bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Pyrantel in Swine Liver by Flame Ionization Gas Chromatography and Confirmation by Gas Chromatography /Mass Spectrometry
Authors: Tai Susan S.C , Cargile Nancy , Barnes Charlie J , Kijak Philip
Published: February 2020

During an evaluation of the gas chromatography/mass spectrometry (GC/MS) confirmatory procedure of Lynch and Bartoluccl for pyrantel residues in swine tissues, we developed a GC flame Ionization method for quantltatlng pyrantel residues In extracts of swine liver. The method was subjected to trial principally In the laboratories of Biospherics, Inc., using control liver, fortified control liver, and Incurred liver tissue samples. Although the method does not meet all of the current Food and Drug Administration criteria, it compares favorably to the official determinative method. Portions of the same extract can be used for quantitation and for GC/MS confirmation, true recoveries appear to be slightly higher, and an internal standard Is not required. The precision of this method equals or exceeds that of the official determinative method.
Determination of Gentian Violet, Its Demethylated Metabolites, and Leucogentian Violet in Chicken Tissue by Liquid Chromatography with Electrochemical Detection
Authors: Roybal Jose E , Munns Robert K , Hurlbut Jeffrey A , Shimoda Wilbert
Published: February 2020

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 acetonitrlle/ 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 carboxyl- Ic acid cation exchange column and then eluted with 0.02% HCI In methanol. GV, Its metabolites, and LGV are determined by liquid chromatography using Isocratlc elution with a buffered mobile phase from a cyano column and amperometrlc 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 metabollte(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.
Liquid Chromatographic Determination Of Three Sulfonamides In Animal Tissue And Egg
Authors: Horii Shozo , Momma Chie , Miyahara Kayoko , Maruyama Tsutomu , Matsumoto Masao
Published: February 2020

Sulfonamides are widely used as a feed additive in animal production In Japan. The present paper is a determination of 3 sulfonamides: sulfamethazine (SMZ), sulfamonomethoxlne [SMX, 4-amino-/V-(3-methoxypyrazlnyl)-benzenesulfonamlde], and suifadimethoxine (SDX) in animal tissue and egg by liquid chromatography (LC). Tissues were extracted with acetonltrlle and fat was removed by liquid/liquid partition. The sulfonamides were purified by an ODS cartridge column; then each compound was separated by an ODS LC column and detected at 268 nm. Quantification levels were 0.02 ppm for SMZ and SMX, and 0.04 ppm for SDX; detection limits were 0.01 ppm for SMZ and SMX, and 0.02 ppm for SDX. Calibration curves were linear between 2 and 40 ng for SMZ and SMX, and between 4 and 80 ng for SDX. Recoveries from muscle and egg samples spiked with 1-2 /μg/10 g were 8 1 - 98%.
A Single Cell Protein as Standard Reference Material for Determination of Amino Acids, Fatty Acids, and Elements in Foods
Authors: Aziz Abdul , Abu-Dagga Faisal
Published: February 2020

A commercially available single-cell protein (Pruteen) was analyzed for amino acids, fatty acids, and major, minor, and trace-element composition after storage at room temperature and at 4°C over a period of 5 years. The purpose was to assess its suitability as an organic-nutrient standard reference material for food analysis. The material showed longterm stability and is, therefore, recommended for interlaboratory certification studies.
Multiresidue Assay for Benzimidazole Anthelmintics by Liquid Chromatography and Confirmation by Gas Chromatography/Selected-Ion Monitoring Electron Impact Mass Spectrometry
Authors: Wilson Roger T , Groneck Joseph M , Henry Carolyn A , Rowe Loyd D
Published: February 2020

A multiresidue method utilizing all-disposable labware has been developed for 8 benzimidazole anthelmintics from ovine, bovine, and swine muscle and liver tissues. After an Initial extraction with ethyl acetate and subsequent evaporation, a 3-component extraction using hexane, ethanol, and 0.2N HCI was used for final cleanup. Clean extracts were produced for separation and determination by reverse-phase liquid chromatography at 298 nm, using methanol and aqueous buffer as mobile phase. A synthesized internal standard, 2-(n-butylmercapto)benzlmldazole, was used for quantitation of all drugs. Results are Included along with statistical information verifying the performance of the method. Spiked control tissues and Incurred drug tissues were used for an Intralaboratory study with a concentration range of 50-1470 ppb. A series of standard curves at 0, 50, 100, and 200 ppb were analyzed. Overall recovery at the 100 ppb level averaged 92% (CV 8%) In liver tissues, across all 3 species and 88% (CV 5%) in muscle tissues across all 3 species. Results were confirmed by gas chromatography/mass spectrometry with acid hydrolysis of the remaining extract In 2N HCI followed by re-extractlon of the amine and derivatlzation to the ferf-butyldimethylsilyl derivative. The anthelmintics were Identified by gas chromatography/selected ion monitoring electron-Impact mass spectrometry. Ion ratio measurements were taken and compared to standard material. CVs averaged 10% or less for all drugs tested.
Gas Chromatographic Determination and Pattern Recognition Analysis of Methanol and Fusel Oil Concentrations in Whiskeys
Authors: Wilson Linda A , Ding Jia H , Woods A Edwin
Published: February 2020

