Gas-liquid chromatographic determination of resmethrin in corn, cornmeal, flour, and wheat.

A gas-liquid chromatographic (GLC) method was developed for the determination of residues of resmethrin ((5-benzyl-3-furyl)methyl cis-trans-(+/-)-2,2-dimethyl-3-(2-methylpropenyl)-cyclopropanecarboxylate) in corn, cornmeal, flour, and wheat. The commodity, fortified with resmethrin, was extracted by tumbling with pentane and transferred to acetonitrile, the fat was partitioned off, and the sample was chromatographed with 3% ethyl acetate in pentane on Florisil containing 0.5% water. The resmethrin residue was determined by GLC with a flame ionization detector. The results were compared with known standards that had undergone the same cleanup procedures. The method was sensitive to concentrations of resmethrin to 0.2 ppm, recoveries averaged 83%, and reproducibility was good.     

Determination of altosid insect growth regulator in waters, soils, plants, and animals by gas-liquid chromatography.

Residues of isopropyl (2E,4E)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate (Altosid) insect growth regulator are determined in waters, soils, plants, milk, eggs, fish, shellfish, poultry and cattle tissues, blood, urine, and feces. Acetonitrile is the primary extraction solvent for all samples. Residues are extracted by high-speed blending followed by vacuum filtration. Fatty extracts are subjected to cold-temperature precipitation and filtration. Samples are cleaned up by petroleum ether partitioning and Florisil and neutral alumina chromatography. The concentrated eluants are analyzed by gas-liquid chromatography (GLC) on columns of differing polarity, using hydrogen flame ionization detectors. The identity of suspected residues is confirmed by additional GLC and by mass fragmentography. The lower limits of detection were: water samples, 0.0004-0.001 ppm; soils, blood, and urine, 0.001 ppm; forage grasses, forage legumes, and rice foliage, 0.005 ppm; and milk, eggs, fish, shellfish, poultry and cattle tissues, and feces, 0.010 ppm.     

Gas-liquid chromatographic determination of residues of methanesulfonate of n-aminobenzoic acid ethyl ester in fish.

In this gas-liquid chromatographic procedure for determining residues of methanesulfonate of m-aminobenzoic acid ethyl ester (MS-222) in fish muscle, homogenized tissue is extracted with distilled water, and proteins are removed by coagulation with trichloroacetic acid, centrifugation, and filtration. After careful pH adjustment of the filtrate, MS-222 is partitioned into benzene-ethyl ether and measured by alkali flame ionization gas chromatography. Tissues with known additions of 1-19 microgram MS-222/g were analyzed, with recoveries of 84-95%.     

Liquid chromatographic determination of rotenone in fish, crayfish, mussels, and sediments

An analytical procedure is described for determining residues of rotenone in fish muscle, fish offal, crayfish, freshwater mussels, and bottom sediments. Tissue samples were extracted with ethyl ether and extracts were cleaned up by gel permeation chromatography and silica gel chromatography. Sediment samples were extracted with methanol, acidified, partitioned into hexane, and cleaned up on a silica gel column. Rotenone residues were quantitated by liquid chromatography, using ultraviolet (295 nm) detection. Recoveries from sediment samples fortified with rotenone at 0.3 microgram/g were 80.8%, whereas recoveries from tissue samples fortified with 0.1 microgram/g ranged from 87.7 to 96.8%. Samples fortified with 0.3 microgram/g and stored at -10 degrees C for 6 months before analysis had recoveries ranging from 83.2 to 90.5%. Limits of detection were 0.025 microgram/g for sediments and 0.005 microgram/g for tissue samples.     

Extraction and cleanup procedures for determination of diarylphosphates in fish, sediment, and water samples

Methods for determination of triaryl/alkylphosphates (TAPs) in water, fish, and sediment have been extended to determination of the diarylphosphate (DAP) degradation products. DAPs were extracted from water (adjusted to pH 0.5) by use of XAD-2 resin and determined by gas-liquid chromatography as butyl esters. Recovery of diphenylphosphate (DPP) and o-, m-, p-dicresylphosphates (DoCP, DmCP, DpCP) were greater than 95% in water samples fortified at 1, 10, and 50 micrograms/L. DAPs were extracted from fish with methanol and the extracts were cleaned up on reverse phase (C18) silica cartridges. Recoveries were greater than 87% for DPP, DoCP, DmCP, and DpCP in fish muscle fortified at 50, 100, and 500 ng/g. Sediments were refluxed with aqueous methanol and DAPs were recovered by use of XAD-2 resin. Recoveries of DAPs from sediments fortified at 50 and 100 ng/g were greater than 76%. Interferences (1-10 ng/g) from phosphorus or nitrogen-containing GLC peaks prevented sub- ng/g level analysis for DAPs in sediment and fish extracts.     

