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1.
Chemosphere ; 256: 127023, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32428742

RESUMO

Persistent organic pollutants (POPs) methods for foods and animal feeds require sufficient sample intake followed by an extensive removal of interfering matrix components and concentration before a gas chromatographic mass spectrometry (GC-MS) method can be applied. The extraction dissolves associated lipids in animal foods or feeds. Methods must eliminate all co-extracted lipids before determination by GC-MS. A new approach for removing lipids is presented using basic silica gel or metal ion immobilized silica gel (Ag+) in a single step. Absorbent order, adsorbent amounts, and flow rates were found to be essential for consistent results. KOH/silica gel or Ag+ ion (AgNO3) silica gel were both shown to retain 75-85% of the co-extracted lipids without using sulfuric acid. KOH/silica gel method applied to butter fortified at 7.3 pg TEQ/g lipid with polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) produced accurate results for all fortified congeners with 20% of predicted (n = 6). Ag+ silica gel incorporated into the Miura GO-EHT automated system produced similar results fortified at 3 pg TEQ/g lipid. During PCDD/F fortifications of butter with PCDD/Fs (n = 6), labeled standard recoveries for PCDD/Fs and planar polychlorinated biphenyls (PCBs) were all acceptable (52-99%) averaging 77% using the Miura system. A reduction in the amounts of sulfuric acid silica gel needed was possible in the completion of co-extractant removal. PCDD/F spikes into butter and for a spiked sunflower oil (PCDD/Fs and coplanar PCBs) were within ± 20% of the predicted using the Miura system; suitable for current methods criteria for foods including criteria in EU legislation.


Assuntos
Poluentes Ambientais/análise , Contaminação de Alimentos/análise , Animais , Benzofuranos/análise , Manteiga/análise , Dibenzofuranos/análise , Dibenzofuranos Policlorados/análise , Cromatografia Gasosa-Espectrometria de Massas , Lipídeos/análise , Espectrometria de Massas , Bifenilos Policlorados/análise , Dibenzodioxinas Policloradas/análise
2.
J Agric Food Chem ; 66(44): 11823-11829, 2018 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-30350972

RESUMO

A quadrupole/orbital trapping mass spectrometer or Q-Exactive (QE) interfaced with a gas chromatograph (GC) was optimized for measuring polychlorinated dibenzo- p-dioxins, dibenzofurans (PCDD/Fs), and polychlorinated biphenyls (PCBs) in foods. Figures of merit include (1) an instrument detection limit (IDL) for 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) of 9 femtograms (fg), (2) quantitative mass resolution from PCDD interferences (e.g., PCBs, methoxy-PCBs DDTs, polychlorodibenzylphenyl ethers, polychloroxanthenes, methyl-polychlorodibenzofuran, and polychlorodibenzothiophenes), and (3) mass accuracy <1 ppm at the IDL. The QE measured the concentrations of PCDD/Fs and PCBs in whole cow's milk with no known source of contamination (e.g., TCDD 33 fg/g fat). A National Institute of Standards and Technology (NIST) unfortified human milk standard reference material (SRM) 1953 was measured determining 27 PCDD/F and PCB congeners with an average difference of 7.6% from the certified results. The QE-GC is a benchtop instrument, easy to service, easy to operate, and requires no lock masses, mass preselection, or chemical ionization conditions. The QE-GC demonstrated that it can be an alternative to the double focusing magnetic sector instruments (sector) for the high-resolution measurement of PCDD/Fs and PCBs in dairy products.


Assuntos
Cromatografia Gasosa/métodos , Contaminação de Alimentos/análise , Espectrometria de Massas/métodos , Leite Humano/química , Leite/química , Animais , Benzofuranos/análise , Bovinos , Dioxinas/análise , Humanos , Bifenilos Policlorados/análise , Dibenzodioxinas Policloradas/análise , Polímeros/análise
3.
J Agric Food Chem ; 66(37): 9573-9581, 2018 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-30169025

RESUMO

This perspective discusses the use of liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) for multiresidue analysis of pesticides in foods and agricultural commodities. HRMS has the important distinction and advantage of mass-resolving power and, therefore, requires different concepts, experiments, and guidance for screening, identification, and quantitation of pesticides in complex food matrices over triple quadrupole mass spectrometry. HRMS approaches for pesticide screening, including full-scan experiments in conjunction with tandem mass spectrometry (MS/MS) experiments, are described. This approach results in the generation of chromatographic retention times and high-resolution mass spectra with accurate mass measurements that can be used to create compound databases. New data processing tools can create an efficient and optimized screening approach that can speed the analysis and identification of compounds, reduce the need for chemical standards, and harmonize pesticide analytical procedures.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Contaminação de Alimentos/análise , Espectrometria de Massas em Tandem/métodos , Cromatografia Líquida , Resíduos de Praguicidas , Espectrometria de Massas em Tandem/instrumentação
4.
J Agric Food Chem ; 64(31): 6125-32, 2016 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-27101866