A more efficient determination of methanol and fusel oil in 4 types of whiskeys was accomplished using gas chromatography and temperature programming. Carbopack C with 0.2% Carbowax 1500 (Supelco, Inc., Bellefonte, PA) produced baseline separation of 13 aliphatic alcohols containing 5 carbons or less. A comparison of methanol and fusel oil concentrations between various types of whiskeys Indicates that bourbon and sour mash whiskeys contain considerably more fusel oil (275 ± 1 2 and 265 ± 5 mg/100 mL, respectively) than blended and scotch whiskeys (47 ± 5 and 114 ± 7 mg/100 mL, respectively). All concentrations were corrected to 100 proof. A statistical pattern recognition analysis of the data showed that fusel oil components (1-propanol, 2- methyl-1-propanol, 2-methyl-1-butanol, and 3-methyl-1-butanol) and methanol could be used to distinguish between bourbon-sour mash, blended, and scotch whiskeys. Bourbon and sour mash whiskeys were indistinguishable by fusel ollmethanol analysis. A significant increase in methanol content occurred In bourbon and sour mash whiskeys after bottles were opened and reseaied for up to 58 months; fusel oil content remained essentially unchanged.
Moisture Analysis in Forage by Near-Infrared Reflectance Spectroscopy: Collaborative Study of Calibration Methodology
Authors: Windham William R , Barton Franklin E
Published: February 2020

Fifteen collaborating laboratories analyzed 16 forage samples including 3 blind duplicate pairs for moisture by air-oven (AO) method 7.007 (14th Ed.; 930.15, 15th Ed.) and nearinfrared reflectance spectroscopy (NIRS). Laboratories performed method 7.007 on 50 calibration samples and applied the NIRS calibration method Independently. NIRS moisture equations were used to predict the 16 test samples, and the values were compared to those for method 7.007. Moisture concentration of the test samples ranged from approximately 6 to 16%. Within-laboratory repeatability (sr) ranged from 0.10 to 0.18% and 0.16 to 0.39% for NIRS and method 7.007, respectively. Between-laboratory reproducibility (sR) ranged from 0.22 to 0.57 and 0.29 to 0.57 for NIRS and method 7.007, respectively. Repeatability relative standard deviations (RSDr) for the NIRS and AO methods ranged from 1.18 to 1.50% and 1.84 to 3.68%, respectively. The range in the average reproducibility relative standard deviations (RSDR) for the NIRS and AO methods were 1.29-7.49% and 3.64-6.66%, respectively. The NIRS method demonstrated consistently lower wlthln-laboratory RSDr agreement and between-laboratory variabilities equal to method 7.007. Thereby, we demonstrated that NIRS can be used as a standard method for the determination of 6-16% moisture In forages. The method has been adopted official first action by A0AC.
Determination of Benzene in Polypropylene Food-Packaging Materials and Food-Contact Paraffin Waxes
Authors: Varner Sandra L , Hollifield Henry C , Andrzejewski Denis
Published: February 2020

An analytical procedure was developed for determination of benzene in polypropylene food packaging and was adapted for determination of benzene in commercial paraffin waxes Intended for food-contact use. The polymer was dissolved in hexadecane at 150°C. The wax was melted in an 80°C oven. A simple helium-sparging apparatus was used to remove the volatile chemical from the polymer or wax. The contaminant was collected In methanol, distilled water was added, and the resulting solution was analyzed by headspace gas chromatography. The Instrument was equipped with a 30 m fused silica open tubular capillary column and a photoionization detector. Average recoveries of benzene from polymer and paraffin wax at low parts-per-billion concentrations were 63 and 70%, respectively. Limits of detection and quantitation for analysis of polypropylene were 8 and 17 ppb, respectively; the limit of quantitation for analysis of paraffin wax was 2 ppb. in several commercial polypropylene products examined, benzene levels ranged from none detected to 426 ppb. In 3 commercial waxes examined, concentrations of 16-73 ppb benzene were determined. The presence of benzene was confirmed by gas chromatography/mass spectrometry
Gas Chromatographic Method for Determination of Dimethylamine, Trimethylamine, and Trimethylamine Oxide in Fish-Meat Frankfurters
Authors: Fiddler Walter , Doerr Robert C , Gates Robert A
Published: February 2020

A method Is described for analysis of minced fish-meat and surlmi-meat frankfurters for dimethylamine (DMA), trimethyiamine (TMA), and trimethyiamine oxide (TMAO) using a headspace-gas chromatographic technique. After simple acid extraction and addition of NaOH, the headspace was directly Injected Into a gas chromatograph by a gas-tight syringe. DMA and TMA were separated on a Chromosorb 103 column and detected by a flame Ionization detector. TMAO was measured as TMA after Zn reduction. Repeatability of the method for DMA, TMA, and TMAO was 6.6,1.0, and 18.8 ppm, respectively. The method was applicable to Alaska pollock-meat and Atlantic menhaden-meat frankfurters, unwashed, and washed mince and surlml.
Liquid Chromatographic Method for Selegiline Hydrochloride and Related Compounds in Raw Materials and Tablets
Authors: Beaulieu Normand , Cyr Terry D , Graham Susan J , Lovering Edward G
Published: February 2020

A liquid chromatographic method has been developed for determination of selegiline hydrochloride and related substances in drug raw material and tablet formulations. The method resolves 3 known related compounds from the drug with a limit of quantitation of less than 0.05%. Drug raw material and tablet samples contained ca 0.2 and 0.6% impurities, respectively. These included some related compounds, the identities of which were confirmed by gas chromatography with a Fourier transform Infrared detector.
Turbidimetric Assay for Tetracyclines in Feeds Using a Microtiter Plate System
Authors: Brady Marietta Sue , Katz Stanley E
Published: February 2020

