Search

In 2019, the U.S. Department of Agriculture’s (USDA) Food Safety and Inspection Service (FSIS) provided revised guidance for labeling claims of “raised without antibiotics” (RWA) and similar terms for meat and poultry produced in the US. In 2022, Price et al. published a study reporting that 15% of RWA-labeled cattle contained antibiotic residues in urine samples. In 2023, the USDA embarked on the project reported herein to independently determine the extent of antibiotic drug residues present in kidney and liver tissues from slaughtered cattle purported to be RWA. In this study, FSIS inspectors randomly collected kidney and liver tissues from 189 RWA animals in 79 slaughter establishments across the US. The samples were monitored for 185 veterinary drugs multiple times by different means, including liquid-chromatography coupled with tandem mass spectrometry (LC-MS/MS) and quadrupole high-resolution MS with an orbital ion trap instrument (LC-Q/orbitrap). Samples from 37 animals (20%) met the analytical identification criteria for at least one antibiotic confirmed in at least two analyses. Multiple antibiotics were determined in 11 RWA animals. Macrolides (tulathromycin, tildipirosin, tilmicosin, and gamithromycin) were confirmed in 20 (11%) of the RWA animals. The ionophore, monensin, was also confirmed in tissues from 11 samples, with unconfirmed/partial identifications in 8 others. Tetracyclines were confirmed in samples from 12 animals, several of which were found to contain multiple antibiotic residues. One animal each was also found to be positive for sulfamethazine (a sulfonamide antibiotic) and metabolites of penicillin G (a β-lactam antibiotic). Although they are not antibiotics, two anthelmintics (fenbendazole and eprinomectin) were confirmed in tissues from 3 RWA animals. FSIS has informed the slaughter establishments with positive results and advised them to conduct a root cause analysis and implement corrective actions.

Introduced in 2003, the 'quick, easy, cheap, effective, rugged, and safe' (QuEChERS) sample preparation approach has been widely adopted in many applications, particularly in chemical residue analysis of foods. Prior [...]

In the multiclass, multiresidue analysis of pesticides in food and environmental samples, pyrethroid insecticides are generally more difficult to analyze than other types of analytes. They do not ionize well by electrospray ionization, and although they are suitable for analysis by gas chromatography-mass spectrometry (GC-MS), selectivity using standard electron ionization (EI) in GC-MS is often insufficient because the molecular ion is rarely present. Many pyrethroids tend to have the same fragment ions in MS or high-resolution (HR)MS, and similar ion transitions in tandem MS/MS, leading to difficulties in distinguishing different pyrethroids from each other and chemical interferences in complex matrices. In this study, different forms of fast GC coupled with different types of MS detectors were compared for the analysis of up to 15 pyrethroids in barley extracts as a test case to assess which approach was the most advantageous. The three studied GC-MS techniques consisted of Cold EI using supersonic molecular beams in selected ion monitoring (SIM) mode with a single quadrupole instrument; triple quadrupole MS/MS; and HRMS using an orbital ion trap (orbitrap). A higher flow rate was used in Cold EI, and low pressure (LP) GC was employed in the MS/MS and orbitrap methods, to speed up the GC analyses (<10 min chromatograms in all cases). Each technique had some advantages over the others depending on specific pyrethroid analytes in the matrix. Nontargeted LPGC-orbitrap typically yielded the highest selectivity, but it rarely achieved the needed detectability to quantidentify the residues at 10 ng g−1. Cold EI-SIM and LPGC-MS/MS usually met the needed detection limits and generally achieved similar capabilities for the targeted pyrethroids.

Conventional chromatographic peak integration functions rely on complex software and settings, but untrustworthy integrations still routinely lead to time-consuming manual review and reintegrations. Current rugged gas chromatography-tandem mass spectrometry (GC-MS/MS) and liquid chromatography (LC)-MS/MS methods typically only need milligram or microgram amounts of equivalent injected sample to achieve, Peak integration is a fundamental aspect of universal importance in chromatography for analytical purposes (1-3). Many publications for decades have described theory and proposed new practices for chromatographic peak integration [...]

