bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas-Liquid Chromatographic Determination of S,S,S-Tributyl Phosphorotrithioate (DEF) in Water and Fish Tissue
Authors: Lehmann R G , Smith L M , Wiedmeyer R H , Petty J D
Published: February 2020

Methods are described for determination of S,S,S-tributylphosphorotrithioate (DEF) at levels as low as 5 parts per billion in fish and 200 parts per trillion in water. Fish tissue extracts are subjected to gel permeation chromatography (GPC) and silica gel chromatography; water samples are extracted with dichloromethane. Analyses are carried out by gas chromatography in which either electron capture or thermionic specific detectors are used. The applicability of the methods is demonstrated by analyses of water and fish samples from exposure studies
High Resolution Gas Chromatography of Chlorinated Benzenes
Authors: Miller Lee J , Farrell Terryl J , Puma Bart J
Published: February 2020

Chlorinated benzenes have been found as contaminants in foods and water. These high production volume chemicals may enter the environment and food chain through improper waste disposal, use as solvents and odor control agents, or as impurities in other industrial chemicals. Because of differences in the electron capture responses of the isomers at each chlorination level, residue quantitation requires the separation of all 12 chlorobenzenes. Resolution studies were made on packed and capillary columns coated with Kovats’ C87H176 hydrocarbon, OV-101, OV-210, OV-17, and Carbowax 20M. Satisfactory resolution of all 12 chlorobenzenes was obtained with a Carbowax 20M-coated 20 m × 0.25 mm id capillary column operated isothermally at 120°C.
Portable Micro Method for Quantitative Determination of Vitamin C in Fruit and Vegetable Juices
Authors: Rymal Kenneth S
Published: February 2020

A portable rapid and accurate micro method is described for the quantitative determination of vitamin C in fruit and vegetable juices. Chromatographic paper is impregnated with DCP by immersion in 95% ethanol solution and sprayed with a protective starch solution. Papers are usable indefinitely when protected from moisture, light, air, and high temperatures. Determinations can be completed in 60 s with an accuracy of ±2.0 mg/100 mL fruit or vegetable juice. Cloudy or lightly colored samples do not interfere with the determination. The method was compared with the official AOAC 2,6-dichloroindophenol (DCP) titration method and gave a linear correlation coefficient of 0.99749.
Simple, Sensitive Technique for Detection and Separation of Halogenated Synthetic Pyrethroids by Thin Layer Chromatography
Authors: Sundararajan Radhakrishnan , Chawla Ram Parkash
Published: February 2020

Thin layer chromatography employing silver nitrate-impregnated alumina G plates has been extended for the routine detection and confirmation of the identity of halogenated synthetic pyrethroid insecticides. Of the solvent systems tried, maximum resolution was achieved by using n-hexane-benzene (45+ 55) and n-hexane-chloroform (60 + 40), which gave distinct separations of the cis- and trans-isomers of permethrin and cypermethrin from fenvalerate and decamethrin. Possible interference of HCH isomers and DDT and its analogs can also be checked by a concurrent run of the sample mixture in these 2 systems. A minimum of 50 ng each of cis- and trans-permethrin and cypermethrin isomers and fenvalerate and decamethrin can be positively detected. Using this technique, the minimum detectable limit of permethrin was 0.1 ppm in the cleaned up extracts of tomato plant and fruit and soil samples.
pplicability of a Multiresidue Method and High Performance Liquid Chromatography for Determining Quinomethionate in Apples and Oranges
Authors: Krause Richard T , August E Michael
Published: February 2020

The AOAC multiresidue method for nonpolar pesticide residues in nonfatty foods has been coupled with a high performance liquid chromatographic (HPLC)-fluorometric system for determining quinomethionate residues on apples and oranges. Quinomethionate is extracted with acetonitrile, and coextractives are removed with liquid-liquid partitioning and Florisil adsorbent using the AOAC multipesticide residue method for nonfatty foods. The quinomethionate fraction is then chromatographed on an HPLC octyl-bonded column and detected in-line with a fluorescence detector using 362 nm excitation and 395 nm emission. Recovery studies were conducted with apples fortified with quinomethionate at 0.05 ppm and oranges at 0.05 and 0.5 ppm. The recoveries averaged 100% (range 92-108) at the 0.05 ppm fortification level and 102% (range 93-110) at the 0.5 ppm level.
Analysis of Pesticide Residues by Chemical Derivatization. VI. Analysis of Ten Acid Herbicides in Sediment1
Authors: Lee Hing-Biu , Chau Alfred S Y
Published: February 2020

A sensitive gas-liquid chromatographic (GLC) method was developed for multiresidue analysis of 10 acid herbicides in sediment. An acidified sediment sample was extracted 3 times with acetonehexane. The combined organic extract was partitioned with acidified water to remove aqueous coextractives. To produce low detection limits for all herbicides including MCPA and MCPB for routine monitoring purposes, pentaf luorobenzyl esters were formed before GLC analysis. Recoveries of all herbicides from fortified sediment samples were better than 80% at the levels studied. Practical detection limits of this method were 10-25 μg/kg (ppb).
Mojonnier Method as Reference for Infrared Determination of Fat in Meat Products
Authors: MILLS Bernice L , Voort F R Van De , Usborne W R
Published: February 2020