The microtiter plate system for turbidimetric assay of chlortetracycline (CTC) and oxytetracycline (OTC) levels in feeds uses a 96 well microtiter plate, a multichannel pipette, and an ELISA reader to measure turbidity. Feeds are extracted for both tetracyclines using AOAC extraction systems. For CTC, the range of the standard curve is 0.001-0.005 μg CTC/ mL; for OTC, the range is 0.004-0.016 μg OTC/mL. Repeatability of CTC assays, as shown by the coefficient of variation (CV), ranged from 0.54 to 5.65% for same-day assays and from 2.01 to 9.39% for assays on different days. For OTC, CVs ranged from 2.69 to 10.01% for same-day assays and 3.24 to 9.08 % for different-day assays. Average recoveries for CTC were 108.7% for same-day assays and 106.8% for different-day assays; for OTC, average recoveries were 112.4% and 106.5% for same-day and different-day assays, respectively.
Defined Substrate Technology Method for Rapid and Specific Simultaneous Enumerationof Total Coliforms and Escherichia coli from Water: Collaborative Study
Authors: Edberg Stephen C , Allen Martin J , Smith Darrell B
Published: February 2020

The defined substrate technology (DST) method Is a reagent system designed to enumerate specific target microbes(s) from a mixture of bacteria. The system simultaneously enumerates total coliforms and Escherichia coll directly from a water sample. The reagent contains o-nitrophenyl-β-D-galactopyranoside (ONPG), which is hydrolyzed by total conforms to produce a yellow chromogen, and 4-methylumbelllferyl-β-D-glucuronide (MUG), which is hydrolyzed and fluoresces when E. coll organisms grow. Noncoliform bacteria are suppressed and cannot metabolize the indicator nutrients. Nine laboratories participated in a field evaluation of the method, which covered a wide range of surface and subsurface water sources and water-processing modalities, including the examination of natural samples. The DST system was compared to multiple-tube fermentation (MTF) (quantitative) and presence-absence (P-A) (qualitative) Standard Methods formats. Comparison of water samples from natural sources by using the most probable number (MPN) procedure showed that the DST test was equivalent to the currently used MTF test. Results from the DST and the qualitative P-A procedure showed that these tests agreed with each other in 94% of the water samples analyzed. Specificity of the DST method was established by subculturing a species consistent with a total conform or E. coll from each positive tube. Eight laboratories participated in a collaborative study of the method. Each laboratory received 3 concentrations of E. coll (organisms/100 mL): 10 (low); 60 (medium); and 120 (high). The DST test was inoculated from a split sample of each bacterial density In parallel with Standard Methods brilliant green lactose broth. Statistical analyses for repeatability and reproducibility showed the DST system to be equivalent to currently used standard methods. The DST method has been adopted official first action by AOAC for detection and enumeration of total coliforms and E. coll in water.
Evidence of an Unusual Pattern of Polychlorinated Biphenyls in the Serum of Some Residents and Canines in Paoli, Pennsylvania
Authors: Burse Virlyn W , Groce Donald F , Korver Margaret P , Caudill Samuel P , McClure Patricia C , Lapeza Chester R , Head Susan L , Schilling Rebecca J , Farrar Jeffrey A , Ostrowski Stephanie R , Mortensen B Kim , Maher John P , Russell Harold L , Sievila Sara
Published: February 2020

The present study uses gas liquid chromatography (GLC) electron capture detection with packed and capillary columns to detect polychlorinated biphenyls (PCBs) in serum samples from people living near the electric car repair and maintenance facility of the Southeastern Pennsylvania Transit Authority in Paoli, Pennsylvania. Most of the cohort surveyed had serum patterns similar to patterns for Aroclor 1260 (AR 1260); a small portion (3/69) had patterns Indicative of an AR with higher chlorlnation (e.g., AR 1268). In addition to analyzing serum samples from humans, we also analyzed serum samples from canines (pets of some of the subjects). In general, the serum pattern for canines was less descriptive for AR 1260 than the pattern for humans; however, the pattern for several canines (9/16) was that of the higher chlorinated PCBs (e.g., AR 1268). By using mass spectrometry and capillary column GLC, we confirmed the presence of high molecular weight polychlorinated congeners in both human and animal samples. We were not able to show a statistically significant relationship between serum patterns of PCBs In canines and their owners or between canines and certain behavioral traits (e.g., runs free, retrieves, hours outside, hours Inside). However, the correlation between PCBs quantified as AR 1268 and canines' residence time was statistically significant.
Liquid Chromatographic Determination of Tolnaftate in Commercial Products
Authors: Thompson Richard D , Carlson Marvin
Published: February 2020

A liquid chromatographic (LC) method for the determination of the antifungal agent tolnaftate was developed. Isolation of the analyte was achieved by direct extraction or dilution with acetonltrlle-water (80 + 20) followed by reverse-phase liquid chromatography using a C18 column. The mobile phase was acetonltrlle-water (80 + 20) acidified with phosphoric acid. Detection was by UV absorption at a wavelength of 257 nm. The proposed procedure was applied to 20 consumer products comprising 6 formulation types, including solutions, powders, liquid and powder aerosols, creams, and gels. The precision (RSD) for the products ranged from 0.23 to 1.16% (n = 5), and recoveries via fortification ranged from 98.1 to 103.0%. Six different brands of C18 columns were evaluated for use with the method. The overall simplicity and versatility of the method suggest possible adaptations to both regulatory and quality-control situations.
A Rapid 13C/12C Test for Determination of Corn Syrups in Honey
Authors: Brookes Steven T , Barrie Andrew , Davies Jonathan E
Published: February 2020