Matrix solid-phase dispersion extraction and gas chromatographic determination of chloramphenicol in muscle tissue

A method based on matrix solid-phase dispersion (MSPD) was developed for the gas chromatographic (GC) determination of chloramphenicol (CAP) residues in animal muscle tissue. Muscle tissue was blended with octadecylsilyl-derivatized silica (C(18)). A column made from the C(18)/muscle tissue matrix was washed with n-hexane and acetonitrile/water (5 + 95), after which CAP was eluted with acetonitrile/water (50 + 50) and partitioned into ethyl acetate. The final extract was evaporated, and a trimethylsilyl derivative of CAP was prepared with Sylon HTP and detected by GC with an electron capture detector (ECD) and a mass spectrometer. For quantitation, the internal standard used was the meta isomer of CAP (m-CAP) for GC-ECD. Muscle tissue samples were fortified at three concentration levels. At 5, 10, and 15 microg/kg levels the respective mean recoveries were 93, 96, and 98%, and the repeatabilities were 13, 11, and 3%. The detection and quantitation limits with ECD were 1.6 and 4.0 microg/kg, respectively. No statistically significant difference was observed in the efficiency of CAP extraction from muscle tissue of various animals (bovine, porcine, and poultry) by the MSPD technique.     

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.     

A rapid gas-liquid chromatographic method for the multi-determination of antioxidants in fats, oils and dried food products

A rapid quantitative method for determining 8 antioxidants in various food products is described. Two procedures are employed. The first involves the use of a glass wood precolumn to separate 3(2)-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxytoluene, 4-hydroxymethyl-2,6-di-tert-butylphenol, and mono-tert-butylhydroquinone (TBHQ) from nonvolatile residues resulting from direct injection of diluted sample or sample extracts into the gas-liquid chromatographic (GLC) column. In the second procedure, the antioxidants TBHQ, 3,3'-thiodipropionic acid, n-propyl gallate, 2,4,5-trihydroxybutyrophenone, and nordihydroguaiaretic acid are isolated from food products by extraction with 70% ethanol. The antioxidant residues are then converted to trimethylsilyl derivatives, and determined by GLC, using a flame ionization detector. Recoveries of all 8 antioxidants from 28 food samples fortified at either 10 or 100 ppm ranged from 70 to 105%.     

Determination of hexachlorobenzene and mirex in fatty products.

A procedure is described for the isolation and cleanup of hexachlorobenzene (HCB) and mirex in fats and oils for gas-liquid chromatographic (GLC) analysis. The fat or oil is distributed on unactivated Florisil, and the HCB and mirex are eluted with acetonitrile. The pesticides are then partitioned into petroleum ether. Elution through activated Florisil with methylene chloride-hexane (20+80) is used for the final cleanup. HCB and mirex are then measured by GLC, using the appropriate electron capture conditions with a 15% OV-210 column for HCB and a 3% OV-101 column for mirex. The method demonstrates recoveries greater than 90% for HCB and mirex and allows screening at or below the 0.1 ppm level in fats with a 3 mg fat injection.     

Analytical method for the determination of atrazine and its dealkylated chlorotriazine metabolites in water using gas chromatography/mass selective detection

A multiresidue method is reported for the determination of atrazine and its dealkylated chlorotriazine metabolites in water. Water samples are buffered to pH 10 and partitioned in ethyl acetate. Final analysis is accomplished using gas chromatography/mass selective detection (GC/MSD) in the selected ion monitoring (SIM) mode. The limit of detection (LOD) is 0.050 ng and the limit of quantification (LOQ) is 0.10 ppb for 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine), 2-amino-4-chloro-6-(isopropylamino)-s-triazine (G-30033), 2-amino-4-chloro-6-(ethylamino)-s-triazine (G-28279), and 2, 4-diamino-6-chloro-s-triazine (G-28273). The mean procedural recoveries were 90, 92, 98, and 85% and the standard deviations were 12, 13, 16, and 20% for atrazine, G-30033, G-28279, and G-28273, respectively (n = 30). The study was conducted under U.S. EPA FIFRA Good Laboratory Practice Guidelines 40 CFR 160 for method validation. The reported procedure accounts for residues of G-28273 in water that are not included in EPA Method 507.     