The Mojonnier method was compared with the conventional Soxhlet method for the determination of fat in 7 different meat products to assess its use as a standard reference method for calibration of commercial quantitative infrared transmission analyzers (e.g., Multispec M, Milkoscan 300 or 104). Results for the meat samples obtained by the Mojonnier method did not differ significantly from those obtained by the Soxhlet method. In addition, the Mojonnier method was less time-consuming and more precise than the Soxhlet; therefore, it can be used as a standard reference procedure for the calibration and assessment of infrared milk analyzers in their potential application to the rapid determination of fat in meat and meat products.
Gas-Liquid Chromatographic Determination of Sucrose Fatty Acid Esters
Authors: Tsuda Taizo , Nakanishi Hiroshi
Published: February 2020

A method was developed for gas-liquid chromatographic determination of sucrose fatty acid esters as TMS derivative of sucrose and methyl esters of fatty acids. Sucrose fatty acid esters were completely degraded to sucrose and fatty acids in alkaline ethanol overnight at 25°C. Sucrose was derivatized with pyridine, trimethylchlorosilane, and N-trimethylsilylimidazole and the sucrose TMS derivative was determined on a 2% OV-17 column. Fatty acids were extracted with ethyl ether, methylated with BF3-methanol complex at 65°C, and determined on a 2% DEGS + 0.5% H3PO4 column. This method was applied to selected sucrose fatty acid esters. For example, sucrose and fatty acids derived from 50 mg sample F20 were 10.6-11.0 and 38.1-39.0 mg, respectively. Total amounts were 48.7-50.0 mg with a standard deviation of 0.4 (n = 6).
Rapid High Pressure Liquid Chromatographic Determination of Anatoxin M1 in Milk and Nonfat Dry Milk
Authors: Chang Henry L , DeVries Jonathan W
Published: February 2020

A modification of the current revised AOAC method, 26.A10-26.A15, is described for the rapid analysis of aflatoxin Mi in milk and nonfat dry milk. The method incorporates chloroform extraction and eliminates the need for column chromatography by using liquid-liquid partition for sample extract cleanup. Quantitation is carried out by using fluorescence detection combined with high pressure liquid chromatography (HPLC) of aflatoxin M1 which has been converted to aflatoxin M2a with trifluoroacetic acid. The method has a detection limit of 0.014μg/L (2 X signal/noise) for whole milk. For 6 samples of naturally contaminated nonfat dry and fteeze-dried milk, the modified method gave an average result of 0.698 μg/L; the AOAC method gave an average result of 0.386 μg/L.
Nonaqueous Reverse Phase Liquid Chromatographic Determination of Vitamin D2 in Multivitamin Tablets, Using Vitamin D3 as Internal Standard
Authors: Fong Godwin W K , Johnson Raymond N , Kho Boen T
Published: February 2020

The technique of nonaqueous reverse phase chromatography has been successfully applied to the separation of lipophilic vitamins D2 and D3. Separation is achieved with a Zorbax-ODS column and a mobile phase of 10% methanol in acetonitrile. A predetermined amount of vitamin D3 internal standard is added to a portion of a powdered tablet sample, which is then extracted and partitioned with a mixture of dimethyl sulfoxide, water, methanol, and hexane. A portion of the hexane extract is concentrated, and purified by passing it through a disposable silica cartridge to remove interfering materials. The method should also be applicable to formulations containing vitamin D3 where vitamin D2 can then be used as the internal standard. A system suitability test is included in the method.
Evaluation of Potential Analytical Approach for Determination of Polychlorinated Biphenyls in Serum: Interlaboratory Study
Authors: Burse Virlyn W , Needham Larry L , Lapeza Chester R , Korver Margaret P , Liddle John A , Bayse David D
Published: February 2020

Forty-four laboratories participated in evaluation of a method for determining polychlorinated biphenyls (PCBs) as AR 1254 in serum at the parts per billion level. The method involves deproteinating serum with methanol, extracting with hexane-ethyl ether, and eluting PCBs from deactivated silica gel for gasliquid chromatographic determination with electron capture detection. Compounds are quantitated by using the Webb-McCall factors. Five serum pools, 4 containing in vivo-fortified PCBs (as AR 1254) or 8 in vitro-f ortif ied chlorinated hydrocarbons (CHs), or both, were used. For PCB fortification levels of 9.89 (EP 2), 24.74 (EP 3), and 74.20 ppb (EP 4), interlaboratory coefficients of variation (CVs) for collaborators that adhered to protocol were 92.7, 67.6, and 25.8%, respectively. CVs on the same pools analyzed by the Centers for Disease Control (CDC) were 7.4, 7.8, and 4.6%, respectively. Average interlaboratory recoveries for pools EP 2, EP 3, and EP 4 were 138.1,111.2, and 91.1%, respectively, and 99.8,89.6, and 90.4%, respectively, for CDC on the same pools. There was a general decrease in the mean error for those laboratories that had participated in an earlier study in which they were allowed to use their own methods.
Determination of Acrylonitrile in Foods by Headspace Gas-Liquid Chromatography with Nitrogen-Phosphorus Detection
Authors: Page B Denis , Charbonneau Claudette F
Published: February 2020

A general procedure is described for the determination of acrylonitrile (AN) in foods such as margarine, honey butter, cold-pack cheese, and peanut butter, which are likely to be packaged in AN-based plastic. The entire sample is blended with water and salt at <5°C, aliquots are sealed in crimp-top vials, and the vials are equilibrated in a boiling water bath. The headspace is sampled by using a heated syringe, and AN is determined by gas chromatography with a nitrogen- phosphorus selective detector. The inclusion of propionitrile as an internal standard allows quantitation of AN with detection at 4,4, and 10 ppb for margarine, honey butter, and cold-pack cheese, respectively. A peak corresponding to about 5 ppb apparent AN in all non-AN-packaged peanut butter samples examined limits detection in peanut butter to about 15 ppb. The coefficients of variation at 20 ppb for margarine, honey butter, cold-pack cheese, and peanut butter were 7.5, 8.3, 7.3, and 10.2%, respectively.
Filament Hygrometer for Water Activity Measurement: Interlaboratory Evaluation
Authors: Jakobsen Mogens
Published: February 2020