The AOAC official method for detection of corn syrup products in honey measures the 13C/12C ratio (δ13C) (978.17). In the official method, a suspect honey is combusted off-line to C02 gas for analysis on a dual-inlet isotope ratio mass spectrometer (IRMS). The procedure is manual, requires liquid N2, and takes 20-50 min/sample. In the present study, we examine a recently developed alternative, automated 15N 13C analysis mass spectrometry (ANCA-MS). This procedure combusts and analyzes 66 samples in a batch and takes only 5 min/sample. We used both ANCA-MS and IRMS with offline combustion to analyze 6 honeys containing from 0 to 100% high fructose corn syrup (HFCS). δ13C values by both methods agreed within 0.2%o and gave an excellent straight line fit (slope = 0.991; R = 1). As an alternative to IRMS, ANCA-MS is automated and provides a 5-fold increase in sample throughput.
Multiresidue Matrix Solid Phase Dispersion (MSPD) Extraction and Gas Chromatographic Screening of Nine Chlorinated Pesticides in Catfish (Ictalurus punctatus) Muscle Tissue
Authors: Long Austin R , Crouch Michael D , Barker Steven A
Published: February 2020

A multiresidue technique for extraction and gas chromatographic screening of 9 insecticide (lindane, heptachlor, aldrin, heptachlor epoxide, p,p-DDE, dieldrin, endrin, p,p- TDE, and p,p'-DDT) residues In catfish {Ictalurus punctatus) muscle tissue is presented. The 9 Insecticides, plus dibutyl chlorendate internal standard, were fortified into catfish muscle tissue (0.5 g) and blended with 2 g C18 (octadecylsilyl derlvatized silica reverse-phase material). The C18/muscle tissue matrix blend was fashioned into a column by adding the blend to a 10 mL syringe barrel containing 2 g activated Florisil. The insecticides were then eluted from the column with acetonitrlle (8 mL), and a portion (2 μL) of the acetonitrile eluate was then directly analyzed by gas chromatography with electron capture detection. Unfortified blank controls were treated similarly. The resultant extracts contained pesticide analytes (31.25-500 ng/g) free of interfering compounds when analyzed. Correlation coefficients for the 9 extracted pesticide standard curves (linear regression analysis, n = 5) ranged from 0.9967 (± 0.0018) to 0.9999 (± 0.0001). Average percentage recoveries (82 ± 4.8% to 97 ± 3.6%, n = 25 for each Insecticide), Interassay (5.0 ± 2.7% to 16.9 ± 6.5%, n = 25 for each insecticide) and intraassay (1.8 to 4.7%, n = 5 for each Insecticide) variabilities were Indicative of an acceptable methodology for the analysis and screening of these residues in catfish muscle tissue.
Rapid Pentachlorophenol Evaluation in Solid Matrixes by Second Derivative UV Spectroscopy for Application to Wood and Leather Samples
Authors: Secchieri Monica , Benassi Carlo A , Pastore Saveria , Semenzato Alessandra , Bettero Antonio , Levorato Marco , Guerrato Alfredo
Published: February 2020

A method for the quali-quantltatlve evaluation of pentachlorophenol (PCP) in solid matrixes has been developed. The procedure Is based on solid-liquid extraction of solid samples (leather or wood), followed by purification on a cyanopropyl column and determination of the preservative by second derivative UV spectroscopy considering the PCP A peakthrough value (304-297 nm). The method allows rapid PCP determination In the concentration range 1-40 μg/mL; any matrix interference is avoided by the purification step and recoveries of the preservative were 99.12% (RSD% 0.13) for the leather matrix and 98.03 (RSD% 0.17) for the wood matrix.
Crude Oil Content of Selected Oilseeds and Flours: A Comparison of Solvents
Authors: Granata Gary , Lane Ralph H
Published: February 2020

A variety of wheat flours and ground oilseeds was subjected to continuous extraction for 6 h with each of 4 solvents (anhydrous diethyl ether, hexane, pentane, and petroleum ether). Hexane and diethyl ether were equally superior (P < 0.05) to the other 2 solvents In extracting crude oil from all-purpose flour and from ground peanuts, soybeans, cottonseeds, and canola seeds. Hexane yielded higher crude oil values (P < 0.05) than the other solvents in the case of ground safflower and sunflower seeds. Diethyl ether produced higher values (P < 0.05) from ground corn germ and bread flour. No differences (P < 0.05) were found among solvents when extracting whole wheat flour.
Performance Characteristics of Methods of Analysis Used for Regulatory Purposes.Part II. Pesticide Formulations
Authors: Horwttz William , Albert Richard
Published: February 2020

The precision parameters of the method-performance (collaborative) studies published In the AOAC Journal from 1915 through 1990 for pesticide formulations have been recalculated on a uniform basis by the International Union of Pure and Applied Chemistry 1987 protocol. About 93% of the 953 accepted assays, which are predominantly gravimetric (G), volumetric (V), and gas (GC) and liquid (LC) chromatographic methods, exhibit relative standard deviations among laboratories (RSDR) that are generally less than 2 times the values predicted from the Horwitz equation: RSDR (%) = 2 exp (1 - 0.5 log C), where C is the concentration expressed as a decimal fraction. UV, VIS, and IR spectrophotometrlc (S) methods are somewhat poorer, with about 80% of the reported RSDR values less than twice the predicted RSDR value. The precision parameters of pesticide formulations analyzed by the older methods (G, V, GC) are equivalent to those previously found for drug preparations in the same concentration range; the precision parameters of pesticide formulations analyzed by LC and S are somewhat poorer. Overall, however, the precision parameters of pesticide formulations are generally independent of analyte, method, and matrix, and are primarily a function of concentration. The method-acceptability decisions of the AOAC for pesticide formulations during the past 75 years can be approximated retrospectively by using a criterion for RSDR that is less than 2 times the RSDR calculated from the Horwitz equation.
Interlaboratory Assessment of Dry Calibration Milk Powders for Calibrating Infrared Milk Analyzers
Authors: Van De Voort Frederick R , Elkashef Abdel Aziz , Blais Jean-Simon
Published: February 2020