Potatoes are the most highly consumed vegetable in the United States and are the primary source of antioxidants in the American diet. Therefore, technologies and growing methods that aim to enhance the nutritional quality of potatoes can have positive impacts on public health. Based on past success with other food crops, we hypothesized that inoculation with arbuscular mycorrhizal fungi (AMF) would increase both the yield and nutritional quality of potatoes. To test this hypothesis, we grew yellow fleshed (cv. Lehigh) and purple fleshed (cv. Adirondack Blue) potatoes in containers with several monospecific AMF inoculants comprised of Rhizophagus irregularis, Funneliformis mosseae,or Claroideoglumus etunicatum, and one indigenous mixed species population inoculant. Overall, we found that AMF inoculation increased potato tuber yield by up to 23%, antioxidant activity by up to 120%, ergothioneine concentration by up to 9X, and soluble sugar concentration by up to 46%, and that the extent of these increases varied by mycorrhizal species. Future research should examine the extent to which inoculation with the most beneficial AMF species reported here improves yield and nutritional quality in the field setting.

The technique of QuEChERS (quick, easy, cheap, effective, rugged and safe) is only seven years old, yet it is revolutionizing the manner in which multiresidue, multiclass pesticide analysis (and perhaps [...]

Analysis of chemical residues in foods is a big challenge for developing countries due to lack of financial and professional resources needed to meet international quality standards for trade. However, the implementation of simple multiclass, multi-residue methods in monitoring programs can provide significant benefits to save cost, time, and labor. The aim of this project was to investigate the “quick, easy, cheap, effective, rugged, safe, efficient, and robust” (QuEChERSER) mega-method for the fatty muscle matrices of goat and lamb. To achieve wide analytical scope covering pesticides, environmental contaminants, and veterinary drugs, extracts were analyzed by both ultrahigh-performance liquid and low-pressure gas chromatography (UHPLC and LPGC) coupled with tandem mass spectrometry (MS/MS). The QuEChERSER mega-method was validated in ovine (goat) and caprine (lamb) muscles at four different spiking levels with 10 replicates per level for a total of 330 analytes and metabolites, consisting of 225 pesticides, 89 veterinary drugs, and 16 polychlorinated biphenyls (PCBs). In the case of LPGC-MS/MS (preceded by automated “instrument-top sample preparation”), 92% and 82% of the analytes met the data quality objectives of 70–120% recovery and <20% RSD for goat and lamb, respectively. For UHPLC-MS/MS, 95% and 92% of the analytes met the acceptable validation criteria in goat and lamb, respectively. Thus, the QuEChERSER mega-method has been demonstrated to be a useful streamlined approach to more efficiently replace multiple methods currently used to cover the same analytical scope.

In this work, a new mega-method of sample preparation called “QuEChERSER” (more than QuEChERS) is being presented for the first time. Fast, efficient, and cost-effective analysis of chemical contaminants in meat is useful for international trade, domestic monitoring, risk assessment, and other purposes. The goal of this study was to develop and validate a simple high-throughput mega-method for residual analysis of 161 pesticides, 63 veterinary drugs, 24 metabolites, and 14 legacy environmental contaminants (polychlorinated biphenyls) in bovine muscle for implementation in routine laboratory analyses. Sample preparation of 2 g test portions entailed QuEChERS-based extraction with 10 mL of 4:1 (v/v) acetonitrile/water, and then 204 μL was taken, diluted, and ultracentrifuged prior to analysis of veterinary drugs and pesticides by ultra-high-performance liquid chromatography−tandem mass spectrometry. The remaining extract was salted out with 4:1 (w/w) anhydrous MgSO4/NaCl, and 1 mL was transferred to an autosampler vial for automated mini-cartridge solid-phase extraction (Instrument Top Sample Preparation) cleanup with immediate injection using fast low-pressure gas chromatography−tandem mass spectrometry analysis. The automated cleanup and both instruments were all operated in parallel in 13−15 min cycle times per sample. Method validation according to United States Department of Agriculture requirements demonstrated that 221 (85%) of the 259 analytes gave average recovery between 70 and 120% and interday relative standard deviation of ≤25%. Analysis of a certified reference material for veterinary drugs in freeze-dried bovine muscle was also very accurate, further demonstrating that the QuEChERSER mega-method can be implemented to save time, labor, and resources compared to current practices to use multiple methods to cover the same analytical scope.

