Targeted Multiresidue Analysis of Veterinary Drugs in Milk-Based Powders Using Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS)

An analytical method was developed and validated for the determination of 40 veterinary drugs in various milk-based powders. The method involves acetonitrile/water extraction, solid-phase filtration for lipid removal in fat-containing matrices, and analysis using liquid chromatography–tandem mass spectrometry (LC-MS/MS). The limits of quantitation (LOQ) ranged from 0.02 to 82 ng/g. Acceptable recoveries (70–120%, RSD < 20%) were reached for 40 of 52 target compounds at three fortification levels in nonfat milk powder. Similar results were obtained for whole milk powder, milk protein concentrate, whey protein concentrate, and whey protein isolate. This new method will allow for better monitoring of a wide range of veterinary drugs in milk-based powders

Dopant-Assisted Atmospheric Pressure Photoionization of Patulin in Apple Juice and Apple-Based Food with Liquid Chromatography–Tandem Mass Spectrometry

A dopant-assisted atmospheric pressure photoionization (APPI) with liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed to determine patulin in apple juice and apple-based food. Different dopants, dopant flow rates, and LC separation conditions were evaluated. Using toluene as the dopant, the LC-APPI-MS/MS method achieved a linear calibration from 12.5 to 2000 μg/L (<i>r</i>² > 0.99). Matrix-dependent limits of quantitation (LOQs) were from 8 μg/L (solvent) to 12 μg/L (apple juice). [¹³C]-Patulin-fortified apple juice samples were directly analyzed by the LC-APPI-MS/MS method. Other apple-based food was fortified with [¹³C]-patulin, diluted using water (1% formic acid), centrifuged, and filtered, followed by LC-APPI-MS/MS analysis. In clear apple juice, unfiltered apple cider, applesauce, and apple-based baby food, average recoveries were 101 ± 6% (50 μg/kg), 103 ± 5% (250 μg/kg), and 102 ± 5% (1000 μg/kg) (av ± SD, <i>n</i> = 16). Using the suggested method, patulin was detected in 3 of 30 collected market samples with concentrations ranging from 13C]-patulin allowed quantitation using solvent calibration standards with satisfactory precision and accuracy

Determinations for Pesticides on Black, Green, Oolong, and White Teas by Gas Chromatography Triple-Quadrupole Mass Spectrometry

Black, green, white, and Oolong teas, all derived from leaves of <i>Camellia sinensis</i>, 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,β,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

Development and Validation of a Qualitative Method for Target Screening of 448 Pesticide Residues in Fruits and Vegetables Using UHPLC/ESI Q‑Orbitrap Based on Data-Independent Acquisition and Compound Database

A semiautomated qualitative method for target screening of 448 pesticide residues in fruits and vegetables was developed and validated using ultrahigh-performance liquid chromatography coupled with electrospray ionization quadrupole Orbitrap high-resolution mass spectrometry (UHPLC/ESI Q-Orbitrap). The Q-Orbitrap Full MS/dd-MS² (data dependent acquisition) was used to acquire product-ion spectra of individual pesticides to build a compound database or an MS library, while its Full MS/DIA (data independent acquisition) was utilized for sample data acquisition from fruit and vegetable matrices fortified with pesticides at 10 and 100 μg/kg for target screening purpose. Accurate mass, retention time and response threshold were three key parameters in a compound database that were used to detect incurred pesticide residues in samples. The concepts and practical aspects of in-spectrum mass correction or solvent background lock-mass correction, retention time alignment and response threshold adjustment are discussed while building a functional and working compound database for target screening. The validated target screening method is capable of screening at least 94% and 99% of 448 pesticides at 10 and 100 μg/kg, respectively, in fruits and vegetables without having to evaluate every compound manually during data processing, which significantly reduced the workload in routine practice

Multi-mycotoxin Analysis of Finished Grain and Nut Products Using High-Performance Liquid Chromatography–Triple-Quadrupole Mass Spectrometry

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

Multiresidue Pesticide Analysis of Botanical Dietary Supplements Using Salt-out Acetonitrile Extraction, Solid-Phase Extraction Cleanup Column, and Gas Chromatography–Triple Quadrupole Mass Spectrometry

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

Multiresidue Pesticide Analysis of Dried Botanical Dietary Supplements Using an Automated Dispersive SPE Cleanup for QuEChERS and High-Performance Liquid Chromatography–Tandem Mass Spectrometry

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 (<i>r</i>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, <i>n</i> = 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

Multiresidue Pesticide Analysis of Dried Botanical Dietary Supplements Using an Automated Dispersive SPE Cleanup for QuEChERS and High-Performance Liquid Chromatography–Tandem Mass Spectrometry

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 (<i>r</i>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, <i>n</i> = 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

Multi-mycotoxin Analysis of Finished Grain and Nut Products Using Ultrahigh-Performance Liquid Chromatography and Positive Electrospray Ionization–Quadrupole Orbital Ion Trap High-Resolution Mass Spectrometry

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, δ_M, of <±2.0 ppm at 70 000 full width at half maximum (FWHM) mass resolution (<i>R</i>_FWHM). 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 δ_M < ±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

Determination of Multiresidue Pesticides in Botanical Dietary Supplements Using Gas Chromatography–Triple-Quadrupole Mass Spectrometry (GC-MS/MS)

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 (<i>r</i>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