An interlaboratory study was carried out to assess the performance of preformulated, preanalyzed, dry calibration milk powders designed for calibrating infrared milk analyzers. The calibration powders can be reconstituted to produce consistent calibrations within laboratories. The powders met AOAC specifications In terms of accuracy and repeatability, and provide calibrations with performance characteristics comparable to those produced with conventional calibration milks. The reconstituted solutions were shown to be stable for up to 6 h at 40°C, and can be stored under refrigerated conditions and used for repeated analyses for up to 21 days without apparent deterioration In calibration performance. In general, the calibration powders perform as well as, or better than, the conventional calibrants used by the laboratories participating in the study, and the calibrations could be switched without significantly changing the analytical results. Simulation and cross-calibration analyses indicated that the powdered calibrants produced more consistent results overall than fluid calibration milks. The powdered calibrants, as formulated, are shown to be suitable for any application requiring calibrations that meet AOAC specifications, Including payment applications. The calibration powders have the stability and performance characteristics to serve as a consistent, stable reference standard for monitoring instrument performance, and would be a useful tool for Interlaboratory standardization or accrediting payment and dairy herd analysis laboratories.
Gas Chromatographic/Mass Spectrometric Determination of α-Methylstyrene in Styrene-Based Polymers and Food Simulants
Authors: Tan Shigeru , Tatsuno Takashi , Okada Taro
Published: February 2020

A selected ion monitoring method is described for the analysis of styrene (St)-based polymers for a-methylstyrene (α- MSt) and for determining the level of α-MSt migration from St-based sheets Into 4 food simulants. The polymers are dissolved in dlchloromethane; α-MSt Is determined by direct Injection of the polymer solutions. α-MSt migration from St-based sheet to water, 4% acetic acid, 20% ethanol, and n-heptane was measured by gas chromatography/mass spectrometry, using multiple ion monitoring of Ions at mix 118,78, and 91. α-MSt can be quantltated at levels as low as 10 μ/g in the polymer and 0.01 μ/g In the food simulants. Recoveries were 83-113% from St-based sheets and 90-99% from food simulants, respectively.
Near Infrared Reflectance Spectroscopy. Part II. Effect of Calibration Set Selection on Accuracy of Method
Authors: Barton Franklin E
Published: February 2020

Tall fescue samples (Festuca arundenacea Schreb) were collected during 1983-1985. The 1983 and 1984 samples were used for calibration and the 1985 samples were used for validation. The combined 1983-1984 calibration set contained 382 samples. The program "SUBSET" was run and 74 samples were selected. The remaining samples from 1983- 1984 were divided Into 4 files of 77 samples each by taking every 4th sample. The "SUBSET" program was run on the 1985 set of 211 samples and 40 samples were selected that represented all the spectral diversity in the set. Separate sets of equations were developed with 2 regression programs, "BEST" and "CAL," and used to predict acid detergent fiber, neutral detergent fiber, permanganate lignin, and crude protein. The results show that while a random selection could sometimes produce a better set for calibration, the "SUBSET" program picks a set that consistently will produce a good calibration. In most instances, the "SUBSET" equations were the best or next to the best when measured by the standard error of performance corrected for bias.
Quality Management (QA/QC) in the Analytical Laboratory
Authors: Schultz Mary G , Brown William L
Published: February 2020

An effective quality management system in the analytical laboratory must be designed to satisfy customers' needs and expectations while serving the laboratory's interests. An understanding of total quality and its components Is essential for the development of a quality management system In the analytical laboratory. Quality systems are founded on quality laboratory practices; they have a strong quality control component, and, more recently, monitoring through quality assurance. Development of a quality Improvement component with more emphasis on quality planning Is also needed to provide the necessary system for quality management
Fast Turnaround Multiresidue Screen for Pesticides in Produce
Authors: Hsu Jong P , Schattenberg Herbert J , Garza Martha M
Published: February 2020

A rapid multiresidue screen for 110 pesticides was applied to 5628 produce samples. Samples were extracted, analyzed, and evaluated within 6 1/2 h of receipt. Analyses were confirmed within a 24 h period on those samples in which a potential residue was found above the U.S. Environmental Protection Agency's tolerance level. A thorough yet quick chromatographic interpretation program is also described
Limited Survey of Residual Tetracyclines in Tissues Collected from Diseased Animals in Aichi Prefecture, Japan
Authors: Oka Hisao , Ikai Yoshitomo , Kawamura Norihisa , Hayakawa Junko
Published: February 2020

Tissues were collected to survey the actual conditions of tetracycline antibiotics (TCs) residues in slaughtered animals that did not pass inspection at slaughterhouses in Aichi Prefecture, Japan, because of the presence of disease symptoms. Tissues were analyzed by liquid chromatography. Among 271 samples, 49 (18.1%) were positive for oxytetracycline (OTC), 5 (1.8%) for chlortetracycline (CTC), and 5 (1.8%) for doxycyclfne (DC), respectively. One sample (cattle kidney) was positive for both OTC and DC. However, tetracycline was not detected in any samples. Percentage frequencies of TCs residues were 29.1% (37/127) and 15.2% (22/144) for cattle and hogs, respectively. Kidney samples showed higher incidence of TCs residues and 1.5-7 times higher residual concentrations than liver and miscellaneous samples.
Monitoring Aldehyde Production During Frying by Reversed-Phase Liquid Chromatography
Authors: Lane Ralph H , Smathers Janis L
Published: February 2020