A method is presented for measuring water activity (aw) of foods with a filament hygrometer. An interlaboratory evaluation carried out for the Nordic Committee on Food Analysis demonstrated that measurements can be made with a repeatability and reproducibility of 0.005 and 0.010 aw, respectively. The critical parameters of aw measurements are defined and discussed in relation to the accuracy and reproducibility required. The need for strictly standardized procedures for maintenance of the equipment, sample treatment, calibration, and measuring is emphasized.
Comparison of Iron Milk and Official AOAC Methods for Enumeration of Clostridium perfringens from Fresh Seafoods
Authors: Abeyta Carlos
Published: February 2020

Fresh seafoods collected from Seattle area markets were evaluated for the presence and numbers of Clostridium perfringens. In a comparison of the official AOAC Shahidi-Ferguson perfringens and the simple iron milk methods, 29 of 287 samples of fresh fish and shellfish were positive for C. perfringens. All 29 positive samples were detected by the iron milk medium; however, only 7 of the 29 were detected by the AOAC methods. A statistical evaluation of the data showed a significant difference between the 2 methods
Liquid Chromatography of Liquid Formulations Containing 2,4-Dichlorophenoxyacetic Acid, Dicamba, and 2-(2-Methyl-4-chlorophenoxy)propionic Acid as Their Salts
Authors: Grorud Robert B , Forrette John E
Published: February 2020

A high pressure liquid chromatographic method has been developed for liquid herbicide combinations that contain different combinations of 3 active ingredients including 2,4-dichlorophenoxyacetic acid (2,4-D), 2-(2-methyl-4-chlorophenoxy)propionic acid (MCPP), and dicamba. A reverse phase column in the ion suppression mode and a binary solvent system separate all 3 herbicides quantitatively on a single chromatogram. The internal standard solution may contain 2 internal standards, salicylic acid and butyrophenone, for use with certain combinations of the herbicides. The solvent system resolves the compounds of interest from all significant impurities.
Composition of Apple Juice
Authors: Mattick Leonard R , Moyer James C
Published: February 2020

Thirty-one samples from 8 geographic growing regions of the United States and 15 varieties common to these areas were converted to apple juice and analyzed for their attributes over the 3 year period 1979, 1980, and 1981. The total of 93 samples were analyzed for ash, brix, pH, proline, specific gravity, total acid, sorbitol, sucrose, fructose, and glucose. The elements cadmium, calcium, iron, lead, phosphorus, potassium, sodium, and zinc were also determined. These data are presented to serve as a data base for the detection of fraudulent or adulterated apple juice.
Gas Chromatographic Determination of Maleic Hydrazide Residues in Potato Tubers
Authors: King Russell R
Published: February 2020

A gas chromatographic (GC) method is described for the determination of maleic hydrazide residues in potato tubers by oxidation of maleic hydrazide with aqueous lead dioxide to 3,6-pyridazinedione in the presence of cyclopentadiene. The reaction product, i volatile Diels-Alder adduct, could be detected in potatoes at levels in excess of 0.05 ppm with an electron capture detector. Recoveries of maleic hydrazide (as the Diels-Alder adduct) from potatoes at fortification levels of 0.1 to 10 ppm averaged 91.7%.
Interlaboratory Study of the Hall 700A Halogen Electrolytic Conductivity Gas Chromatographic Detector
Authors: Carson Louis J
Published: February 2020

An interlaboratory study of the Hall 700A (halogen) electrolytic conductivity GC detector was carried out in 8 Food and Drug Administration laboratories. The study sought to provide data to support the use of the Hall 700A (halogen) detector as an alternative to the electron capture and microcoulometer detectors in the determination of pesticide and industrial chemical residues. The following characteristics of the detector were studied: linear dynamic range for 12 organohalogen pesticides and industrial chemicals injected over a 0.05-27.00 μg/mL range; repeatability of response; quantitation of 5 pesticides and Aroclor 1254 added to food extracts (fish and green peppers) cleaned up by commonly used multiresidue analytical methods; selectivity, defined as response to a halogenated compound (chlorpyrifos) vs response to a nonhalogenated compound (caffeine). The interlaboratory study showed that halogen response and selectivity are independent factors which define the performance of the Hall 700A (halogen) detector. Recommendations are provided to ensure consistent and selective halogen response. Finally, the study provides adequate data to support continued use of the Hall 700A (halogen) detector in the determination, of pesticides and industrial chemicals.
Determination of Coumaphos and Its Oxygen Analog in Eggs and Milk by Using a Multiresidue Method with Liquid Chromatographic Quantitation and Capillary Gas Chromatographic/Mass Spectrometric Confirmation
Authors: Krause Richard T , Min Zhao , Shotkin Sharona H
Published: February 2020

A multiresidue method for carbamate insecticides was adapted for the determination of coumaphos and its oxygen analog in eggs and milk. Eggs were extracted with acetonitrile and milk was extracted with acetone. Co-extractives were removed using liquid partitioning and charcoal column procedures described in the carbamate method. Coumaphos and its oxygen analog were determined by using a high performance liquid chromatograph equipped with a fluorescence detector. Recovery studies were performed for the 2 compounds at levels of 0.01 and 0.10 ppm in eggs and 0.01 and 0.02 ppm in milk. Overall average recovery was 100% (range 95-109%). In a trial of the method by another laboratory, the recovery of coumaphos and its oxygen analog from milk averaged 87 and 96%, respectively. Data are presented on the capillary gas chromatographic/mass spectrometric confirmation of coumaphos residues.
Simultaneous Spectrophotometric Determination of Amodiaquine-Primaquine Mixtures in Dosage Forms
Authors: Hassan Sayed M , Metwally Mohammed E-S , Malek A Abdel
Published: February 2020

