent extraction method. Eggs containing incurred endosulfan I were also effectively extracted by SFE. This study suggests that the application of SFE for the extraction of OCPs from eggs will result in significant savings in analysis time and lower solvent use and disposal costs compared to conventional solvent extraction procedures.     

Total lipid extraction of homogenized and intact lean fish muscles using pressurized fluid extraction and batch extraction techniques

The reliability and efficiency of pressurized fluid extraction (PFE) technique for the extraction of total lipid content from cod and the effect of sample treatment on the extraction efficiency have been evaluated. The results were compared with two liquid-liquid extraction methods, traditional and modified methods according to Jensen. Optimum conditions were found to be with 2-propanol/n-hexane (65:35, v/v) as a first and n-hexane/diethyl ether (90:10, v/v) as a second solvent, 115 degrees C, and 10 min of static time. PFE extracts were cleaned up using the same procedure as in the methods according to Jensen. When total lipid yields obtained from homogenized cod muscle using PFE were compared yields obtained with original and modified Jensen methods, PFE gave significantly higher yields, approximately 10% higher (t test, P < 0.05). Infrared and NMR spectroscopy suggested that the additional material that inflates the gravimetric results is rather homogeneous and is primarily consists of phospholipid with headgroups of inositidic and/or glycosidic nature. The comparative study demonstrated that PFE is an alternative suitable technique to extract total lipid content from homogenized cod (lean fish) and herring (fat fish) muscle showing a precision comparable to that obtained with the traditional and modified Jensen methods. Despite the necessary cleanup step, PFE showed important advantages in the solvent consumption was cut by approximately 50% and automated extraction was possible.     

Thin layer chromatographic detection and indirect gas chromatographic determination of three carbamate pesticides.

Carbamate pesticide residues are extracted from vegetables and fruits with methylene chloride. The extracts are spotted on silica gel plates and the pesticides are detected by an enzymatic inhibition technique. For quantitative determination, aliquots of the methylene chloride extracts are evaporated to dryness in a rotary evaporator. After the residues are dissolved in ethanol, 0.5N NaOH is added in the hydrolysis step. To remove a number of possible interferences the hydrolyzed phenols are steam-distilled and treated with 1-fluoro-2,4-dinitrobenzene and/or 4-chloro-alpha,alpha,alpha-trifluoro-3,5-dinitrotoluene to form the ether derivatives. Efficiency in the conversion of the phenolic moieties to the phenyl ethers is about 100%. The resulting electron-capturing derivatives enable the carbamate pesticides to be detected in vegetables and fruits at the 0.05 ppm level. Recoveries of 90-94% were obtained from vegetables and fruits fortified with 0.5-2.0 ppm carbaryl, Mesurol, and propoxur.     

Simultaneous determination of ethidimuron, methabenzthiazuron, and their two major degradation products in soil

An analytical method has been developed for the quantification of two herbicides (ethidimuron and methabenzthiazuron) and their two main soil derivatives. This method involves fluidized-bed extraction (FBE) prior to cleanup and analysis by reverse-phase liquid chromatography with UV detection at 282 nm. FBE conditions were established to provide efficient extraction without degradation of the four analytes. (14)C-labeled compounds were used for the optimization of extraction and purification steps and for the determination of related efficiencies. Extraction was optimal using a fexIKA extractor operating at 110 degrees C for three cycles (total time = 95 min) with 75 g of soil and 150 mL of a 60:40 v/v acetone/water mixture. Extracts were further purified on a 500 mg silica SPE cartridge. Separation was performed on a C18 Purosphere column (250 mm x 4 mm i.d.), at 0.8 mL min(-1) and 30 degrees C with an elution gradient made up of phosphoric acid aqueous solution (pH 2.2) and acetonitrile. Calibration curves were found to be linear in the 0.5-50 mg L(-1) concentration range. Besides freshly spiked soil samples, method validation included the analysis of samples with aged residues. Recovery values, determined from spiked samples, were close to 100%. Limits of detection ranged between 2 and 3 microg kg(-1) of dry soil and limits of quantification between 8 and 10 microg kg(-1) of dry soil. An attempt to improve these performances by using fluorescence detection following postcolumn derivatization by orthophthalaldehyde-mercaptoethanol reagent was unsuccessful.     