Acrolein (2-propenal) and other low molecular weight aldehydes (LMWAs) formed by degradation of the frying medium (triglycerides) were monitored by liquid chromatography (LC) during preparation of fried items. LMWA contents of coatings from codfish and of doughnuts and their volatiles that codistill with steam are monitored by trapping the vapors and distillate from the food matrix in a 2,4-dinitrophenylhydrazine solution. The resulting hydrazones are partitioned from the aqueous phase, first into isooctane and then into acetonitrile for LC analysis. The hydrazones are separated and quantified on a C18 reversed-phase column with acetonitrile-water as the mobile phase. LMWAs are confirmed by gas chromatography/mass spectrometry. No difference was found in LMWA content in coatings from fish fillets fried at 182 or 204°C. Cake doughnuts were higher in acrolein content than yeast-raised doughnuts prepared under similar conditions. Freshness of the frying medium, frying time, and batch size did not seem to influence LMWA production from doughnuts. Results indicated that most of the LMWAs formed codistilled with steam during frying rather than remaining with the food item.
Improved Method for Determination of Polynuclear Aromatic Hydrocarbons in Pharmacopoeial Paraffin and Mineral Oils
Authors: Geahchan Aziz , Le Gren I , Chambon Paul , Chambon Renee
Published: February 2020

An improved method has been developed for quantitative determination of poiynuciear aromatic hydrocarbons (PAHs) in pharmacopoeial paraffin and medicinal white oil samples. This new method combines 2 liquid-liquid partition and adsorption chromatography procedures with a 2-step purification on Sephadex LH 20 and liquid chromatography with fluorometric determination. Selective elution of PAHs results in absence of background fluorescence. The minimum detectable level ranges from 0.2 ppt for benzofluoranthene isomers to 200 ppt for acenaphthene. Recoveries of PAHs added at 7 ppm varied from 92.1 to 111.4%. When a variety of medicinal white oil samples were analyzed by this improved method, 27 PAHs were identified, including 11 suspected carcinogens. Their identities were confirmed by capillary gas chromatography.
Multipesticide Determination in Surface Water by Gas Chromatography/Chemical Ionization/Mass Spectrometry/Ion Trap Detection
Authors: Mattern Gregory C , Louis Judith B , Rosen Joseph D
Published: February 2020

An improved method for the determination of trace levels of pesticides in surface water has been developed and was used to analyze 20 target pesticides in New Jersey. Pesticides were extracted from 2 L water samples, using a mixture of XAD-2 and XAD-7 resins, and were determined by gas chromatography/chemical ionization mass spectrometry with ion trap detection. Average recoveries (performed in triplicate at the 1 ppb level, except for captan and chlorothalonil at 5 ppb) were between 75 and 113%, with an average coefficient of variation of 9%. Most of the pesticides (alachlor, atrazine, butylate, carbofuran, chlorpyrifos, diazinon, fonofos, isofenphos, metolachlor, metribuzin, parathion, and simazine) had limits of detection (LODs) of 0.005 ppb or lower, while some (carbaryl, cyanazine, fenamiphos, linuron, pendlmethalin, and terbufos) had LODs between 0.005 and 0.05 ppb. Captan and chlorothalonil had LODs of 1 ppb. Of 31 samples analyzed, 29 contained one or more of the following pesticides: alachlor, atrazine, carbaryl, chlorpyrifos, cyanazine, diazinon, isofenphos, linuron, metolachlor, and simazine in concentrations between trace (<0.025 ppb) and 5.48 ppb.
Separation of Clethodim Herbicide from Acid and Photodegradation Products by Liquid Chromatography
Authors: Falb Linford N , Bridges David C , Smith Albert E
Published: February 2020

Clethodim, (E,E)-(±)-2-[1-[[(3-chloro-2-propenyl)oxy]lmino] propyl]-5[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one, is stable in acetonitrlie, but the Inclusion of water induced degradation in the dark. Addition of acetic acid to the mobile phase did not increase degradation; however, it did improve peak symmetry and liquid chromatographic (LC) separation, with the optimum resolution at 0.75% acetic acid. The extinction coefficient for clethodim at 254 nm did not change in acetonitrlie with addition of water or acetic acid. The LC detector responded linearly to clethodim in the 0.7-400 ppm range. Separate solvent gradient programs (40 min each) were developed for separation of acid degradation products (ADPs) and the photodegradation products (PDPs). The inclusion of cobalt or silver nitrate to the mobile phase did not improve separations. A minimum of 31 and 19 products formed during photolytic and hydrolytic degradation of clethodim, respectively. PDPs were more polar than ADPs. Reproducibility of this method was considered to be acceptable for separation of ADPs and PDPs of clethodim.
Determination of Ticarcillin and Clavulanic Acid in Serum by Liquid Chromatography
Authors: Wright Jennifer C , Durham Carl N , Dunbar Jacob R
Published: February 2020

A liquid chromatographic (LC) method using solidphase extraction for the determination of clavulanic acid and ticarcillin in human serum has been developed. Clavulanic acid and ticarcillin were extracted separately from 1 mL serum using C18 solid-phase extraction cartridges. Eluates were analyzed by the same reversed-phase LC system. The overall mean recovery of clavulanic acid from serum was 99.7 ±2.3%; the lowest level validated in serum was 0.5 μg/mL. The overall mean recovery of ticarcillin from serum was 101.5 ±3%; the lowest level validated in serum was 12.5 μg/mL. Detection limits for clavulanic acid and ticarcillin were 0.117 and 0.749 μg/mL, respectively.
Specification-Based Modified Control Limits in Quality Control of Trace Chemical Analyses
Authors: Grant C L , Mcgee I E , Jenkins T F , Stutz M H
Published: February 2020