鲮鱼对食物和水中110mAg的吸收和排泄

鲮鱼鱼苗摄食110mAg标记的人工饵料后排出十分快速 ,摄食 2 4h至第 7d后 ,鱼整体的放射性迅速降低约为 0h的 2 .62 % ,110mAg在鱼体内的分布很不均匀 ,其分布的比活度次序为肝>肠 >胆 >眼 >鳃 >剩余 >肌肉 ,肝脏、肠和胆最高 ,各占总体的 48.1 4% ,1 8.43.%和 1 5 .4%。110mAg从水中进入鱼体内的浓集系数 (CF)随积累时间的延长而上升 ,至第 1 3d上升为 2 0 8.6。排出速率相对于从食物途径的较为缓慢 ,第 1 5～ 2 8d后体内的放射性活度为 0h的 2 0 .1 %和1 6.7%。排出过程分为快相和慢相 ,0～ 2d内为快相 ,2d后为慢相 ,慢相的生物半排出期为2 2d。在积累和排泄期间110mAg在鱼体内的分布也主要积累在内脏 ,均约占总活度的 80 %。     

Mass spectrometric identification and gas-liquid chromatographic determination of 2-chloroethyl esters of fatty acids in spices and foods.

The 2-chloroethyl esters of 5 fatty acids have been identified in spice and food samples by gas-liquid chromatography-mass spectrometry (GLC/MS). Twenty-four spice samples were analyzed for the 2-chloroethyl esters of fatty acids by AOAC official multiple residues pesticide procedure using GLC with microcoulometric detection. The esters of capric, lauric, myristic, palmitic, and linoleic acids have been identified at levels up to 1400 ppm. 2-Chloroethyl linoleate was the most abundant ester in all samples. Several foods analyzed by the same procedures showed levels of 2-chloroethyl linoleate as high as 35 ppm. Recoveries from fortified samples ranged from 84 to 98% for the various esters. A method using an acid-catalyzed esterification reaction was developed to rapidly determine the fatty acid content of these spices. GLC analysis with microcoulometric detection was used. Recoveries from fortified samples ranged from 92 to 110%. After 2 spice samples found to be free of 2-chloroethyl esters were fumigated with ethylene oxide, the level of 2-chloroethyl linoleate reached 77 ppm. All levels of 2-chloroethyl esters were confirmed by GLC/MS.     

Polycyclic aromatic hydrocarbon profile analysis of high-protein foods, oils, and fats by gas chromatography.

A method is described for the determination of polycyclic aromatic hydrocarbons (PAHs) with 3-7 rings in (I) meat, poultry, fish, and yeast; and (II) oils and fats. The extraction of PAHs from group I is incomplete, and, therefore, group I samples must be dissolved homogeneously by saponification in 2N methanolic potassium hydroxide. The PAHs are concentrated by liquid-liquid extraction (methanol-water-cyclohexane, N,N - dimethylformamide - water-cyclohexane) and by column chromatography on Sephadex LH 20. The PAHs are separated by high-performance gas-liquid chromatography (GLC) with columns containing 5% OV-101 on Gas-Chrom Q and estimated by integration of the flame ionization detector signals in relation to an internal standard (3,6-dimethylphenanthrene and/or benzo(b)chrysene). The sensitivity is significantly higher than that obtained with ultraviolet spectroscopic methods. The reproducibility and margin of error were tested with meat samples fortified with 11 PAHs and with samples of sunflower oil. The method was further applied to meat, smoked fish, yeast, and unrefined sunflower oil. All samples investigated contained more than 100 PAHs (characterized by mass spectrometry) of which only the main components were determined: phenanthrene, anthracene, fluorene, fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene + benzo (j)fluoranthene + benzo(k) fluoranthene, benzo(e)pyrene, benzo(a)pyrene, perylene, dibenz(a,j)anthracene, dibenz(a,h)anthracene + indeno(1,2,3,-cd)pyrene, benzo(ghi)perylene, anthanthrene, and coronene. In contrast to other methods, the GLC profile analysis allows the recording of known and unknown PAH peaks simultaneously and also allows a compilation of all PAHs.     

