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1.
A method is presented for determination of residues of gentian violet (GV), its demethylated metabolites (pentamethyl and tetramethyl), and leucogentian violet (LGV) in chicken tissue. The analytes are extracted from tissue with acetonitrile/buffer and partitioned into methylene chloride. Polar lipids are removed on an alumina column followed by partitioning into methylene chloride from a citrate buffer. The compounds of interest are isolated on a disposable carboxylic acid cation exchange column and then eluted with 0.02% HCl in methanol. GV, its metabolites, and LGV are determined by liquid chromatography using isocratic elution with a buffered mobile phase from a cyano column and amperometric electrochemical detection at +1.000 V. Average recoveries of GV and LGV from commercially purchased chicken liver fortified with 20 ppb of each compound were 92% [standard deviation (SD) = 7, coefficient of variation (CV) = 7.6%] and 86% (SD = 7, CV = 8.1%), respectively. Average recoveries of GV, LGV, the pentamethyl metabolite, and 1 of the tetramethyl metabolites from control chicken liver (provided by the Center for Veterinary Medicine) fortified with 20 ppb of each compound were 80% (SD = 7, CV = 8.8%), 76% (SD = 3, CV = 3.9%), 83% (SD = 6, CV = 7.2%), and 76% (SD = 8, CV = 10.5%), respectively. Mean results from 10 analyses of residue-incurred chicken liver were 31 ppb GV (SD = 3, CV = 9.7%), 34 ppb pentamethyl metabolite (SD = 3, CV = 8.8%), and 40 ppb tetramethyl metabolite(s) (SD = 2, CV = 5.0%), for an average value of 105 ppb total residues (SD = 6, CV = 5.7%); no LGV was found. Data are also presented to show applicability of the method to muscle tissue.  相似文献   

2.
A screening method has been developed for determining organophosphorus pesticides at ng/L levels in drinking water. Sixteen organophosphorus pesticides, diazinon, diazinon-oxon, dimethoate, ronnel, beta-phosphamidon, methyl parathion, ethyl parathion, malathion, chlorpyrifos, fenitrothion, ruelene, methidathion, ethion, EPN, phosalone, and phosmet, were extracted by Amberlite XAD-2 resin from 100 and 200 L drinking water previously spiked with these pesticides. The pesticides were eluted from the XAD-2 resin with acetone-hexane (15+85). The concentrated extract was analyzed by gas chromatography using a nitrogen-phosphorus selective detector and by gas chromatography-mass spectrometry using selected ion monitoring. Recoveries at the 10 and 100 ng/L spiking levels were greater than 90%, except recoveries for dimethoate and phosphamidon were 37 and 42%, respectively. The analysis of 300 L Ottawa tap water showed no detectable amounts (less than 1 ng/L) of any of the 16 organophosphorus pesticides.  相似文献   

3.
A rapid LC-MS/MS method, using a triple-quadrupole/linear ion trap mass spectrometer, was developed for the quantitative determination of oleandrin in serum, urine, and tissue samples. Oleandrin, the major cardiac glycoside of oleander (Nerium oleander L.), was extracted from serum and urine samples with methylene chloride and from tissues with acetonitrile. The tissue extracts were cleaned up using Florisil solid-phase extraction columns. Six replicate fortifications of serum and urine at 0.001 microg/g (1 ppb) oleandrin gave average recoveries of 97% with 5% CV (relative standard deviation) and 107% with 7% CV, respectively. Six replicate fortifications of liver at 0.005 microg/g (5 ppb) oleandrin gave average recoveries of 98% with 6% CV. This is the first report of a positive mass spectrometric identification and quantitation of oleandrin in tissue samples from oleander intoxication cases. The sensitivity and specificity of the LC-MS/MS analysis enables it to be the method of choice for toxicological investigations of oleander poisoning.  相似文献   