Shewhart X and R charts were used to maintain and validate data quality of percent recovery estimates for 8 analytes determined by 4 procedures used routinely in 4 commercial laboratories over a 2-year period. However, because range (R) estimates of uncertainty did not Include lot-to-lot calibration variability, approximately 24% of the lots were "out-of-control." We extracted pooled standard deviations for So (repeatability within lot), SL (calibration variability), and SR (reproducibility), which represents the total variability. Values of So and SL were generally similar In size although there were some substantial differences between analytes and between laboratories for a given analyte. When control limits were based on reproducibility rather than repeatability, only about 6% of the lots were "out-of-control." However, these limits are less convenient to compute at the bench, wlthln-lot precision estimates are still required, and there Is still no Information on data acceptability. Capability estimates from the grand mean ±3 SR were surprisingly consistent for the 8 analytes. These values coupled with data quality objectives suggested the 82-115% range as the specifications for acceptable individual recoveries. A combination of repeatability limits plus modified limits anchored to specifications retains the simplicity of range computations while offering substantial administrative advantages. Examples are given to illustrate these points.
Liquid Chromatographic Determination
of Incurred Nitrofurazone Residues in Chicken Tissues
Authors: Parks Owen W , Kubena Leon F
Published: February 2020

One-day-old chicks were raised to maturity on a diet fortified with 0.0055% nitrofurazone. Analyses of tissue extracts by a liquid chromatography/electrochemlcal detection method revealed that the distribution of residues between liver, breast, and thigh muscle differed significantly from that previously reported In birds that were dosed with the drug before sacrifice. Differences between ground and unground tissues were also observed, suggesting that residues are not distributed evenly throughout the same tissue.
Extraction of Light Filth from Dried Bean Curd:
Collaborative Study
Authors: Nakashima Marvin J
Published: February 2020

Results are reported for a collaborative study of a method for the extraction of light filth from dried bean curd. A100 g test portion is dispersed in a 5.7% HCI solution. Residue from the No. 230 sieve is defatted In isopropanol, and the sieved residue is transferred to a Wildman trap flask. Light filth Is Isolated from 40% isopropanol by using Na4EDTA and mineral oil-heptane (70 + 30). Average recoveries by 6 collaborators for 3 spike levels of rat hairs (5,10, and 15) were 85,81, and 70%, respectively; for Insect fragments (5,15, and 30), recoveries were 72,83, and 72%, respectively. The method was adopted by AOAC International as first action.
Colorimetric Determination of Selenium
in Premixes and Supplements
Authors: Hurlbut Jeffrey A , Burkepile Roger G , Geisler Carolyn A
Published: February 2020

A colorimetric method Is described for the determination of 100-10 000 μg selenlum/g premix. Selenium Is present in premixes as either selenite or selenate. Moderate to high concentrations of several common minerals are tolerated. The premix is briefly digested In a sulfuric acid-perchloric acidsodium molybdate mixture, boiled in 10% NaCI solution, made basic, and centrifuged. Aliquots are taken if necessary. The mixture Is then acidified with formic acid, treated with hydroxylamlne hydrochlorlde- EDTA, and complexed with 3,3 - dlamlnobenzldlne. The pH Is adjusted, and an extraction Is performed with toluene. The absorbance is measured at 420 nm. Recoveries for 100- 10 000 μg selenlum/g premix ranged from 88 to 104%, with an average of 97%. The coefficient of variation ranged from 1.6 to 6.9%, with an average of 4.2%.
Determination of Monensin in Raw Material, Premix,
and Animal Feeds by Liquid Chromatography
with Correlation to Microbiological Assay
Authors: Rodewald J Matthew , Moran John W , Donoho Alvin L , Coleman Mark R
Published: February 2020

A method Is described for the detection and quantitation of monensin In raw material, premix, and feeds by liquid chromatography (LC) with postcolumn derlvatlzatlon with vanillin. Monensin was mixed with vanillin under acidic conditions and heated, and the resulting products were measured by a variable wavelength visible detector operating at 520 nm. The LC response of monensin and monensln-llke factors was determined and correlated to the microbiological response of each factor as determined with Streptococcus faeclum. Monensin reference standard was characterized In the same manner as the individual factors. The chemical composition of the reference standard and the relative microbiological potency values were used In combination to calculate the biopotency contribution of each of the monensin factors. A formula was used to transform chemical composition values of the reference standard to total microbiological activity as obtained directly from a microbiological assay. The formula was tested by comparing samples assayed by LC using the formula to report microbiological potency with samples assayed by the Autoturb method. Finally, the LC method was validated with raw material, premix, cattle rations (including liquid supplements), and poultry rations.
Automated Closed-System Headspace Determination
of Methyl Bromide in a Variety of Raw and Processed Nuts
Authors: Ford Joseph H , Legendre Michael G , Ladner Dorothy L , Dawson Joseph A , Raymond Caleph
Published: February 2020