RESUMO

A simplified sample preparation method in combination with gas chromatography-triple-quadrupole mass spectrometry (GC-MS/MS) analysis was developed and validated for the simultaneous determination of 227 pesticides in green tea, ginseng, gingko leaves, saw palmetto, spearmint, and black pepper samples. The botanical samples were hydrated with water and extracted with acetonitrile, magnesium sulfate, and sodium chloride. The acetonitrile extract was cleaned up using solid phase extraction with carbon-coated alumina/primary-secondary amine with or without C18. Recovery studies using matrix blanks fortified with pesticides at concentrations of 10, 25, 100, and 500 µg/kg resulted in average recoveries of 70-99% and relative standard deviation of 5-13% for all tested botanicals except for black pepper, for which lower recoveries of fortified pesticides were observed. Matrix-matched standard calibration curves revealed good linearity (r(2) > 0.99) across a wide concentration range (1-1000 µg/L). Nine commercially available tea and 23 ginseng samples were analyzed using this method. Results revealed 36 pesticides were detected in the 9 tea samples at concentrations of 2-3500 µg/kg and 61 pesticides were detected in the 23 ginseng samples at concentrations of 1-12500 µg/kg.


Assuntos
Suplementos Nutricionais/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Preparações de Plantas/análise , Contaminação de Medicamentos , Ginkgo biloba/química , Panax/química , Resíduos de Praguicidas/isolamento & purificação , Piper nigrum/química , Extratos Vegetais/química , Serenoa , Extração em Fase Sólida
6.
J Agric Food Chem ; 63(37): 8116-24, 2015 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-26209005

RESUMO

Black, green, white, and Oolong teas, all derived from leaves of Camellia sinensis, are widely consumed throughout the world and represent a significant part of the beverages consumed by Americans. A gas chromatography-triple quadrupole-based method, previously validated for pesticides on dried botanical dietary supplements, including green tea, was used to measure pesticides fortified into black and green teas at 10, 25, 100, and 500 µg/kg. Teas from 18 vendors of tea products were then surveyed for pesticides. Of 62 black, green, white, and Oolong tea products, 31 (50%) had residues of pesticides for which no United States Environmental Protection Agency tolerances are established for tea. The following pesticides were identified on tea leaves, with concentrations between 1 and 3200 µg/kg: anthraquinone, azoxystrobin, bifenthrin, buprofesin, chlorpyrifos, cyhalothrin, cypermethrin, DDE-p,p', DDT-o,p, DDT-p,p', deltamethrin, endosulfan, fenvalerate, heptachlor, hexachlorocyclohexanes (α,ß,γ,δ), phenylphenol, pyridaben, tebuconazole, tebufenpyrad, and triazophos. DDT-p,p' was found at much higher concentrations than DDE-p,p' or DDT-o,p' in 9 of 10 teas with DDTs. A comparison between three commercially available solid-phase extraction (SPE) column brands of the same type revealed that two brands of SPE columns could be interchanged without modification of the tea method.


Assuntos
Camellia sinensis/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Folhas de Planta/química , Chá/química , Praguicidas/análise , Extratos Vegetais/química , Estados Unidos , United States Environmental Protection Agency
7.
J Agric Food Chem ; 63(37): 8314-32, 2015 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-25531669

RESUMO

Ultrahigh-performance liquid chromatography using positive electrospray ionization and quadrupole orbital ion trap high-resolution mass spectrometry was evaluated for analyzing mycotoxins in finished cereal and nut products. Optimizing the orbital ion trap mass analyzer in full-scan mode using mycotoxin-fortified matrix extracts gave mass accuracies, δM, of < ± 2.0 ppm at 70,000 full width at half maximum (FWHM) mass resolution (RFWHM). The limits of quantitation were matrix- and mycotoxin-dependent, ranging from 0.02 to 11.6 µg/kg. Mean recoveries and standard deviations for mycotoxins from acetonitrile/water extraction at their relevant fortification levels were 91 ± 10, 94 ± 10, 98 ± 12, 91 ± 13, 99 ± 15, and 93 ± 17% for corn, rice, wheat, almond, peanut, and pistachio, respectively. Nineteen mycotoxins with concentrations ranging from 0.3 (aflatoxin B1 in peanut and almond) to 1175 µg/kg (fumonisin B1 in corn flour) were found in 35 of the 70 commercial grain and nut samples surveyed. Mycotoxins could be identified at δM < ± 5 ppm by identifying the precursor and product ions in full-scan MS and data-dependent MS/MS modes. This method demonstrates a new analytical approach for monitoring mycotoxins in finished grain and nut products.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Grão Comestível/química , Contaminação de Alimentos/análise , Micotoxinas/análise , Nozes/química , Espectrometria de Massas por Ionização por Electrospray/métodos , Aflatoxinas/análise , Arachis/química , Alcaloides de Claviceps/análise , Fumonisinas/análise , Ocratoxinas/análise , Prunus dulcis/química , Tricotecenos/análise
8.
J Agric Food Chem ; 61(26): 6265-73, 2013 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-23746324