4.
A gas chromatographic (GC) method is described to determine deoxynivalenol in wheat and corn at levels as low as 20 ppb. Ground samples are extracted with water, adsorbed onto a Clin Elut column, extracted with ethyl acetate, and passed through a silica gel Sep-Pak cartridge. The final extract is then derivatized with N-heptafluorobutyrylimidazole and quantitated by GC using an electron capture detector. Recoveries are greater than 85% for spiked samples at levels of 50-1000 ppb. Results for wheat, corn, and mixed feed samples are given as well as the results of an interlaboratory study on a naturally contaminated wheat sample.  相似文献   

5.
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.  相似文献   

6.
A liquid chromatographic procedure for the determination of albendazole ([5-(propylthio)-1H-benzimidazol-2yl]carbamic acid methyl ester) and its major metabolites, albendazole sulfoxide, albendazole sulfone, and albendazole-2- aminosulfone in rainbow trout, tilapia, and salmon muscle with adhering skin tissue is described. The muscle tissue samples are made alkaline with potassium carbonate and extracted with ethyl acetate. The extracts are further subjected to cleanup by utilizing a number of liquid-liquid extraction steps. After solvent evaporation, the residue is reconstituted in mobile phase and chromatographed. The chromatography is carried out on a reversed phase Luna C(18) column, using acetonitrile/methanol/buffer as a mobile phase and a fluorescence detector. The average recoveries from the fortified muscle tissue of the three fish species for albendazole (25-100 ppb), albendazole sulfoxide (15.5-62 ppb), albendazole sulfone (1-10 ppb), and albendazole-2- aminosulfone (10-100 ppb) were 94, 77, 82, and 67%, respectively. The average CV for each compound was < or =10%. The procedure was validated and then applied to the determination of albendazole and its three major metabolites in the muscle tissue of the three fish species obtained after orally dosing with albendazole.  相似文献   

7.
Ten laboratories participated in a collaborative study of a method for the determination of N-nitrosodimethylamine (NDMA) in nonfat dry milk. NDMA is eluted with dichloromethane from a mixture of Celite, acidic sulfamic acid, and nonfat dry milk (all packed in a chromatography column), concentrated in a Kuderna -Danish concentrator, and finally analyzed by a GC-thermal energy analyzer technique. Ten samples were studied: 6 were naturally contaminated (NDMA levels 0.38-3.56 ppb) and 4 were spiked with known levels (0.96 and 3.2 ppb) of NDMA. The coefficients of variation (CV) of the complete data for the naturally contaminated samples (excluding the 2 samples containing the lowest levels) were 8.5% and 22.5% for repeatability and reproducibility, respectively. The corresponding CVs for the spiked samples were 14.4% and 20.4%, respectively. The percent recoveries of the added NDMA in the spiked samples (at the 2 levels indicated above) were 101.6 +/- 3.2 (omitting 1 outlier) and 95 +/- 2.1, respectively. The method has been adopted official first action.  相似文献   

8.
A multiresidue method was developed for the simultaneous determination of low parts per billion (ppb) concentrations of the herbicides alachlor, metolachlor, atrazine, and simazine in water and soil using isotope dilution gas chromatography/mass spectrometry (GC/MS). Known amounts of 15N,13C-alachlor and 2H5-atrazine were added to each sample as internal standards. The samples were then prepared by a solid phase extraction with no further cleanup. A high resolution GC/low resolution MS system with data acquisition in selected ion monitoring mode was used to quantitate herbicides in the extract. The limit of detection was 0.05 ppb for water and 0.5 ppb for soil. Accuracy greater than 80% and precision better than 4% was demonstrated with spiked samples.  相似文献   

9.
A sensitive method is described for determining dicamba at low micrograms/L levels in ground waters by capillary column gas chromatography with electron-capture detection (GC-EC); compound identity is confirmed by gas chromatography-mass spectrometry (GC-MS) using selected ion monitoring. Dicamba residue is hydrolyzed in KOH to form the potassium salt. The sample is then extracted with ethyl ether which is discarded. The aqueous phase is acidified to pH less than 1 and extracted twice with ethyl ether. The combined ethyl ether extracts are concentrated, and the residue is methylated using diazomethane to form the corresponding dicamba ester. The derivatized sample is cleaned up on a deactivated silica gel column. The methylated dicamba is separated on an SE-30 capillary column and quantitated by electron-capture or mass spectrometric detection. Average recoveries (X +/- SD) for ground water samples fortified with 0.40 microgram/L of dicamba are 86 +/- 5% by GC-EC and 97 +/- 7% by GC-MS detections. The EDL (estimated detection limit) for this method is 0.1 microgram dicamba/L water (ppb).  相似文献   