An automatic gas chromatographic method was developed for determining methyl bromide residues In 11 different types of nuts. A 50 g sample Is placed In a modified stainless steel blender container and mixed with 200 mL 0.5M sodium sulfate. The blender container Is sealed with a screw lid, and the sample Is blended 3 min and equilibrated 17 mln in a bath-reclrculator at 26°C. The headspace gas Is automatically sampled and analyzed twice for methyl bromide residues. Recoveries are based on deviation from predetermined partitioning coefficients (p-values). The average p-values for the different nuts ranged from 0.28 to 0.43, and the CVs for their determinations ranged from 7.7 to 23.5%. The method Is sensitive, simple, and reproducible, and It is operated In a totally closed system. Over 1100 samples of assorted nuts were analyzed within a 6-month period
Fluorometric Determination of Thiamine Vitamers in Chicken
Authors: Fox Jay B , Ackerman Stanley A , Thayer Donald W
Published: February 2020

A comparison was made of the direct determination of thiamine In acidified heated chicken extracts, by either flow injection or chromatographic determination, with the standard method (acid and enzyme digestion, adsorption, and elutlon, followed by the fluorometric determination of thiochrome extracted by Isobutanol from K3Fe(CN)6-treated eluates). Liquid chromatography of extracts, followed by oxidation of thiamine vitamers to thlochromes, showed 1 light scatter emission peak and 2 thlochromes, the latter corresponding to thiamine and thiamine monophosphate. Both forms were determined quantitatively by flow Injection determination, the lower detection limit of which was about 60 femtomol. The determination was linear from 0.1 ng to 10 μg thlamlne/mL, and the pooled coefficient of variation was 4%. The determination of thiamine in chicken extracts provides a nondestructive method for determining thiamine and Its phosphate esters, either In toto by flow Injection determination or as individual components by chromatography.
Rapid Solvent-Efficient Method for Liquid Chromatographic Determination of Ochratoxin A in Corn, Barley, and Kidney: Collaborative Study
Authors: Nesheim Stanley , Stack Michael E , Trucksess Mary W , Eppley Robert M , Krogh Palle
Published: February 2020

A joint Interlaboratory study of a rapid, solvent-efficient liquid chromatographic method for determination of ochratoxin A (OTA) in barley, corn, and pork kidney tissue was conducted by AOAC, the International Union of Pure and Applied Chemistry, and the Nordic Committee on Food Analysis In 16 laboratories in Europe, Canada, and the United States. OTA was added to barley and corn at 10,20, and 50 ng/g and to kidney at 5,10, and 20 ng/g. Duplicate test portions were prepared at 20 ng/g for corn and barley and 10 ng/g for kidney. Mean recoveries of OTA ranged from 53 to 97%. Within-laboratory relative standard deviations were 7.9,20.1, and 15.7% for barley, corn, and kidney tissue, respectively. Between-laboratories relative standard deviations were 20.7-31.7% for all concentrations of OTA In barley and corn and 68.0,41.8, and 32.7% for OTA concentrations of 5,10, and 20 ng/g, respectively, In kidney. OTA Identity was confirmed by methyl ester derivatization followed by liquid chromatography. The method has been adopted first action by AOAC as quantitative at the levels tested for OTA determination In corn and barley.
Enzyme-Linked Immunosorbent Assay for Quantitation of Organophosphate Pesticides: Fenitrothion, Chlorpyrifos-methyl, and Pirimiphos-methyl in Wheat Grain and Flour-Milling Fractions
Authors: Skerritt John H , Hill Amanda S , Beasley Helen L , Edward Simone L , Mcadam David P
Published: February 2020

Simple, competitive enzyme-linked Immunosorbent assays (ELISAs) have been developed for the quantitation of each of 3 major organophosphate Insecticides: fenltrothlon (FN), chlorpyrifos-methyi (CPM), and plrlmlphos-methyl (PIRM). Performance of these assays on wheat grain and (for FN and CPM) on milling fractions such as flour, wheat germ, and bran has been assessed. Each assay is specific for the particular compound, i.e., no significant cross-reaction with the other 2 pesticides is observed. Only limited reactions were noted with major metabolites or analogs of these pesticides. Assay limits of detection of 0.3 ng FN, 0.2 ng CPM, and 0.02 ng PIRM, corresponding to limits of detection in whole grain of 0.08 ppm FN, 0.2 ppm CPM, and 0.03 ppm PIRM. Each compound In grain and milling fractions could be extracted quantitatively by simple shaking in neat methanol. Multiresidue analysis of the 3 insecticides was performed by simultaneously adding the cereal extract (diluted in phosphate buffer) to separate duplicate microwells coated with antibodies to FN, CPM, and PIRM and adding appropriate pesticide-horseradish peroxidase conjugates. High correlations between gas chromatography and the ELISA methods were obtained for Insecticide levels In whole wheat and In milling fractions. In general, the ELISA assays had precision similar to those of instrumental pesticide analyses.
Rapid Whole-Blood Cholinesterase Assay with Potential Use for Biological Monitoring During Chemical Weapons Disposal
Authors: Halbrook Richard S , Guzman Carmen E , Wilkinson Karen J , Watson Annetta P , Munro Nancy B , Shugart Lee R
Published: February 2020

A protocol Is described to determine whole-blood cholinesterase activity using an automated highspeed centrifugal analyzer. Throughput rate was increased 10-fold (from 6 to 60 samples/h), and precision, as measured by a reduction In Intra-allquot variation, was significantly Improved (from 4.7 to 3.0%) by using an automated system rather than a manual system. Similar cholinesterase activity was determined for samples analyzed by both the automated and manual protocols, and Interlaboratory comparison Indicated no change In accuracy. The lower limit of detection was estimated to be 0.10 μmol/mL/mln. The 10-fold Increase In throughput facilitates use of the automated protocol when many analyses must be performed in a limited time.