RESUMO

A stable isotope dilution assay and liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of 12 mycotoxins, aflatoxins B1, B2, G1, G2, and M1, deoxynivalenol, fumonisins B1, B2, and B3, ochratoxin A, T-2 toxin, and zearalenone, in milk-based infant formula and foods. Samples were fortified with 12 ¹³C uniformly labeled mycotoxins ([¹³C]-mycotoxins) that correspond to the 12 target mycotoxins and prepared by dilution and filtration, followed by LC-MS/MS analysis. Quantitation was achieved using the relative response factors of [¹³C]-mycotoxins and target mycotoxins. The average recoveries in fortified milk, milk-based infant formula, milk powder, and baby yogurt of aflatoxins B1, B2, G1, and G2 (2, 10, and 50 µg/kg), aflatoxin M1 (0.5, 2.5, and 12.5 µg/kg), deoxynivalenol, fumonisins B1, B2, and B3 (40, 200, and 1000 µg/kg), ochratoxin A, T-2 toxin, and zearalenone (20, 100, and 500 µg/kg), range from 89 to 126% with RSDs of <20%. The individual recoveries in the four fortified matrices range from 72% (fumonisin B3, 20 µg/kg, milk-based infant formula) to 136% (T-2 toxin, 20 µg/kg, milk powder), with RSDs ranging from 2 to 25%. The limits of quantitation (LOQs) were from 0.01 µg/kg (aflatoxin M1) to 2 (fumonisin B1) µg/kg. Aflatoxin M1 was detected in two European Reference materials at 0.127 ± 0.013 µg/kg (certified value = 0.111 ± 0.018 µg/kg) and 0.46 ± 0.04 µg/kg (certified value = 0.44 ± 0.06 µg/kg), respectively. In 60 local market samples, aflatoxins B1 (1.14 ± 0.10 µg/kg) and B2 (0.20 ± 0.03 µg/kg) were detected in one milk powder sample. Aflatoxin M1 was detected in three imported samples (condensed milk, milk-based infant formula, and table cream), ranging from 0.10 to 0.40 µg/kg. The validated method provides sufficient selectivity, sensitivity, accuracy, and reproducibility to screen for aflatoxin M1 at nanograms per kilogram concentrations and other mycotoxins, without using standard addition or matrix-matched calibration to compensate for matrix effects.


Assuntos
Laticínios/análise , Contaminação de Alimentos , Inspeção de Alimentos/métodos , Fórmulas Infantis/química , Micotoxinas/análise , Adulto , Criança , Humanos , Lactente , Micotoxinas/química
9.
J Agric Food Chem ; 61(20): 4771-82, 2013 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-23614683

RESUMO

Mycotoxins in foods have long been recognized as potential health hazards due to their toxic and carcinogenic properties. A simple and rapid method was developed to detect 26 mycotoxins (aflatoxins, ochratoxins, fumonisins, trichothecenes, and ergot alkaloids) in corn, rice, wheat, almond, peanut, and pistachio products using high-performance liquid chromatography-triple-quadrupole mass spectrometry. Test portions of homogenized grain or nut products were extracted with acetonitrile/water (85:15, v/v), followed by high-speed centrifugation and dilution with water. Mean recoveries (± standard deviations) were 84 ± 6, 89 ± 6, 97 ± 9, 87 ± 12, 104 ± 16, and 92 ± 18% from corn, rice, wheat, almond, peanut, and pistachio products, respectively, and the matrix-dependent instrument quantitation limits ranged from 0.2 to 12.8 µg/kg, depending on the mycotoxin. Matrix effects, as measured by the slope ratios of matrix-matched and solvent-only calibration curves, revealed primarily suppression and were more pronounced in nuts than in grains. The measured mycotoxin concentrations in 11 corn and wheat reference materials were not different from the certified concentrations. Nineteen mycotoxins were identified and measured in 35 of 70 commercial grain and nut products, ranging from 0.3 ± 0.1 µg/kg (aflatoxin B1 in peanuts) to 1143 ± 87 µg/kg (fumonisin B1 in corn flour). This rapid and efficient method was shown to be rugged and effective for the multiresidue analysis of mycotoxins in finished grain and nut products.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Grão Comestível/química , Contaminação de Alimentos/análise , Espectrometria de Massas/métodos , Micotoxinas/análise , Nozes/química , Análise de Alimentos/métodos
10.
Anal Chem ; 85(9): 4686-93, 2013 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-23534560