Using 0.1N hydrochloric acid as solvent, mixtures of amodiaquine and primaquine have been measured at 282 and 342 nm. The concentration of each can then be calculated by solving 2 simultaneous equations. Excellent recoveries from authentic samples were obtained and the method proved suitable for routine analysis.
Rapid Detection of Fusarium Mycotoxins in Grains by Quadrupole Mass Spectrometry/Mass Spectrometry
Authors: Plattner Ronald D , Bennett Glenn A
Published: February 2020

The Fusarium mycotoxins deoxynivalenol (DON) and zearalenone can be detected rapidly in a crude extract of a grain matrix by quadrupole mass spectrometry/ mass spectrometric analysis of the collisionally activated dissociation (CAD) daughter fragments of the protonated molecule. Detection limits were as low as 0.1 ppm. The 2 toxins were detected in a single analysis. Monitoring the CATJ daughters of the negative ion m/z 248 of DON eliminated most interferences from the grain matrix and produced daughter spectra identical to those produced from an authentic standard.
Gas Chromatographic Determination of Deoxynivalenol in Wheat
Authors: Bennett Glenn A , Stubblefield Robert D , Shannon Gail M , Shotwell Odette L
Published: February 2020

Modifications to a published method are described for the determination of deoxynivalenol (DON) in wheat by gas chromatography with electron capture quantitation of the heptafluorobutyrate derivative. In the modified method, DON is extracted by shaking the sample with methanol-water on a wrist-action shaker, followed by filtration through rapid flow paper. One concentration step is eliminated, and a hexane wash is incorporated to remove toluene from the silica gel column. Recoveries of DON from wheat samples spiked at 0.1,0.5, and 1.0 ppm ranged from 77.3 to 86.3% and averaged 81.5%.
Survey of Baby Bottle Rubber Nipples for Volatile N-Nitrosamines
Authors: Havery Donald C , Fazio Thomas
Published: February 2020

A local market survey of 27 baby bottle rubber nipples for volatile N-nitrosamines was conducted. N-Nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodibutylamine, and N-nitrosopiperidine were found at levels up to 387 ppb. All 4 nitrosamines migrated from the rubber nipples into water, milk, and infant formula when sterilized together in a manner typical of that used in the home. The source of the nitrosamines is the chemical accelerators and stabilizers added to raw rubber during the vulcanization process.
Improved Cleanup and Derivatization for Gas Chromatographic Determination of Monosodium Glutamate in Foods
Authors: Nakanishi Hiroshi
Published: February 2020

A gas chromatographic procedure is described for determining monosodium glutamate (MSG) in several types of food. A sample is extracted with acetone- water (1 + 1). Acetone is evaporated and an aliquot of the extract is buffered with 1M NH4OH-1M NH4CI pH 9 solution, and chromatographed directly on a column of QAE Sephadex A-25 that has been pretreated with the same buffer. MSG is eluted with 0.1N HC1, and a portion of the eluate is evaporated to dryness and reacted with dimethylformamide( DMF)-dimethylacetal to form the glutamic acid derivative, which is injected into a gas chromatograph and measured by flame ionization detection. Recoveries of MSG from sample fortified at 5-500 mg ranged from 92.8 to 100%.
Pesticide Residue Levels in Foods in the United States from July 1,1969, to June 30,1976: Summary
Authors: Duggan Reo E , Corneliussen Paul E , Duggan Mary B , Mcmahon Bernadette M , Martin Robert J
Published: February 2020

The U.S. food supply was examined for pesticide residues during the 7-year period covering Fiscal Years (FY) 1970 through 1976. The results, which are contained in the report summarized here, are a continuation of an earlier report for the 6-year period FY 1964-1969.
Validated Extraction and Cleanup Procedures for Polychlorinated Biphenyls and DDE in Human Body Fluids and Infant Formula
Authors: Mckinney Lois Moore James D , Prokopetz Andrew , Walters Douglas B
Published: February 2020

As part of an epidemiology study, extraction methods and extract cleanup procedures were developed and validated for polychlorinated biphenyls (PCBs) and DDE, an ubiquitous metabolite of DDT, in human milk, blood serum, and infant formula. Studies included quantitative and reproducible recovery of total lipids, and reproducible and reasonably high recoveries of these chlorinated compounds from the human body fluids and infant formula, including levels of environmental health interest. An extensive quality control and assurance program was designed for use with these methods. Some validation work on serum was done using radiolabeled 14C-Aroclor 1254. Dilution assays were developed to permit use of a constant procedure, which should minimize variability in results. Methods are based on selected organic solvent extraction and column chromatographic cleanup techniques and quantitation by electron capture gas chromatography (EC/GC). Using these extensively researched extraction and cleanup methods, the limits of detection for GC measurements were 10.0 and 2.00 ppb for PCBs and DDE, respectively, in milk and 4.00 and 0.80 ppb in serum.
Liquid Chromatographic Separation and Fluorometric Determination of Quaternium-15 in Cosmetics
Authors: Stack Ann R , Davis Henry M
Published: February 2020