10.
A technique has been developed to extract soil phenolics by their adsorption onto resin, the separation of resin from soil, and desorption from the resin followed by high performance liquid chromatography (HPLC) analysis. Four representative phenolic acids, p-hydroxybenzoic, p-hydroxycinnamic, p-methoxybenzoic and 2,4-dimethoxybenzoic acids, were added to a subtropical soil (66 nmol g?1 soil) and recovered by extraction with Amberlite XAD-4 resin. The recovery efficiency of the added phenolics was greater using a flotation method to separate resin from soil than by a filtration method. The recoveries of p-hydroxybenzoic acid and p-hydroxycinnamic acid decreased with increasing extractant pH. Recoveries of p-methoxybenzoic acid and 2,4-dimethoxybenzoic acid increased slightly with increasing pH. The addition of NaCl to the XAD-4 resin extractant generally increased the recovery of phenolics by filtration but not by flotation. The recoveries of phenolics from the soil by extraction with XAD-4 resin were much greater than by alkaline extraction at pH 11.  相似文献   

11.
An accurate, sensitive method is described for the determination of monensin residue in chicken tissues by liquid chromatography (LC), in which monensin is derivatized with a fluorescent labeling reagent, 9-anthryldiazomethane (ADAM), to enable fluorometric detection. Samples are extracted with methanol-water (8 + 2), the extract is partitioned between CHCl3 and water, and the CHCl3 layer is cleaned up by silica gel column chromatography. Free monensin, obtained by treatment with phosphate buffer solution (pH 3) at 0 degrees C, is derivatized with ADAM and passed through a disposable silica cartridge. Monensin-ADAM is identified and quantitated by normal phase LC using fluorometric detection. The detection limit is 1 ppb in chicken tissues. Recoveries were 77.6 +/- 1.8% at 1 ppm, 56.7 +/- 7.1% at 100 ppb, and 46.5 +/- 3.7% at 10 ppb fortification levels in chicken. Gas chromatography-mass spectrometry is capable of confirming monensin methyl ester tris trimethylsilyl ether in samples containing residues greater than 5 ppm.  相似文献   

12.
A method is described for determination of tricyclazole residues in soil and water. Tricyclazole is extracted from soil by refluxing with ethyl acetate-acetone (80 + 20 v/v) and from water by partitioning into dichloromethane. The soil extract is purified by coagulation. The compound is detected and measured by gas chromatography using a flame photometer operated in the sulfur mode. Detection limits are 8 ppb for soil and 0.8 ppb for water. Recoveries for control samples fortified with tricyclazole at 0.1-5.0 ppm averaged 97.1% for soil and 108.1% for water.  相似文献   

13.
Anthocyanins and their related compounds were extracted from grape skins of Pinot noir, using 50% aqueous methanol, and purified by solid phase extraction chromatography using XAD-7 resin to obtain a pigment-rich fraction. This fraction was subjected to multilayer coil countercurrent chromatography (MLCCC) using a quaternary solvent system consisting of tert-butyl methyl ether/n-butanol/acetonitrile/water acidified with 0.01% trifluoroacetic acid (2:2:0.1-1.8:5) (v/v/v/v) in a step gradient elution to separate anthocyanin oligomers from grape anthocyanins. In the process of the characterization of the MLCCC fractions by electrospray mass spectrometry, two noncolored anthocyanin derivatives were found and characterized on the basis of their mass spectral data. As a result, these compounds have been tentatively identified as coupling products between both hydrated malvidin-3-glucoside and peonidin-3-glucoside, with 2-S-glutathionyl caffeoyl tartaric acid (GRP). It is therefore proposed that grape skins contain this new class of coupling product, and a possible chemical pathway for their formation is suggested.  相似文献   