RESUMO

Dietary supplements form an increasing part of the American diet, yet broadly applicable multiresidue pesticide methods have not been evaluated for many of these supplements. A method for the analysis of 310 pesticides, isomers, and pesticide metabolites in dried botanical dietary supplements has been developed and validated. Sample preparation involved acetonitrile:water added to the botanical along with anhydrous magnesium sulfate and sodium chloride for extraction, followed by cleanup with solid-phase extraction using a tandem cartridge consisting of graphitized carbon black (GCB) and primary-secondary amine sorbent (PSA). Pesticides were measured by gas chromatography-tandem mass spectrometry. Accuracy and precision were evaluated through fortifications of 24 botanicals at 10, 25, 100, and 500 µg/kg. Mean pesticide recoveries and relative standard deviations (RSDs) for all botanicals were 97%, 91%, 90%, and 90% and 15%, 10%, 8%, and 6% at 10, 25, 100, and 500 µg/kg, respectively. The method was applied to 21 incurred botanicals. Quinoxyfen was measured in hops (100-620 µg/kg). Tetraconazole (48 µg/kg), tetramethrin (15 µg/kg), methamidophos (50 µg/kg), and chlorpyrifos (93 µg/kg) were measured in licorice, mallow, tea, and tribulus, respectively. Quintozene, its metabolites and contaminants (pentachloroaniline, pentachlorobenzene, pentachloroanisole, and pentachlorothioanisole and hexachlorobenzene and tecnazene, respectively), with hexachlorocyclohexanes and DDT were identified in ginseng sources along with azoxystrobin, diazinon, and dimethomorph between 0.7 and 2800 µg/kg. Validation with these botanicals demonstrated the extent of this method's applicability for screening 310 pesticides in a wide array of botanical dietary supplements.


Assuntos
Acetonitrilas/isolamento & purificação , Suplementos Nutricionais/análise , Resíduos de Praguicidas/análise , Extração em Fase Sólida , Cromatografia Gasosa-Espectrometria de Massas , Estrutura Molecular
11.
J Agric Food Chem ; 60(40): 9991-9, 2012 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-22931171

RESUMO

An automated dispersive solid phase extraction (dSPE) cleanup procedure as part of the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method, coupled with liquid chromatography-tandem mass spectrometry using electrospray ionization in positive mode, was used for the simultaneous analysis of 236 pesticides in three dried powdered botanical dietary supplements (ginseng, saw palmetto, and gingko biloba). The procedure involved extraction of the dried powdered botanical samples with salt-out acetonitrile/water extraction using anhydrous magnesium sulfate and sodium chloride, followed by an automated dSPE cleanup using a mixture of octadodecyl- (C18) and primary-secondary amine (PSA)-linked silica sorbents and anhydrous MgSO4 and online LC-MS/MS analysis. Dynamic multiple-reaction monitoring (DMRM) based on the collection of two precursor-to-product ion transitions with their retention time windows was used for all of the targeted pesticides and the internal standard. Matrix-matched calibration standards were used for quantitation, and standard calibration curves showed linearity (r(2) > 0.99) across a concentration range of 0.2-400 ng/mL for the majority of the 236 pesticides evaluated in the three botanical matrices. Mean recoveries (average %RSD, n = 4) were 91 (6), 93 (4), 96 (3), and 99 (3)% for ginseng, 101 (9), 98 (6), 99 (4), and 102 (3)% for gingko biloba, and 100 (9), 98 (6), 96 (4), and 96 (3)% for saw palmetto at fortification concentrations of 25, 100, 250, and 500 µg/kg, respectively. The geometric mean matrix-dependent instrument detection limits were 0.17, 0.09, and 0.14 µg/kg on the basis of the studies of 236 pesticides tested in ginseng roots, gingko biloba leaves, and saw palmetto berries, respectively. The method was used to analyze incurred ginseng samples that contained thermally labile pesticides with a concentration range of 2-200 µg/kg, indicating different classes of pesticides are being applied to these botanicals other than the traditional pesticides that are commonly used and analyzed by gas chromatography techniques. The method demonstrates the use of an automated cleanup procedure and the LC-MS/MS detection of multiple pesticide residues in dried, powdered botanical dietary supplements.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Suplementos Nutricionais/análise , Resíduos de Praguicidas/análise , Preparações de Plantas/química , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Ginkgo biloba/química , Panax/química , Extratos Vegetais/química , Serenoa
12.
Anal Chem ; 84(13): 5677-84, 2012 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-22686274