A method is described for the determination of the cosmetic preservative quaternium-15 (cis-l-(3-chIoroallyl)-3,5,7-triaza-l-azoniaadamantane chloride) in the presence of free formaldehyde, 2-bromo-2- nitro-l,3-propanediol, and imidazolidinyl urea. Quaterium-15 is separated from the other preservatives in cosmetic products by using liquid chromatography on a pellicular reverse phase C18 column. Formaldehyde released from the eluted quaternium-15 reacts with ammonium acetate-buffered 2,4-pentanedione reagent in a heated reaction coil to form the highly fluorescent post-column derivative 3,5-diacetyl-l,4-dihydrolutidine. A minimum of 1 μg quaternium-15/mL (0.001%) is detected by fluorescence. Recoveries of quaternium-15 from samples of a lotion, a body detergent, and a mascara spiked at 0.01, 0.1, and 0.2% ranged from 94 to 106% and averaged 100%.
Determination of Cyanogenic Glycoside in Seeds by Molecular Absorption Spectrometry in the Gas Phase
Authors: Kupchella Lawrence , Syty Augusta
Published: February 2020

As a means of evaluating cyanogenic glycoside content, cyanide was determined in apple, cherry, almond, and peach seeds. Sample preparation involved enzymatic hydrolysis and collection of hydrogen cyanide in strong base. For analysis, cyanide was converted to ammonium by addition of excess KMn04 followed by treatment with H2S04, and the resulting NH4+ was determined by the novel gas-phase molecular absorption spectrometric technique. An atomic absorption spectrophotometer, with a flow-through absorption cell replacing the flame, was used in the analysis. Recovery of amygdalin was 98.4 ± 1.2% complete. Cyanogenic glycoside contents determined in seeds (0.93% for apple, 2.05% for cherry, 2.43% for peach, and 0.00% for almond, reported in terms of amygdalin), were confirmed by a standard titration method. The lowest detectable concentration was 0.2 μg NH4+/mL, which corresponds to a detection limit of 0.5 mg amygdalin in the seed sample.
Analyst Performance with Aflatoxin Methods as Determined from AOCS Smalley Check Sample Program: Short-Term and Long-Term Views
Authors: Mckinney John D
Published: February 2020

The International Smalley Aflatoxin Check Sample Program of the American Oil Chemists' Society has offered check sample series for aflatoxins in peanut meal, cottonseed meal, and corn meal since 1976, and an aflatoxin M in raw milk series since 1980. This paper provides the computed mean of all analysts' results and between-laboratory precision for each of the samples in each of the check sample series distributed in 1980–81 and 1981–82. In addition, a comparison is made of the relative measurement and analytical accuracy of those analysts who have participated in the peanut meal series for at least 4 years and in the cottonseed and corn meal series since their inception (6 years). For this comparison, each analyst's result for each sample was calculated as a percent of the mean for all analysts for that sample; these values were then averaged for each analyst over all the meal samples in all the series for each meal type in which the analyst had participated, to obtain an overall measure of analytical accuracy. A similar calculation was made using the reported results for the defined solution of anatoxins included in each series, to obtain an overall measure of measurement accuracy. An evaluation of the meal series results for the past 2 seasons shows an overall within-laboratory precision in the range reported for the collaborative studies by which the methods were validated; the between-laboratory precision, although improved over past years, is still far from the collaborative study range. The precision data for the aflatoxin solution included in each series indicate this bias could be related, in large part, to the reference standards used. The extended period evaluation of analysts' performance shows no apparent correlation between measurement and analytical accuracy except for a general positive trend for those analysts using the BF method for anatoxins in peanut meal. A comparison of the accuracy of the BF and CB methods for aflatoxins in peanut meal shows no significant difference between results by the 2 methods on the basis of the extended period evaluation, in contrast to the generally higher results for the CB method in the past 2 seasons' evaluation. The scatter in the average analysts' analytical accuracy is essentially the same, regardless of the method used.
Preparation of Deoxynivalenol (Vomitoxin) from Field-Inoculated Corn
Authors: Scott Peter M , Lawrence Guillaume A , Telli Arvind , Iyengar Jagannath R
Published: February 2020

A process was developed for production of gram quantities of deoxynivalenol (DON) from corn that had been inoculated in the field with Fusarium graminearum and was estimated to contain 400–500 mg DON/kg. Steps in the purification procedure included extraction with methanol–water (1 + 1), partition from an aqueous solution into ethyl acetate by using a hydrophilic matrix, defatting, Florisil column chromatography, methylene chloride-water partition, semipreparative liquid chromatography (LC), and crystallization from ethyl acetate. The average yield of crystalline DON produced by this method (or with minor variations) was 281 mg/kg.
Comparison of Three Methods for Determination of N-NitrosopyrroIidine in Fried Dry-Cured Bacon
Authors: Gates Robert A , Pensabene John W , Walter Fiddler
Published: February 2020

The recently developed Eastern Regional Research Center (ERRC) dry column chromatographic procedure for determining A'-nitrosopyrrolidine (NPYR) in fried cure-pumped bacon was evaluated for its applicability to fried dry-cured bacon. The method was then compared with 2 established procedures for volatile nitrosamine analysis in cured meat products: the multidetection thermal energy analyzer (MD) method and the mineral oil distillation (MOD) screening procedure. No significant difference (P < 0.05) in NPYR values was found between the ERRC and MD procedures, but significant differences were found between the ERRC and MOD procedures and between the MOD and MD procedures. No artifactual nitrosamine formation was found in the ERRC procedure, but significant amounts were found in samples analyzed by the MOD procedure. The ERRC method was demonstrated to be rugged and very rapid. It is proposed that the ERRC method replace the MOD method as the official screening procedure for NPYR in fried bacon.
Titrimetric Determination of Ascorbic Acid Using Chloranil
Authors: Verma Krishna K , Jain Archana , Rawat Rameshwar
Published: February 2020