Bioaccumulation of melamine in catfish muscle following continuous, low-dose, oral administration

In this study, catfish muscle was analyzed for melamine (MEL) and cyanuric acid (CYA) residues following experimental feeding with low doses of MEL and MEL and CYA (MEL+CYA) and with the insoluble melamine-cyanurate complex (MEL=CYA). Catfish were daily fed 0.1 mg/kg BW of MEL for 15, 28, or 42 days, 0.1 mg/kg BW of MEL+CYA for 28 days, 2.5 mg/kg BW of MEL+CYA for 14 days, or 400 mg/kg BW of MEL=CYA for 3 days. Residues in the tissue were determined by LC-MS/MS. MEL was extracted with acidic acetonitrile, followed by defatting with dichloromethane, and isolated with cation exchange solid phase extraction (SPE). For CYA analysis, fish were extracted with dilute acetic acid, defatted with hexane, and cleaned up with a graphitic carbon SPE. Catfish fed 0.1 mg/kg BW of MEL reached a maximum muscle residue concentration of 0.33 ± 0.04 mg/kg (ppm) after 28 days of continuous feeding. The same concentration was found for MEL+CYA feeding at the 0.1 mg/kg BW level for 28 days. Feeding at 2.5 mg/kg BW of MEL+CYA yielded muscle concentrations above the 2.5 mg/kg level of concern for most of the study fish. Finally, catfish fed high levels of the MEL=CYA complex (400 mg/kg BW) accumulated relatively little MEL in the muscle (0.14 ± 0.07 mg/kg) and, unlike treatment with MEL+CYA, did not form renal melamine-cyanurate crystals. Appreciable concentrations of CYA were not detected in any of the muscles tested. These studies provide data to model the bioaccumulation of triazine residues into edible fish tissue as a result of the continuous consumption of adulterated feed.     

Determination of chlorinated pesticide residues in foods. II. Potassium permanganate oxidation for cleanup of some vegetable extracts.

A potassium permanganate-dilute sulfuric acid KMnO4/dilute H2SO4 oxidation procedure was developed to supplement Florisil cleanup of some vegetable extracts. Following sample preparation and Florisil cleanup, a reaction mixture of the n-hexane eluate from the Florisil cleanup, 4% KMnO4, and 40% H2SO4 (1 + 1 + 1) was shaken in a test tube 2 min at room temperature and then centrifuged. The n-hexane phase was washed with 2 mL 0.1N NaOH and analyzed by GLC. Twelve chlorinated pesticides were completely recovered in the n-hexane phase. Aldrin was not recovered because its extreme instability caused it to decompose even in neutral solutions. Chlorinated pesticide residues in onion, garlic, carrot, and radish root were easily analyzed by the application of this oxidation procedure.     

Improved cleanup for gas chromatographic determination of propiconazole residues in soil, wheat grain, straw, and leaves

A simple and sensitive method is described for determination of propiconazole, a new type of broad-spectrum systemic fungicide, in soil, wheat grain, straw, and leaves. Pesticide residues in or on grain and green plant materials are extracted with methanol (or a mixture of methanol and water (4 + 1), for soil), partitioned into methylene chloride, and cleaned up on an alumina column for grain and soil or an activated charcoal column for green plant materials. The amount of residue is quantitatively measured by gas chromatography using an alkali flame ionization detector in the nitrogen-sensitive mode. Recoveries from soil, grain, and green plant materials fortified at 0.1-5 mg/kg are better than 80%. The practical detection limits of this method are 0.01 mg/kg in grain and soil and 0.02 mg/kg in green plant materials.     

Development of an enzyme-linked immunosorbent assay for seven sulfonamide residues and investigation of matrix effects from different food samples