The goal of this study was to develop and validate a new method for simultaneous determination of 106 veterinary drugs and 227 pesticides and their metabolites plus 16 polychlorinated biphenyls (PCBs) at and below their regulatory levels established for catfish muscle in the European Union and U.S.A. To do this, two different QuEChERS-based methods for veterinary drugs and pesticides and PCBs were modified and merged into a single mega-method dubbed “QuEChERSER” (more than QuEChERS), which is presented here for the first time. The mega-method was validated in catfish at four different spiking levels with 10 replicates per level. Sample extraction of 2 g test portions was made with 10 mL of 4:1 (v/v) acetonitrile/water, and then an aliquot was taken for ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) analysis of 106 veterinary drugs and 125 pesticides, including metabolites. The remaining extract after salting out was subjected to automated mini-solid-phase extraction cleanup (Instrument Top Sample Preparation) for immediate injection in low-pressure gas chromatography–tandem mass spectrometry (LPGC–MS/MS). The cleanup was conducted in parallel with the 10 min LPGC–MS/MS analysis for 167 PCBs, pesticides, and metabolites, which was conducted in parallel with the 10 min UHPLC–MS/MS analysis for 231 analytes to increase sample throughput (49 analytes were included in both techniques). In MS/MS, three ion transitions were monitored for nearly all targeted analytes to provide unambiguous identification as well as quantification. Satisfactory recoveries (70–120%) and relative standard deviations of ≤20% were achieved for 98 (92%) of the veterinary drugs and their metabolites and for 222 (91%) of pesticides, metabolites, and PCBs, demonstrating that the developed method is applicable for the analysis of these contaminants in fish as part of regulatory monitoring programs and other purposes.

In this study, sample processing of bulk commodities using an efficient one-step comminution procedure with liquid nitrogen (LN2) was devised and assessed in the analysis of pesticide residues in fruits and vegetables. LN2was added to the fresh samples from a tank by opening a valve, and the standard food chopper was kept in a laboratory hood to reduce safety risks. Test portions of four replicates each of 0.25, 0.5, 1, 2, 5, 10, and 15 g were taken from eight fruits and vegetables (tomato, squash, broccoli, apple, grape, peach, green bean, and cucumber) individually comminuted with LN2. For comparison without comminution, similar test portions of a reconstituted freeze-dried certified reference material of pesticides in cucumber were also analyzed by the same method. More than 100 pesticides were monitored by both ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) and instrument top sample preparation (ITSP) + fast low-pressure gas chromatography–tandem mass spectrometry (LPGC–MS/MS). A new version of QuEChERS-based sample preparation was followed, in which 5 mL of 4:1 (v/v) acetonitrile/water per gram of sample is used for extraction and 200 μL of initial extract is quickly evaporated, reconstituted in water, and ultracentrifuged for UHPLC–MS/MS analysis. For ITSP+LPGC–MS/MS, another portion of the initial extract undergoes salt-out partitioning with 4:1 (w/w) anhydrous MgSO4/NaCl and the upper layer extract is transferred to an autosampler vial for automated cleanup and analysis in parallel. Quality control spikes were made during the comminution, extraction, cleanup, and analysis steps to isolate and estimate the individual and overall measurement uncertainties of the approach. The recommended test portion size is 2 g for routine monitoring by this approach, but results demonstrated that subsamples as low as 0.5 g typically gave overall biases and relative standard deviations of <10% for nearly all pesticides, commodities, and methods, which is 3–5% lower than previously evaluated sample processing and analytical methods. This approach can be used to improve data quality, laboratory efficiency, and sample throughput in routine monitoring programs for regulatory, risk assessment, and other purposes.

With the monitoring of hundreds of pesticides in food and feed, the comminution step is equally crucial as any other to achieve valid results. However, sample processing is often underestimated in its importance and practical difficulty to produce consistent test portions for analysis. The scientific literature is rife with descriptions of microextraction methods, but ironically, sample comminution is often ignored or dismissed as being prosaic, despite it being the foundation upon which the viability of such techniques relies. Cryogenic sample processing using dry ice (−78 °C) is generally accepted in practice, but studies have not shown it to yield representative test portions of <1 g. Remarkably, liquid nitrogen has rarely been used as a cryogenic agent in pesticide residue analysis, presumably as a result of access, cost, and safety concerns. However, real-world implementation of blending unfrozen bulk food portions with liquid nitrogen (−196 °C) using common food processing devices has demonstrated this approach to be safe, simple, fast, and cost-effective and yield high-quality results for various commodities, including increased stability of labile or volatile analytes. For example, analysis of dithiocarbamates as carbon disulfide has shown a significant increase of thiram recoveries (up to 95%) using liquid nitrogen during sample comminution. This perspective is intended to allay concerns among working laboratories about the practical use of liquid nitrogen for improved sample processing in the routine monitoring of pesticide residues in foods and feeds, which also gives promise for feasible test sample size reduction in high-throughput miniaturized methods.