Ascorbic acid is oxidized and quantitatively titrated with chloranil (2,3,5,6-tetrachloro-l,4-benzoquinone) in the presence of hexamethylenetetramine in acetone-water; the end point is determined visually by the appearance of a golden yellow color. Colored solutions are assayed by setting the initial absorbance at 451 nm to zero or the minimum, titrating with chloranil solution, and measuring absorbance after each increment of titrant. A plot of the volume of chloranil added against the absorbance gives a straight line with the volume intercept as the end point. Interference by the thiol group of cysteine, glutathione, etc., is avoided by masking with acrylamide; interference by iron(II) is masked with ammonium thiocyanate and sodium potassium tartrate. Hydrogen sulfite and thiourea (which do not interfere) are added as antioxidants during extraction of ascorbic acid from drugs and fruits.
Liquid Chromatographic and Ultraviolet Spectrophotometric Determination of Bevantolol and Hydrochlorothiazide in Feeds
Authors: Spurlock Carola H , Schneider Horst G
Published: February 2020

Separate assay methods have been developed for the 2 components of an SO + 20 drug blend of bevantolol and hydrochlorothiazide (HCT) in admixtures with animal feed. Drug/diet admixtures are extracted with methanol for reverse phase ion-pair liquid chromatographic (LC) assay of bevantolol, and with acetonitrile for ultraviolet spectrophotometric assay of HCT. Bevantolol, a cardioselective beta blocker, is separated from soluble feed components with an RP-18 column, using methanol–water–acetic acid (60 + 40 + 1) containing 0.005M octanesulfonic acid, sodium salt, as ion-pairing reagent. HCT is determined spectrophotometrically in acetonitrile extracts, using a suitable blank extract as reference. Average recovery of HCT from an admixture of 0.5 mg blend/g diet is 94.5% ± 4.3 RSD and at 2.0 mg/g, 101.5% ± 3.5 RSD. Bevantolol recovery from the same admixtures is 101.8% ± 2.7 RSD and 99.0% ± 3.5 RSD, respectively, using the method as described.
Modification of Liquid Chromatographic Method for Analysis of Rotenone Formulations
Authors: Bushway Rodney J
Published: February 2020

Modifications have been made on the official first action liquid chromatographic method for analysis of rotenone formulations. Methanol–water was replaced with acetonitrile–water as the eluant and methanol was substituted for dioxane as the extracting solvent. The extraction procedure has been changed from 1½ h of rotary shaking to 5 min of sonication. The rest of the procedure is identical to the published method. For 9 different products analyzed 6 times each, the percent coefficients of variation were all below 2.40. Five of these 9 samples were previously used in the rotenone collaborative study. A comparison of results from both studies showed that the modifications did not affect the percent rotenone found. It is recommended that these changes be tested in a mini-collaborative study.
Near Infrared Reflectance Spectroscopic Determination of Protein Nitrogen in Plant Tissue
Authors: Isaac Robert A , Johnson William C
Published: February 2020

A rapid, nondestructive method is described for the determination of protein nitrogen in plant tissue, using near infrared reflectance (NIR) spectroscopy. Procedures for instrument calibration are discussed. Comparisons between Kjeldahl nitrogen and NIR nitrogen are made for corn leaf tissue from Georgia and Indiana. Multiple correlation coefficients for other plant tissues such as peanuts, soybean, wheat, pecan, bermuda grass, and bent grass are also shown.
Liquid Chromatographic Determination of Aspartame in Dry Beverage Bases and Sweetener Tablets with Confirmation by Thin Layer Chromatography
Authors: Daniels Daniel H , Joe Frank L , Warner Charles R , Fazio Thomas
Published: February 2020

A liquid chromatographic method is described for the determination of aspartame in dry beverage bases and sweetener tablets. The sample was mixed with the mobile phase, the pH was adjusted to within ±0.1 pH unit of the mobile phase, and the sample was diluted to volume with the mobile phase. The solution was Altered and a 10 μL aliquot was injected onto a C18 reverse phase column. Aspartame was quantitated with an ultraviolet detector. Recoveries of aspartame ranged from 94 to 111%. The dry beverage bases contained 5–13% aspartame and the sweetener tablets contained 19% aspartame. The presence of aspartame was confirmed by using thin layer chromatography.
Determination of Residual Levels and Migration of Benzene from Styrene-Containing Polymers
Authors: Varner Sandra L
Published: February 2020

Styrene-based food-contact polymers were examined for the presence and migration of residual benzene. Headspace gas chromatography (GC) with a column of 20% SP 2100–0.1% Carbowax 1500 on Supelcoport and a flame ionization detector were used for quantitation. To determine residual levels, the polymer was dissolved in dimethyl acetamide (DMAC)–water (99 + 1). On the average, >85% of the benzene was recovered. The quantitative determinative limit for the analysis was ca 200 ppb on a polymer basis. Migration tests simulating hot-filling or pasteurization above 150°F (66°C) were undertaken, using water as the food-simulating solvent. A lower limit of ca 0.35 ppb benzene could be quantitated. Several commercial products were examined, including samples of foam, impact, and crystal polystyrene. The levels of benzene found ranged from none to 3.47 ppm. The presence of benzene was confirmed by GC–mass spectrometry.
Comparison of Chemiluminescent and AOAC Methods for Determining Nitrite in Commercial Cured Meat Products
Authors: Fiddler Walter , Doerr Robert C , Gates Robert A , Fox Jay B
Published: February 2020