RESUMO

Modern determination techniques for pesticides must yield identification quickly with high confidence for timely enforcement of tolerances. A protocol for the collection of liquid chromatography (LC) electrospray ionization (ESI)-quadruple linear ion trap (Q-LIT) mass spectrometry (MS) library spectra was developed. Following the protocol, an enhanced product ion (EPI) library of 240 pesticides was developed by use of spectra collected from two laboratories. A LC-Q-LIT-MS workflow using scheduled multiple reaction monitoring (sMRM) survey scan, information-dependent acquisition (IDA) triggered collection of EPI spectra, and library search was developed and tested to identify the 240 target pesticides in one single LC-Q-LIT MS analysis. By use of LC retention time, one sMRM survey scan transition, and a library search, 75-87% of the 240 pesticides were identified in a single LC/MS analysis at fortified concentrations of 10 ng/g in 18 different foods. A conventional approach with LC-MS/MS using two MRM transitions produced the same identifications and comparable quantitative results with the same incurred foods as the LC-Q-LIT using EPI library search, finding 1.2-49 ng/g of either carbaryl, carbendazim, fenbuconazole, propiconazole, or pyridaben in peaches; carbendazim, imazalil, terbutryn, and thiabendazole in oranges; terbutryn in salmon; and azoxystrobin in ginseng. Incurred broccoli, cabbage, and kale were screened with the same EPI library using three LC-Q-LIT and a LC-quadruple time-of-flight (Q-TOF) instruments. The library search identified azoxystrobin, cyprodinil, fludioxinil, imidacloprid, metalaxyl, spinosyn A, D, and J, amd spirotetramat with each instrument. The approach has a broad application in LC-MS/MS type targeted screening in food analysis.


Assuntos
Análise de Alimentos/métodos , Praguicidas/análise , Espectrometria de Massas por Ionização por Electrospray/métodos , Espectrometria de Massas em Tandem/métodos , Cromatografia Líquida , Bases de Dados Factuais , Íons/análise
13.
Artigo em Inglês | MEDLINE | ID: mdl-22575024

RESUMO

A pressurised solvent extraction procedure coupled with a gas chromatography-mass spectrometry-selective ion monitoring (GC-MS-SIM) method was developed to determine three cyclic siloxanes, octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6) and three linear siloxanes, octamethyltrisiloxane (L3), decamethyltetrasiloxane (L4), dodecamethylpentasiloxane (L5), in silicone products. Additionally, two different extraction methods were developed to measure these siloxanes migrating into milk, infant formula and liquid simulants (50 and 95% ethanol in water). The limits of quantification (LOQs) of the six siloxanes ranged from 6 ng/g (L3) to 15 ng/g (D6). Silicone nipples and silicone bakewares were extracted using pressurised solvent extraction (PSE) and analysed using the GC-MS-SIM method. No linear siloxanes were detected in the silicone nipple samples analysed. The three cyclic siloxanes (D4, D5 and D6) were detected in all silicone nipple samples with concentrations ranging from 0.5 to 269 µg/g. In the bakeware samples, except for L3, the other five siloxanes were detected with concentrations ranging from 0.2 µg/g (L4) to 7030 µg/g (D6). To investigate the potential migration of the six siloxanes from silicone nipples to milk and infant formula, a liquid extraction and dispersive clean-up procedure was developed for the two matrices. The procedure used a mix of hexane and ethyl acetate (1 : 1, v/v) as extraction solvent and C18 powder as the dispersive clean-up sorbent. For the liquid simulants, extraction of the siloxanes was achieved using hexane without any salting out or clean-up procedures. The recoveries of the six siloxanes from the milk, infant formula and simulants fortified at 50, 100, 200, 500 and 1000 µg/l ranged from 70 to 120% with a relative standard derivation (RSD) of less than 15% (n = 4). Migration tests were performed by exposing milk, infant formula and the liquid simulants to silicone baking sheets with known concentrations of the six siloxanes at 40°C. No siloxanes were detected in milk or infant formula after 6 h of direct contact with the silicone baking sheet plaques, indicating insignificant migration of the siloxanes to milk or infant formula. Migration tests in the two simulants lasted up to 72 h and the three cyclic siloxanes were detected in 50% ethanol after an 8-h exposure and after 2 h in 95% ethanol. The highest detected concentrations of D4, D5 and D6 were 42, 36 and 155 ng/ml, respectively, indicating very limited migration of D4, D5 or D6 into the two simulants.