Multiresidue determination of pesticides in malt beverages by capillary gas chromatography with mass spectrometry and selected ion monitoring

A method was developed to determine pesticides in malt beverages using solid phase extraction on a polymeric cartridge and sample cleanup with a MgSO4-topped aminopropyl cartridge, followed by capillary gas chromatography with electron impact mass spectrometry in the selected ion monitoring mode [GC-MS(SIM)]. Three GC injections were required to analyze and identify organophosphate, organohalogen, and organonitrogen pesticides. The pesticides were identified by the retention times of peaks of the target ion and qualifier-to-target ion ratios. GC detection limits for most of the pesticides were 5-10 ng/mL, and linearity was determined from 50 to 5000 ng/mL. Fortification studies were performed at 10 ng/mL for three malt beverages that differ in properties such as alcohol content, solids, and appearance. The recoveries from the three malt beverages were greater than 70% for 85 of the 142 pesticides (including isomers) studied. The data showed that the different malt beverage matrixes had no significant effect on the recoveries. This method was then applied to the screening and analysis of malt beverages for pesticides, resulting in the detection of the insectide carbaryl and the fungicide dimethomorph in real samples. The study indicates that pesticide levels in malt beverages are significantly lower than the tolerance levels set by the United States Environmental Protection Agency for malt beverage starting ingredients. The use of the extraction/cleanup procedure and analysis by GC-MS(SIM) proved effective in screening malt beverages for a wide variety of pesticides.     

Simplified extraction and cleanup for multiresidue determination of pesticides in lanolin

In the proposed method, a light petroleum solution of lanolin (wool fat) is adsorbed on diatomaceous earth in an Extrelut column, and the pesticides are eluted with acetonitrile saturated with light petroleum. After evaporation to a small volume, the extract is subjected to solid-phase extraction (SPE) on a C-18 column. The acetonitrile eluate is evaporated to dryness and the residue is taken up in light petroleum. Organophosphorus pesticides are determined by temperature-programmed gas chromatography (GC) on a wide-bore column using a flame photometric detector in the phosphorus mode. Organochlorine pesticides are determined after miniaturized Florisil cleanup by classic GC on an OV-17/QF-1 packed column, using an electron capture detector. This procedure is more rapid and straightforward than the time-consuming AOAC extraction method, 29.014. Cleanup was better and the results obtained were comparable. Recoveries for 13 organochlorine and organophosphorus pesticides, frequently found in lanolin, ranged from 80 to 90%.     

蔬菜有机磷农药多残留检测中的样品基质干扰及检测方法的适宜性

为研究NY/T 761-2004(农业行业标准)用于蔬菜有机磷农药多残留检测中的样品基质干扰问题,根据NY/T 761-2004分析众多蔬菜样品,结合气质联用技术,评估蔬菜样品基质对有机磷农药多残留分析的干扰。结果表明,用NY/T 761-2004检测蔬菜有机磷农药多残留时,绿叶菜类、白菜类、瓜类、茄果类、豆类、薯芋类和根菜类蔬菜几乎没有样品杂质峰,有机磷农药测定不受干扰;甘蓝类蔬菜(如紫甘蓝、甘蓝和西兰花等)有显著的样品杂质峰,敌敌畏、甲胺磷、甲拌磷和甲基毒死蜱等测定常受干扰;葱蒜类蔬菜(如蒜、葱和韭菜等)有较强的样品杂质峰,有机磷农药多残留测定无法进行。     

设施大棚农药污染残留调查分析

利用弗罗里矽柱净化前处理方法,采用气相色谱（GC）方式,依据保留时间和特征离子丰度比,对辽宁某地区大棚内种植黄瓜及其叶片部分样品中的有机磷类农药（粉锈宁、乐果、敌敌畏、喹硫磷、辛硫磷、噻嗪酮、甲拌磷、马拉硫磷和对硫磷）,拟除虫菊酯类农药（百菌清、氯氰菊酯、氰戊菊酯、溴氰菊酯）的残留量进行检测分析。结果表明,有机磷类农药检出种类不固定,拟除虫菊酯类农药检出情况较为稳定,有机磷和拟除虫菊酯类农药在叶片中的检出率均略高于在果实中的检出率,且在不同时期不同大棚检出情况略有差异。针对当前农药施用现状,应多注意有机磷类和拟除虫菊酯类农药的使用和监管,对于有机磷类高毒性农药应减少或停止施用,中低毒性的拟除虫菊酯类农药应加强其作用的宣传并控制其使用量,避免追求高产量而盲目过量的施用,造成不必要的污染。