A chemiluminescent detector was used to measure nitrite in a variety of commercial cured meat products, using the AOAC sample preparation procedure, 24.041. A comparison of the NaNO2 values obtained by using sulfanilamide/N-(1-naphthyl)ethylenediamine (SAN/NED) reagent, sulfanilamide/1-naphthylamine reagent, and chemiluminescent detection (CLD) revealed no significant differences between the latter 2 detection methods. The AOAC SAN/NED reagent combination gave an average of 24.6% lower NaNO2 results than CLD. Examination of the sample preparation extraction and heating steps indicated that the procedure could not be made more rapid because of the need to destroy residual reductants and release “bound-complexed-reacted” nitrite from the meat samples.
Spectrophotometric Determination of Bromhexine Hydrochloride in Pharmaceutical Preparations
Authors: Santoro Maria Inês R M , Dos Santos Mirza M , Magalhães João F
Published: February 2020

The presence of an aromatic primary amino group in bromhexine HCI enables the use of diazotization-coupling, according to the classic Bratton-Marshall method, for its analysis in pharmaceutical preparations. Spectrophotometric parameters were established for standardization of the method, including statistical analysis of data. Substances such as potassium guaiacolsulfonate, ampicillin, cephalexin, oxytetracycline HCI, amoxycillin, and erythromycin ethylsuccinate do not interfere with the determination. The precision of the method is about 2.0%.
Verification of Authenticity of Orange Juice
Authors: Brause Allan R , Raterman Joseph M , Petrus Donald R , Doner Landis W
Published: February 2020

A series of instrumental analyses is used for verification of the authenticity of orange juice: liquid chromatography for sugars, UV-visible spectrophotometry for absorbance measurements, stable isotope ratio analysis of δ13C and δ18O values, and atomic absorption spectrophotometry for potassium and sodium analyses. All authentic orange juices possess positive δ18O values, while those of ground water and water in beet invert syrups are negative. Hence, addition of either to orange juices decreases δ18O values, and allows detection of nonauthentic products.
Gas Chromatographic Analysis of Coyote and Magpie Tissues for Residues of Compound 1080 (Sodium Fluoroacetate)
Authors: Okuno Iwao , Connolly Guy E , Savarie Peter J , Breidenstein Charles P
Published: February 2020

Tissues of coyotes and magpies administered known dosages of 1080 were analyzed for residues by an analytical method specifying gas chromatography and electron capture detection. The repeatability of the method was determined for the replicate analyses of coyote muscle tissue samples aged under different storage conditions. The average coefficient of variation (CV) was 6% for quadruplicate determinations of 1080 in fresh tissues, 12–14% for samples stored at – 10°C for 30–60 days, and 24 % for samples aged for 7 days at ambient temperatures. The larger CV value obtained for stored samples is attributed more to greater sample variability than to less precision of the analytical method. Residues of 1080 appear to be relatively stable in tissues; there was essentially no change in the concentration of 1080 in samples stored up to 28 days at ambient temperature. Residue levels in the muscle, heart, kidney, and intestine were comparable, slightly lower in the liver, and much higher in the stomach. The concentration of 1080 in the muscle tissue was related to the administered dosages. Correlation analyses of dosages and residue levels in coyote muscle tissue showed a correlation coefficient of 0.99 for 1080 administered by gavage, and 0.88 for 1080 administered by bait. A correlation coefficient of 0.99 was observed between dosages and mean residues in the breast muscle tissues of magpies. The average CV value was 3.5% for duplicate analyses of 1 g samples of magpie tissues.
Pad-Plate Diffusion Assay for Virginiamycin in Mash-Type Feeds
Authors: Katz Stanley E , Katz Jack M , Miller James A , Wang Richard , Shapiro Ralph
Published: February 2020

An assay procedure has been developed for virginiamycin in mash-type feeds which includes removing fat interferences from the feeds by a rapid petroleum ether wash, a citric acid extraction, an acetone extraction, and the use of the pad-plate diffusion system. The procedure eliminates the need for compensatory curves prepared from feeds of the same or similar composition. Recoveries from 10 laboratory-prepared feeds containing 11.0 μg virginiamycin/g averaged 89.3% with a coefficient of variation (CV) of 5.76%. Recoveries from a laboratory-prepared feed containing 13.2 μg virginiamycin/g averaged 89.9% (CV 9.92%). The procedure is simple, reasonably accurate, and precise.
Rapid Assay for Tetracycline in Premixes and Mixed Feeds
Authors: Katz Jack M , Katz Stanley E
Published: February 2020

A rapid assay for tetracyclines in premixes and mixed feeds is described, which uses the extraction and dilution systems of AOAC methods, and a strain of Bacillus stearothermophilus ATCC 12980 selected to grow at 40°C. The incubation period is 4.5 h. The rapid assay yields results similar to those obtained using the AOAC methods. For a 50 g chlortetracycline (CTC)/lb commercial premix, the rapid procedure averaged 109.2% of label vs 104.4% obtained using the AOAC method; for a 20 g CTC/lb premix, the rapid procedure averaged 89.2% vs 89.3% obtained with the AOAC method. In 2 commercial premixes containing 50 g oxytetracycline/lb, the rapid assay averaged 127.1 and 110.5% vs 134.7 and 113.5% obtained using the AOAC method. In feed extracts supplemented with CTC equivalent to 25–200 g/ton, rapid assay recoveries averaged 101.9%; recoveries using the AOAC method averaged 110.6%. For feed extracts supplemented with oxytetracycline at the same levels, recoveries by the rapid assay averaged 95.4%, and by the AOAC method, 106.0%.
Ion-Pair Extraction Cleanup for Liquid Chromatographic Determination of Bentazon in Crops and Soil
Authors: Åkerblom Malin , Alex Gunborg
Published: February 2020