Assuntos
Utensílios de Alimentação e Culinária , Contaminação de Alimentos , Modelos Químicos , Elastômeros de Silicone/química , Siloxanas/análise , Animais , Alimentação com Mamadeira/instrumentação , Difusão , Contaminação de Alimentos/prevenção & controle , Embalagem de Alimentos , Cromatografia Gasosa-Espectrometria de Massas , Temperatura Alta , Humanos , Lactente , Fórmulas Infantis/química , Cinética , Limite de Detecção , Leite/química , Pressão , Reprodutibilidade dos Testes , Siloxanas/química , Solubilidade
14.
Methods Mol Biol ; 747: 131-72, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21643907

RESUMO

A multiresidue pesticide method using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) procedure and capillary gas chromatography-mass spectrometry (GC-MS) is described for the determination of 166 organochlorine, organophosphorus, and pyrethroid pesticides, metabolites, and isomers in spinach. The pesticides from spinach were extracted using acetonitrile saturated with magnesium sulfate and sodium chloride, followed by solid-phase dispersive cleanup using primary-secondary amine and graphitized carbon black sorbents and toluene. Analysis is performed using different GC-MS techniques emphasizing the benefits of non-targeted acquisition and targeted screening procedures. Non-targeted data acquisition of pesticides in the spinach was demonstrated using GC coupled to a single quadrupole mass spectrometery (GC-MS) in full scan mode or multidimensional GC-time-of-flight mass spectrometery (GC × GC-TOF/MS), along with deconvolution software and libraries. Targeted screening was achieved using GC-single quadrupole mass spectrometry in selective ion monitoring (GC-MS/SIM) mode or -tandem mass spectrometry (GC-MS/MS) in multiple reaction monitoring mode. The development of these techniques demonstrates the powerful use of GC-MS for the screening, identification, and quantitation of pesticide residues in foods.


Assuntos
Análise de Alimentos/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Praguicidas/análise
15.
J Agric Food Chem ; 59(14): 7636-46, 2011 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-21671617

RESUMO

A multiresidue method analyzing 209 pesticides in 24 agricultural commodities has been developed and validated using the original Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) procedure and high performance liquid chromatography-positive electrospray ionization-tandem mass spectrometry (LC-MS/MS) analysis. Using solvent-only calibration standards (SOCSs) and matrix-matched calibration standards (MMCSs), it was demonstrated that a minimal concentration of 5-10 µg/kg (part per billion, ppb) of analytes in matrix is required for the consistent identification of targeted pesticides with two MRM transitions. Method performance was validated by the precision and accuracy results obtained from fortification studies at 10, 25, 100, and 500 ppb and MMCSs. The method was demonstrated to achieve an average recovery of 100 ± 20% (n = 4) for >75% of evaluated pesticides at the low fortification level (10 ppb) and improved to >84% at the higher fortification concentrations in all 24 matrices. Matrix effects in LC-MS/MS analysis were studied by evaluating the slope ratios of calibration curves (1.0-100 ng/mL) obtained from the SOCSs and MMCSs. Principal component analysis (PCA) of LC-MS/MS and method validation data confirmed that each matrix exerts its specific effect during the sample preparation and LC-MS/MS analysis. The matrix effect is primarily dependent on the matrix type, pesticide type and concentration. Some caution is warranted when using matrix matched calibration curves for the quantitation of pesticides to alleviate concerns on matrix effects. The QuEChERS method with LC-MS/MS was used to identify and quantitate pesticides residues, with concentrations ranging from 2.5 to >1000 ppb in a variety of agricultural samples, demonstrating fitness for screening and surveillance applications.


Assuntos
Fracionamento Químico/métodos , Cromatografia Líquida de Alta Pressão/métodos , Produtos Agrícolas/química , Resíduos de Praguicidas/análise , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Acetonitrilas , Frutas/química , Resíduos de Praguicidas/isolamento & purificação , Verduras/química
16.
J AOAC Int ; 94(6): 1741-51, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22320080

RESUMO

Five different mass spectrometers interfaced to GC or LC were evaluated for their application to targeted and nontargeted screening of pesticides in two foods, spinach and ginseng. The five MS systems were capillary GC/MS/MS, GC-high resolution time-of-flight (GC/HR-TOF)-MS, TOF-MS interfaced with a comprehensive multidimensional GC (GCxGC/TOF-MS), an MS/MS ion trap hybrid mass (qTrap) system interfaced with an ultra-performance liquid chromatograph (UPLC-qTrap), and UPLC interfaced to an orbital trap high resolution mass spectrometer (UPLC/Orbitrap HR-MS). Each MS system was tested with spinach and ginseng extracts prepared through a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure. Each matrix was fortified at 10 and 50 ng/g for spinach or 25 and 100 ng/g for ginseng with subsets of 486 pesticides, isomers, and metabolites representing most pesticide classes. HR-TOF-MS was effective in a targeted search for characteristic accurate mass ions and identified 97% of 170 pesticides in ginseng at 25 ng/g. A targeted screen of either ginseng or spinach found 94-95% of pesticides fortified for analysis at 10 ng/g with GC/MS/MS or LC/MS/MS using multiple reaction monitoring (MRM) procedures. Orbitrap-MS successfully found 89% of 177 fortified pesticides in spinach at 25 ng/g using a targeted search of accurate mass pseudomolecular ions in the positive electrospray ionization mode. A comprehensive GCxGC/TOF-MS system provided separation and identification of 342 pesticides and metabolites in a single 32 min acquisition with standards. Only 67 or 81% of the pesticides were identified in ginseng and spinach matrixes at 25 ng/g or 10 ng/g, respectively. MS/MS or qTrap-MS operated in the MRM mode produced the lowest false-negative rates, at 10 ng/g. Improvements to instrumentation, methods, and software are needed for efficient use of nontargeted screens in parallel with triple quadrupole MS.