Although supercritical fluid chromatography (SFC) is often useful for the analysis of nonpolar lipids, this study demonstrates for the first time an analytical SFC method with detection by ion trap mass spectrometry (MS/MS) for large and polar lipids, such as lipid A, using a simple, fast, economical, and environmentally-friendly approach. Chemical derivatization of the lipid A was not needed, and the SFC-MS/MS analysis only took 2 min per injection. The method was evaluated by analyzing lipid A spiked into two representative food matrices, lettuce and ground beef. For sample preparation, a simple shaking procedure with 3/1 (v/v) chloroform–methanol was used. %Recoveries in spiked samples were 74 ± 10 at 10–30 μg g−1in lettuce and 110 ± 5 in meat at 30 μg g−1.

The technique of QuEChERS (quick, easy, cheap, effective, rugged and safe) is only seven years old, yet it is revolutionizing the manner in which multiresidue, multiclass pesticide analysis (and perhaps beyond) is performed. Columnist Ron Majors interviews inventors Michelangelo Anastassiades and Steve Lehotay about the successes, challenges and potential future directions of this growing sample preparation technique. [ABSTRACT FROM AUTHOR]

Unlike quantitative analysis, which must commonly undergo an extensive method validation process in labs to assure quality of results, the quality of the qualitative results in the analysis of pesticide residues in food is generally ignored in practice. Instead, chemists tend to rely on advanced MS techniques and general subjective guidelines or fixed acceptability criteria when making analyte identifications. All analytes and matrices have unique characteristics that make this current approach less effective than desirable in many real‐world situations. Just as performed in quantitative method validation studies, collection of distinguishing factors of selectivity versusconcentration, such as analyte retention time variabilities, ion ratios, matrix background evaluations, choice of ions, and the number of ions to use, provides specific information about the particular application to assess its quality. Empirical analysis of many blind samples to check the rates of false positives and negatives should be performed, at least to better evaluate LOD and reduce the chances of a serious qualitative problem. Familiarization training and review of results by the analyst(s) increase performance, and in any case, the traditional use of two independent analyses should still be relied upon to make chemical confirmations. In this study, an experimental approach to evaluate GC‐MS using SIM with a quadrupole instrument and an MS/MS (ion trap) was conducted to assess the qualitative factors of both methods for 16 pesticides fortified (or not) in carrot extracts. Rates of false positives and negatives were compared using different identification criteria, and no single set of conditions was found to be superior for all analytes.

This paper describes the use of a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for extraction and cleanup of 16 pesticide residues of interest in olives and olive oil. These products contain a high lipid content, which can adversely affect pesticide recoveries and harm traditional chromatographic systems. For extraction, the main factors (oil and water content) were studied and optimized in experiments to maximize pesticide recoveries. Dispersive SPE with different sorbents was also investigated to minimize matrix coextractives and interferences. For analysis, a new automated DSI device was tested in GC‐MS to avoid nonvolatile coextractives from contaminating the instrument. LC‐MS/MS with positive ESI was used for those pesticides that were difficult to detect by GC‐MS. The final method was validated for olives in terms of recoveries, repeatabilities, and reproducibilities using both detection techniques. The results demonstrated that the method achieved acceptable quantitative recoveries of 70–109% with RSDs <20% for DSI‐GC‐MS and 88–130% with RSDs <10% for LC‐MS/MS, and LOQ at or below the regulatory maximum residue limits for the pesticides were achieved.