Direct competitive enzyme-linked immunosorbent assays (ELISA) were developed to detect a broad range of sulfonamides in various matrices. Screening for this class of antibiotics in pig muscle, chicken muscle, fish, and egg extracts was accomplished by simple, rapid extraction methods carried out with only phosphate-buffered saline (PBS) buffer. Twenty milliliters of extract solution was added to 4 g of sample to extract the sulfonamide residues, and sample extracts diluted with assay buffer were directly analyzed by ELISA; matrix effects could be avoided with 1:5 dilution of pig muscle, chicken muscle, and egg extracts with PBS and 1:5 dilution of fish extract with 1% bovine serum albumin (BSA)-PBS. For liver sample, the extraction method was a little more complicated; 2 g of sample was added to 20 mL of ethanol, mixed, and then centrifuged. The solvent of 10 mL of the upper liquid was removed, and the residues were dissolved in 10 mL of PBS and then filtered; the filtrate was diluted two-fold with 0.5% BSA-PBS for ELISA. These common methods were able to detect seven sulfonamide residues such as sulfisozole, sulfathiazole, sufameter, sulfamethoxypyridazine, sulfapyridine, sulfamethizole, and sulfachlorpyridazine in pig muscle, liver, chicken muscle, egg, and fish. The assay's detection limits for these compounds were less than 100 microg kg-1. Various extraction methods were tested, and the average recovery (n=3) of 100 microg kg-1 for the matrices was found to range from 77.3 to 123.7%.     

IUPAC gas chromatographic method for determination of fatty acid composition: collaborative study.

An international collaborative study of IUPAC methods II.D.19 and II.D.25 for preparation and GLC analysis of fatty acid methyl esters was begun in 1976. The IUPAC methodology, applicable to animal and vegetable oils and fats and fatty acids from all sources, contains special instructions for preparation and analysis of methyl esters of fatty acids containing 4 or more carbon atoms (analysis of milk fat). Twenty-three collaborators participated in the analysis of 5 known mixtures, 4 vegetable oils, 1 fish oil, and 2 butterfats. Several blind duplicate samples were included. The experimental data were subjected to statistical analysis to examine intra- and interlaboratory variation. Reproducibility and accuracy data for the higher fatty acid (14:0-22:1) mixtures and fish and vegetable oils were satisfactory and were in good agreement with results from an AOCS Smalley Committee check sample program involving analysis of the same samples. Typical coefficients of variation (%) at various concentrations were 15 (2% level), 8.5 (5% level), 7 (10% level), and 3 (50% level). Low recoveries and poor reproducibility were characteristics of results obtained for butyric acid in the butterfat and related known mixtures. A coefficient of variation of about 19% was found for analysis of butyric acid in butterfat, vs coefficients of variation in the range of 4-13% for similar levels of other components in butterfat and other samples. The IUPAC methodology for GLC analysis of fats and oils other than milk fats has been adopted by the AOAC as official first action to replace the current GLC method, 28.063-28.067.     

Gas-liquid chromatography and liquid chromatography of ethylenethiourea in fresh vegetable crops, fruits, milk, and cooked foods

The Onley-Yip procedure for determining ethylenethiourea (ETU) in milk and crops was modified to reduce interferences by the ethylenebisdithiocarbamates (EBDCs). A 20 g crop-methanol extract is cleaned up by adsorbing the sample onto Gas-Chrom S. desorbing ETU, and eluting ETU from aluminum oxide with chloroform containing ethanol. ETU is converted to the S-butyl derivative for gas-liquid chromatography (GLC) and flame photometric detection (sulfur mode). For liquid chromatography (LC), ETU is cleaned up on another aluminum oxide column and injected directly. LC and GLC results are confirmed by thin layer chromatography. A cooking procedure based on conversion of EBDCs to ETU is included for surveying crops for possible EBDC content. Recoveries from 8 crops and milk fortified at 0.05 ppm ETU ranged from 73 to 100%.     

Residues of the lampricides 3-trifluoromethyl-4-nitrophenol and niclosamide in muscle tissue of rainbow trout

Rainbow trout (Oncorhyncus mykiss) were exposed to the (14)C-labeled lampricide 3-trifluoromethyl-4-nitrophenol (TFM) (2.1 mg/L) or niclosamide (0.055 mg/L) in an aerated static water bath for 24 h. Fish were sacrificed immediately after exposure. Subsamples of skin-on muscle tissue were analyzed for residues of the lampricides. The primary residues in muscle tissue from fish exposed to TFM were parent TFM (1.08 +/- 0.82 nmol/g) and TFM-glucuronide (0.44 +/- 0.24 nmol/g). Muscle tissue from fish exposed to niclosamide contained niclosamide (1.42 +/- 0.51 nmol/g), niclosamide-glucuronide (0.0644 +/- 0.0276 nmol/g), and a metabolite not previously reported, niclosamide sulfate ester (1.12 +/- 0.33 nmol/g).