Assuntos
Cromatografia Líquida de Alta Pressão , Cromatografia Gasosa-Espectrometria de Massas , Resíduos de Praguicidas/análise , Espectrometria de Massas em Tandem , Cromatografia Líquida de Alta Pressão/instrumentação , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia de Fase Reversa/instrumentação , Cromatografia de Fase Reversa/métodos , Cromatografia Gasosa-Espectrometria de Massas/instrumentação , Cromatografia Gasosa-Espectrometria de Massas/métodos , Panax/química , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Spinacia oleracea/química , Espectrometria de Massas em Tandem/instrumentação , Espectrometria de Massas em Tandem/métodos
17.
J Agric Food Chem ; 58(9): 5248-56, 2010 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-20441225

RESUMO

A method for the analysis of pesticides and their metabolites including most of the persistent organic pollutants (POPs) in milk and cream is described. The method was single-laboratory validated through milk fortification in quadruplicate with 34 pesticides, isomers, and metabolites including 12 of the insecticide POPs and their metabolites. Whole cow's milk was fortified at 0.2, 0.4, 1, 2, 10, or 50 microg/kg wet weight and extracted with acetone/cyclohexane/ethyl acetate (2:1:1) with the addition of Mg(2)SO(4) and NaCl. Fat recovered in the extract accurately reflected the fat content of the milk or cream. All test portions were purified on a gel permeation chromatograph (GPC) followed by solid phase extraction (SPE) cleanup on a mixed bed graphitized carbon black (GCB) and primary/secondary amine silica gel (PSA) column before determination using a comprehensive two-dimensional gas chromatograph interfaced to a time-of-flight mass spectrometer. Average recoveries were 77, 72, 73, 66, 77, and 84% for 0.2, 0.4, 1, 2, 10, and 50 microg/kg wet weight whole milk, respectively. The average relative standard deviations for 0.2, 0.4, 1, 2, 10, and 50 microg/kg were 10, 8, 7, 7, 3, and 3%, respectively. The limits of quantification (LOQs) for all pesticides were 0.2 or 0.4 microg/kg wet weight. An archived cream sample collected in 1982 on Oahu, Hawaii, was found to contain only hepatachlor epoxide (HE) and DDE-p,p' at 380 +/- 24 and 69 +/- 17 microg/kg fat, significantly elevated over the current action level of 50 microg/kg fat for HE.


Assuntos
Cromatografia em Gel/métodos , Poluentes Ambientais/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Leite/química , Resíduos de Praguicidas/análise , Animais , Limite de Detecção
18.
J Agric Food Chem ; 58(10): 5884-96, 2010 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-20225896

RESUMO

A multiresidue method for the analysis of 168 pesticides in dried powdered ginseng has been developed using acetonitrile or acetone mixture (acetone/cyclohexane/ethyl acetate, 2:1:1 v/v/v) extraction, solid-phase extraction (SPE) cleanup with octyl-bonded silica (C(8)), graphitized carbon black/primary-secondary amine (GCB/PSA) sorbents and toluene, and capillary gas chromatography-mass spectrometry/selective ion monitoring (GC-MS/SIM) or -tandem mass spectrometry (GC-MS/MS). The geometric mean limits of quantitation (LOQs) were 53 and 6 microg/kg for the acetonitrile extraction and 48 and 7 microg/kg for the acetone-based extraction for GC-MS/SIM and GC-MS/MS, respectively. Mean percent recoveries and standard deviations from the ginseng fortified at 25, 100, and 500 microg/kg using GC-MS/SIM were 87 +/- 10, 88 +/- 8, and 86 +/- 10% from acetonitrile extracts and 88 +/- 13, 88 +/- 12, and 88 +/- 14% from acetone mixture extracts, respectively. The mean percent recoveries from the ginseng at the 25, 100, and 500 microg/kg levels using GC-MS/MS were 83 +/- 19, 90 +/- 13, and 89 +/- 11% from acetonitrile extracts and 98 +/- 20, 91 +/- 13, and 88 +/- 14% from acetone extracts, respectively. Twelve dried ginseng products were found to contain one or more of the following pesticides and their metabolites: BHCs (benzene hexachlorides, alpha-, beta-, gamma-, and delta-), chlorothalonil, chlorpyrifos, DDT (dichlorodiphenyl trichloroethane), dacthal, diazinon, iprodione, quintozene, and procymidone ranging from <1 to >4000 microg/kg. No significant differences were found between the two extraction solvents, and GC-MS/MS was found to be more specific and sensitive than GC-MS/SIM. The procedures described were shown to be effective in screening, identifying, confirming, and quantitating pesticides in commercial ginseng products.