A novel, simple, and inexpensive approach to sorptive extraction, which we call solvent in silicone tube extraction (SiSTEx), was applied to pesticide residue analysis and its effectiveness and efficiency were evaluated. In SiSTEx, which is a form of open tubular sorptive extraction, a piece of silicone tubing (4 cm long, 1.47 mm ID, 1.96 mm OD in this study) is attached to the cap of a 20 mL glass vial that contains the aqueous sample. The tubing is plugged at the end dangling in the sample solution, and MeCN (e. g., 40 μL) added by syringe to the inner tube volume through a septum in the cap. A stir‐bar is used to mix the sample for a certain time (e. g., 60 min), which allows chemicals to partition into the tubing where they diffuse across the silicone and partition into the MeCN. The final MeCN extract is then analyzed for the concentrated analytes. In this study, the SiSTEx approach was evaluated for the analysis of organophosphorus (OP) and organochlorine (OC) pesticides in fruits and vegetables using GC/pulsed flame photometric (PFPD) and halogen specific (XSD) detectors for analysis. The produced samples were initially extracted by a rapid MeCN procedure, and 5 mL of the initial extract was diluted four‐fold with water to undergo sorptive extraction for 60 min. The final extract was analyzed by GC/PFPD + XSD for 14 OP and 22 OC pesticides. This simple approach was able to detect 26 of the 36 pesticides at 10 ng/g or less original equivalent sample concentration with average reproducibility of 11 %RSD. For those 26 pesticides, a 44‐fold lower detection limit on average was achieved in matrix extracts using SiSTEx despite the four‐fold dilution with water.

Automated large‐volume direct sample introduction, or difficult matrix introduction (DMI), was investigated in the determination of 44 pesticide residues possessing a wide range of physico‐chemical properties (volatility, polarity, pKa) in fruit‐based baby food by means of gas chromatography–mass spectrometry (GC–MS) with a quadrupole mass analyzer. DMI has advantages over traditional injection because large volumes (up to 30 μL) of potentially dirty sample extracts can be injected into the GC–MS, but nonvolatile matrix components that would normally contaminate the inlet are removed after every injection. The extra matrix and glass surfaces involved in DMI, however, make the system more prone to the matrix‐induced chromatographic enhancement effect, which adversely affects quantification of several pesticides. To overcome this problem, matrix‐matched calibration standards and/or the use of analyte protectants were applied in the DMI approach, and the analysis of extracts was also compared before and after undergoing clean‐up by dispersive solid‐phase extraction. For best quantification, clean‐up was still needed, and the combination of matrix‐matching with analyte protectants gave the most reproducible results. Depending on the application, however, the addition of analyte protectants (a mixture of 3‐ethoxy‐1,2‐propanediol, L‐gulonic acid 3‐lactone, and D‐sorbitol) to sample extracts and calibration standards in solvent (non‐matrix matched), gave satisfactory quantification for most of the 44 pesticides tested. The lowest calibration levels for 34 of the 44 pesticides were ⩽10 ng/g, which meets the standard required by the European Union Baby Food Directive (2003/13/EC).

Sample extracts of various commodities, obtained using the US Food and Drug Administration (acetone extraction) and Canadian Pest Management Regulatory Agency (acetonitrile extraction) methods for pesticides were subjected to cleanup with solid phase extraction (SPE) columns. Graphitized carbon black (GCB), octadecylsilyl (C‐18), strong anion exchange (SAX), aminopropyl (—NH2), and primary secondary amine (PSA) SPE columns were evaluated. The relative sample cleanup provided by these SPE columns was evaluated using gas chromatography with electron capture, flame photometric, and mass spectrometric detection. The —NH2and PSA columns were found to provide the most effective cleanup, removing the greatest number of sample matrix interferences. The GCB columns removed most of the visible plant pigment in the extracts, but did little to eliminate the fatty acid matrix interferences “seen” by the detectors. Likewise, the C‐18 and SAX columns did little to eliminate matrix interferences. Using an acetone extraction followed by a PSA cleanup, both polar and nonpolar pesticides present in samples at 1.0 ng/g could be recovered.