14.
A method is described for determining volatile nitrosamines in baby bottle rubber nipples and pacifiers. The method consists of overnight soaking of the sample with dichloromethane in the presence of propyl gallate, an inhibitor for artifactual formation of nitrosamines; extraction with dichloromethane using an ambient temperature column procedure; distillation from aqueous alkali; extraction of the aqueous distillate with dichloromethane and concentration of the extract using a Kuderna-Danish concentrator; and final analysis by gas chromatography with detection by thermal energy analyzer. Major improvements over other published methods include a simpler extraction, a more efficient distillation and concentration to minimize losses, and incorporation of propyl gallate inhibitor as well as of a test to detect unsuitable dichloromethane solvent that otherwise might lead to artifactual formation. The method is highly accurate (approximately 90% recovery) and precise (av. CV = 4.7% at greater than 9 ppb levels) and is applicable to determination of nitrosamines in both rubber- and plastic-based products.  相似文献   

15.
There is no data currently available on acidic pesticides in the drinking water of Greece, although considerable quantities of them are in use. In this study, the occurrence of the six most important acidic herbicides in the drinking water of Greece was investigated. The target compounds studied include four chlorophenoxy herbicides, namely mecoprop, dichlorprop, MCPA and 2,4-D, and two other acidic herbicides, i.e. bromoxynil and bentazone. Analysis was carried out at a concentration level of 100 ng L?1 using capillary gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM). The method involved a pre-concentration with solid phase extraction and derivatization with pentafluorobenzyl bromide. Thirty-eight samples of drinking water from nine regions in Greece were screened. No herbicides were detected although fortification experiments with parallel water samples resulted in recovery rates better than 70%. The detection limits of the recovered compounds were found to be between 10 and 50 ng L?1.  相似文献   

16.
High-performance liquid chromatography (HPLC) methods for the determination of phenyl urea herbicides in water are described. The target compounds include chlortoluron, diuron, fluometuron, isoproturon, linuron, metobromuron, metoxuron, monuron, neburon, and siduron. Water was subjected to solid phase extraction (SPE) using either automated SPE with 47 mm C(18) Empore disks or on-line precolumn concentration. Herbicides were separated on a C(18) reversed phase column with an acetonitile-water gradient and were detected with either a diode array detector (DAD) or a postcolumn photolysis and derivatization (PPD) detector system. Photolysis converted the phenyl ureas to monoalkylamines that were derivatized to fluorescent isoindoles by reaction with o-phthalaldehyde and 2-mercaptoethanol. The DAD monitoring at 245 nm was linear over three decades with instrument detection limits of approximately 0.01 mg/L. SPE efficiency was between 48 and 70% in laboratory reagent water, but use of the internal standard quantitation method improved accuracy. High total dissolved solids and total organic carbon values in surface water improved recoveries relative to laboratory reagent water for all of the phenyl ureas. In Colorado River water spiked at 1 or 50 microg/L, mean recoveries ranged from 74 to 104%. Method detection limits (MDLs) ranged from 4 to 40 ng/L (parts per trillion) with the DAD instrument. PPD detection was highly specific but resulted in a slight loss in chromatographic efficiency and average MDLs approximately 5 times higher using a single set of detection conditions. The study indicates that methods based on SPE followed by HPLC with diode array or PPD detection have practical utility for trace analysis of phenyl ureas in drinking water or surface waters.  相似文献   

17.
Atomic Fluorescence-based methods have been developed for measuring ultratrace levels of mercury (Hg) in environmental (water, soil) and biological (fish tissue) samples. In addition, methods for preparation of water, soil, and tissue samples have been developed. For the analysis of total Hg in soil, sediment and fish the samples are digested with concentrated nitric acid in sealed glass ampules, and subsequently autoclaved. Water samples are digested using standard brominating procedures. A Merlin Plus, PS Analytical atomic fluorescence spectrometer (AFS) system equipped with an autosampler, vapor generator, fluorescence detector and a PC based integrator package is used in the determination of total Hg. The determination of Hg mercury species in water, without pre-derivatization, involves adsorbent pre-concentration of the organomercurials onto sulfydryl-cotton fibers. The organic Hg compounds are eluted with a small volume of acidic KBr and CuSO4 and extracted into dichloromethane. Sediment, soil and tissue samples are homogenized and the organomercurials first released from the sample by the combined action of acidic KBr and CuSO4 and extracted into dichloromethane. The initial extracts are subjected to thiosulfate clean-up and the organomercury species are isolated as their chloride derivatives by cupric chloride addition and subsequent extraction into a small volume of dichloromethane. Analysis of organic Hg compounds is accomplished by capillary column chromatography coupled with atomic fluorescence detection.  相似文献   