Bentazon was selectively extracted as an ion pair with tetrabutylammonium ion into dichloromethane. This technique was used to clean up crop and soil samples before determination of bentazon by reverse phase liquid chromatography and UV detection. Recoveries from potatoes, cucumbers, wheat grain, and clay soil were 77–103%, with a detection limit of 0.02 mg/kg.
Rapid Differential Pulse Polarographic Determination of Tiaprofenic Acid
Authors: Mohamed Mohamed E , Wahbi Abdel-Aziz M , Gad-Kariem EL Rasheed A , Hassan Mahmoud M A
Published: February 2020

Tiaprofenic acid (Surgam®) has been determined directly by using differential pulse polarography (DPP) and pH 5.5 acetate buffer as a supporting electrolyte. The differential pulse polarogram was obtained under constant amplitude pulses of 50 mV superimposed on a linearly increasing dc ramp. Peak current was measured at the peak potential of — 0.990 V vs Ag/AgCl reference electrode. Under the experimental conditions used, a linear relationship between peak current and concentration was established over the range 0.5-5.0 ng/mL. Mean percentage recoveries for tiaprofenic acid in authentic and tablet forms were 100.27 ± 2.25 and 99.45 ± 1.44, respectively. The results obtained by the DPP method were compared with those of the spectrophotometric method used by the manufacturer for the analysis of tiaprofenic acid and its tablet form.
Nonaqueous Reverse Phase Liquid Chromatographic Analysis for Cholesterol in Milk Chocolate
Authors: Hurst W Jeffrey , Aleo Michael D , Martin Robert A
Published: February 2020

A method using liquid chromatography was developed for the analysis of cholesterol in milk chocolate products. The method involves saponification of the sample with methanolic KOH followed by extraction with ether. Potentially interfering components are eliminated through the use of a silica Sep-Pak cleanup step before injection. The nonaqueous reverse phase LC system consists of a C18 column and an isopropanol- hexane mobile phase with direct detection at 205 nm. Recoveries of 1, 3, and 5 mg cholesterol added to 1 g sample of milk chocolate were 88.6, 102.8, and 110.1%, respectively. Studies conducted with [4-14C]-cholesterol were undertaken to further document the accuracy of the method.
Evaluation of Electron Capture Gas Chromatographic Method for Determination of Methyl Mercury in Freezer-Case Seafoods
Authors: Alvarez George H , Hight George H , Capar Stephen G
Published: February 2020

A method was recently adopted by AOAC for determination of methylbound mercury in canned and fresh-frozen seafood by electron capture gas chromatography. That method was applied to the analysis of commercially prepared freezer-case seafoods. None of the commercially added ingredients produced electron capture responses that interfered in the analysis for methyl mercury. Recoveries of 95.7-114% were obtained in fortification studies of methyl mercury at 0.2 and 1.0 ppm levels. The applicability of aqueous methyl mercuric chloride solution for fortification studies was demonstrated.
SIMCA (Soft Independent Modeling of Class Analogy) Demonstrated with Characterization and Classification of Italian Olive Oil
Authors: Marie-Paule Derde , Danny Coomans , Désiré L Massart
Published: February 2020

The multivariate technique SIMCA (soft independent modeling of class analogy) has been applied to the classification of foodstuffs on the basis of gas chromatographic profiles of some of their constituents. The data set used in this investigation consists of the percentage distribution of 7 fatty acids (7 variables) in 100 samples of virgin olive oil from 2 different regions (2 classes) of Italy, East and West Liguria. The SIMCA method can be used to compute whether an olive oil sample from Liguria originated in the western or eastern part of this region, while 98.8% of samples that do not originate in Liguria are correctly classified as outliers. The developed classification rules are adequate for identifying oils according to their origin. Standard decision diagrams (SDD) are very attractive tools for classification of new samples; the similarity between a new sample and each of the classes is easily computed. Consequently, the SDD visualizes any similarity toward each of the classes, and enables a decision on whether the new sample originates in one of the regions under study.
Gas Chromatographic Determination of Deoxynivalenol in Wheat with Electron Capture Detection
Authors: Ware George M , Carman Allen , Francis Octave , Kuan Shia
Published: February 2020

A method is described for the determination of deoxynivalenol (DON) in wheat. The method involves sample extraction with chloroformethanol (8 + 2), column chromatographic cleanup on silica gel of small particle size, and derivatization with heptafluorobutyric acid anhydride using 4-dimethyIaminopyridine as a catalyst. The derivative DON trisheptafluorobutyrate is determined by gas chromatography using an electron capture detector. Recoveries of DON added to wheat at levels of 118—1184 ng/g averaged 88% with a coefficient of variation of 8.6%.
Identification of Aflatoxins by Quadrupole Mass Spectrometry/Mass Spectrometry
Authors: Plattner Ronald D , Bennett Glenn A , Stubblefield Robert D
Published: February 2020

MS/MS daughter experiments were recorded for aflatoxins B1, B2, G1, G2, M1, M2, and aflatoxicol, using 3 ionization modes. Daughters were recorded from the molecular ion (M+) using electron impact ionization (EI). Daughters from the protonated molecules (MH+) were recorded in the positive ion mode and the daughters from the molecular anion (M+) were recorded in the negative ion mode using chemical ionization (CI). These daughter spectra are all relatively simple. The EI daughters are quite similar to conventional EI spectra. The yield of (M-) is about 100 times greater than the yield of M+ in EI or MH+ in isobutane CI spectrum. Negative ion daughter spectra were used to demonstrate the feasibility of determining the presence of aflatoxin B1 in crude extracts of contaminated corn. Aflatoxin B1 could be detected at 10 ppb.