A method using simultaneous pulsed flame photometric (PFPD) and micro-electron capture detection (μECD) in gas chromatography (GC) was developed and validated for the analysis of 23 organophosphorus (OP) and 17 organochlorine (OC) pesticides in animal fat. The method entailed the extraction of animal tissue (mixed with twice the sample weight of sodium sulfate) with 7 mL ethyl acetate per 1 g tissue. After the blending step, the extract was centrifuged and 3 mL cyclopentane was added to a 7 mL portion of the extract. A 2.5 mL portion was injected into a 2 cm ID×22.5 cm Biobeads S-X3 gel permeation chromatography column (4.5 mL/min flow rate of 70/30 ethyl acetate/cyclopentane). A 36 mL fraction (from 8 to 16 min) was collected, evaporated, and solvent-exchanged to 1 mL final volume in iso-octane. The GC/PFPD + μECD system used a single injector and column, but the flow was split after the chromatographic separation to the two detectors. The final extract was injected (2 μL) into the GC/PFPD + μECD system for simultaneous analysis of the OP and OC analytes. The PFPD was used in the phosphorus-only mode to detect OPs and the μECD mainly detected halogenated pesticides but a few N-containing OPs could be sensitively detected with it as well. Recoveries were 60–70% for the bulk majority of pesticides except for methamidophos, acephate, and omethoate which are more difficult in GC analysis due to their more polar nature. Fenthion and phorate also gave more variable recoveries, presumably due to their degradation to sulfones and sulfoxides. In fortification recovery experiments at several different concentrations over multiple days, reproducibilities of 10–20% relative standard deviation were achieved, and limits of quantitation were typically 10–20 ng/g.

A diode-laser-based indirect fluorometric detector that monitors a near infrared dye, IR 125, added to the mobile phase for reversed-phase high-performance liquid chromatography, was evaluated. Analytical measurements of n-alkyl alcohols were made by measuring the induced change in the IR 125 fluorescence signal at the alcohol retention times. Limits of detection were on the order of 10−8mol injected. Several isocratic separations were carried out at different IR 125 concentrations in different acetonitrile: pH 6 sodium phosphate aqueous buffer mobile phase ratios. The results indicate that a small dye/ analyte transfer ratio is limiting the capabilities of the detector. However, the low noise and highly selective excitation characteristics of the diode laser present the potential for this detection scheme to attain a detection limit of 10−11M at the detector for analytes with a transfer ratio of 1.

The simultaneous extraction of relatively polar and nonpolar pesticides has been problematic in multiresidue analysis using supercritical fluid extraction (SFE) with carbon dioxide. In fruit and vegetable samples, which typically contain 80–95% water, moisture acts to increase SFE recoveries of many polar pesticides, but a drying agent should be used to control water in SFE. Hydromatrix, a prevalent drying agent, has many desirable characteristics, but it reduces recovery of certain important pesticides, such as methamidophos, acephate, and omethoate. MgSO₄ has been shown previously to be applicable for the extraction of methamidophos and six other pesticides, but MgSO₄ has practical disadvantages in its use. In this study, properties and SFE results with the individual drying agents and their combination were evaluated. Simultaneous recoveries for polar and nonpolar pesticides were achieved for 71 pesticides fortified in apple using a mixture of 2 + 1 + 2 MgSO₄·H₂O–Hydromatrix–sample for extraction. The advantages of each drying agent were maintained by their combination. The analysis of real samples, however, showed that more study was needed to improve recoveries of nonpolar pesticides.

An analytical method not requiring a mercury column cleanup step is described for the isolation and detection of four thyreostatic agents in meat tissue. The use of these growth promotants in livestock has been banned by regulatory agencies. The meat tissue is homogenized with acetonitrile-water, centrifuged, and the supernatant is partitioned with petroleum ether. The acetonitrile-water is concentrated and then passed through a silica-gel column. The solvent is then removed and the residue derivatized with N-methyl-N-(trimethylsilyl)- trifluoroacetamide. The total amount of organic solvent used for the analysis is merely 35 mL. The derivatized thyreostats are detected and quantitated by gas chromatography (GC) equipped with a nitrogen-phosphorus detector. Percent recoveries from fortified meat tissue (n = 6) at the 0.1-µg/g (parts per million) level are 93.5 ± 2.9 for 2-thiouracil, 90.3 ± 3.0 for tapazole, 87.5 ± 2.9 for 6-methyl-2-thiouracil, and 85.1 ± 5.8 for 6-n-propyl-2-thiouracil. For the confirmation of analyte identities, GC-tandem mass spectrometry with an ion-trap instrument is used. The estimated minimum level for a reliable measurement is 0.050 µg/g in meat tissue.