18.
Pet and food animal (hogs, chicken, and fish) feeds were recently found to be contaminated with melamine (MEL). A quantitative and confirmatory method is presented to determine MEL residues in edible tissues from fish fed this contaminant. Edible tissues were extracted with acidic acetonitrile, defatted with dichloromethane, and cleaned up using mixed-mode cation exchange solid-phase extraction cartridges. Extracts were analyzed by liquid chromatography with tandem mass spectrometry with hydrophilic interaction chromatography and electrospray ionization in positive ion mode. Fish and shrimp tissues were fortified with 10-500 microg/kg (ppb) of MEL with an average recovery of 63.8% (21.5% relative standard deviation, n = 121). Incurred fish tissues were generated by feeding fish up to 400 mg/kg of MEL or a combination of MEL and the related triazine cyanuric acid (CYA). MEL and CYA are known to form an insoluble complex in the kidneys, which may lead to renal failure. Fifty-five treated catfish, trout, tilapia, and salmon were analyzed after withdrawal times of 1-14 days. MEL residues were found in edible tissues from all of the fish with concentrations ranging from 0.011 to 210 mg/kg (ppm). Incurred shrimp and a survey of market seafood products were also analyzed as part of this study.  相似文献   

19.
Liquid chromatographic methods are presented for the quantitative and confirmatory determination of malachite green (MG) and leucomalachite green (LMG) for channel catfish, rainbow trout, tilapia, basa, Atlantic salmon, and tiger shrimp. Residues were extracted from tissues with ammonium acetate buffer and acetonitrile and isolated by partitioning into dichloromethane. LMG was quantitatively oxidized to the chromic MG with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. Extracts were analyzed for total MG by liquid chromatography with both visible detection (LC-VIS) at 618 nm for routine screening and ion trap mass spectrometry (LC-MSn) with no discharge-atmospheric pressure chemical ionization for residue confirmation. The method was validated in each species fortified with LMG at 1, 2, 4, and 10 ng/g (ppb), and average recoveries ranged from 85.9 to 93.9%. Quantitative data were consistent for the two detection methods, with measured method detection limits of 1.0 ng/g for LC-VIS and 0.25 ng/g for LC-MSn. Incurred tissues from catfish, trout, tilapia, and salmon that had been treated with MG were also extracted and analyzed as part of this study.  相似文献   

20.
Gas chromatography olfactometry (GCO) was used to determine key aroma compounds of two red wine vinegars. Sensory analysis was performed to choose the best neutralization agent of acetic acid (NaOH or MgO) and to test representativeness of four extracts obtained by different methods (dichloromethane extraction, XAD-2, mixture of XAD-2 and XAD-7, and Extrelut resins extraction). Neutralization with NaOH followed by dichloromethane extraction was selected to extract volatile compounds of vinegars. Key odorant compounds were determined by GCO based on detection frequency with 13 people. In the two red wine vinegars, 13 odors were perceived by at least 70% of the panelists, and 8 compounds among the 13 were identified: acetic acid, 3-methylbutyric acid, 2-phenyl-1-ethanol, 2, 3-butanedione, butyric acid, 2-methylbutyric acid, mixture of 2- and 3-methyl-1-butanol, and two newly identified compounds in vinegar, 3-hydroxy-2-pentanone and 3-(methylthio)-1-propanal. Quantification of all the volatile compounds was performed by GC-FID, and 10 other compounds were identified for the first time in wine vinegar.  相似文献   

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