Assuntos
Fracionamento Químico/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Panax/química , Resíduos de Praguicidas/análise , Extratos Vegetais/química , Espectrometria de Massas em Tandem/métodos , Acetona , Acetonitrilas , Indicadores e Reagentes , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Extração em Fase Sólida/métodos
19.
J Agric Food Chem ; 58(10): 5868-83, 2010 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-20199080

RESUMO

A multiresidue method for the analysis of pesticides in fresh produce has been developed using salt-out acetonitrile extraction, solid-phase dispersive cleanup with octadecyl-bonded silica (C(18)), and graphitized carbon black/primary-secondary amine (GCB/PSA) sorbents and toluene, followed by capillary gas chromatography-mass spectrometry in selected ion monitoring mode (GC-MS/SIM) or -tandem mass spectrometry (GC-MS/MS). Quantitation was determined from calibration curves using matrix-matched standards ranging from 3.3 to 6667 ng/mL with r(2) > 0.99, and geometric mean limits of quantitation were typically 8.4 and 3.4 microg/kg for GC-MS/SIM and GC-MS/MS, respectively. Identification was determined by using target and qualifier ions and qualifier-to-target ratios for GC-MS/SIM and two ion transitions for GC-MS/MS. Fortification studies (10, 25, 100, and 500 microg/kg) were performed on 167 organohalogen, organophosphorus, and pyrethroid pesticides in 10 different commodities (apple, broccoli, carrot, onion, orange, pea, peach, potato, spinach, and tomato). The mean percent recoveries were 90 +/- 14, 87 +/- 14, 89 +/- 14, and 92 +/- 14% for GC-MS/SIM and 95 +/- 22, 93 +/- 14, 93 +/- 13, and 97 +/- 13% for GC-MS/MS at 10, 25, 100, and 500 microg/kg, respectively. GC-MS/MS was shown to be more effective than GC-MS/SIM due to its specificity and sensitivity in detecting pesticides in fresh produce samples. The method, based on concepts from the multiresidue procedure used by the Canadian Food Inspection Agency and QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe), was shown to be efficient in screening, identifying, and quantitating pesticides in fresh produce samples.


Assuntos
Frutas/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Espectrometria de Massas em Tandem/métodos , Verduras/química , Calibragem , Contaminação de Alimentos/análise , Inseticidas/análise , Compostos Organofosforados/análise , Piretrinas/análise , Controle de Qualidade , Sensibilidade e Especificidade
20.
Anal Chem ; 81(14): 5716-23, 2009 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-19548696

RESUMO

A method has been developed for the analysis of 170 organohalogen and organophosphorous pesticides, isomers, and metabolites in dried ground ginseng root. Pesticides were extracted with ethyl acetate and purified with gel permeation chromatography (GPC) and primary/secondary amine modified silica (PSA)/graphitized carbon black (GCB) combination SPE column. Each purified pesticide extract was determined by both gas chromatography single quadrupole mass spectrometry using selected ion monitoring (GC-qMS-SIM) and by gas chromatography high resolution time-of-flight mass spectrometry (GC-HR-TOFMS). The geometric mean LOQs using the qMS and TOFMS were 4 and 3 ng/g ginseng, respectively. Mean recoveries from ginseng were 83, 79, and 75% with standard deviations of 4, 5, and 3%, respectively, for 25, 100, and 500 ng/g using GC-qMS-SIM. Mean recoveries using GC-HR-TOFMS were 93, 85, and 81% with mean standard deviations of 7, 7, and 8% for 25, 100, and 500 ng/g, respectively. Seven dried ginseng root products were found to contain combinations of the following pesticides: dacthal, diazinon, DDT, hexachlorobenzene, iprodione, lindane, procymidone, and quintozene (1-460 ng/g). No significant differences were found in the concentrations measured for these pesticides on commercial ginsengs using either of the two GC/MS techniques.


Assuntos
Cromatografia Gasosa/métodos , Halogênios/química , Espectrometria de Massas/métodos , Compostos Organofosforados/análise , Panax/química , Praguicidas/análise , Raízes de Plantas/química , Análise de Alimentos , Isomerismo , Compostos Organofosforados/química , Compostos Organofosforados/isolamento & purificação , Compostos Organofosforados/metabolismo , Praguicidas/química , Praguicidas/isolamento & purificação , Praguicidas/metabolismo , Reprodutibilidade dos Testes
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