bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas Chromatography of Uracil Herbicides by On-Column Methylation with Trimethylanilinium Hydroxide
Authors: Ogierman Leonard
Published: February 2020

Substituted uracil herbicides injected into a gas chromatograph react with trimethylanilinium hydroxide to give iV-methyl derivatives with good gas chromatographic properties. Maximum methylation is obtained when the molar ratio of methylating reagent to herbicide is ca 4:1. This technique for preparing derivatives provides rapid qualitative and quantitative chromatography of the substances examined. Chromatographic response was linear with increased concentration for the synthetic standard and the on-column product of uracil herbicide. The proposed derivatization method was used to analyze herbicides in formulations. The methyl derivatives were identified spectroscopically
Current Trends in Levels of Volatile N-Nitrosamines in Fried Bacon and Fried-Out Bacon Fat
Authors: Canas Benjamin J , Havery Donald C , Joe Frank L , Fazio Thomas
Published: February 2020

Commercially processed bacon samples purchased from the Washington, DC, retail market have been periodically analyzed since 1971 for the presence of volatile A'-nitrosamines in the fried product. During that time, a downward trend in the concentration of N-nitrosopyrrolidine has been observed, and between 1978 and 1980 it plateaued at 4 - 30 ppb, with an average of 11 ppb. A recent survey, however, indicates a change in this downward trend, with A'-nitrosopyrrolidine found at levels ranging from 1 to 65 ppb, average 21 ppb. Volatile N-nitrosamines were found at levels up to 110 ppb in the fried product and up to 85 ppb in the fried-out bacon fat.
Surrogate-Assisted Determination of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin in Fish by Electron Capture Capillary Gas Chromatography
Authors: Niemann Richard A
Published: February 2020

Surrogate spiking the sample with 1000 parts per trillion (pptr) 1,3,7,8-tetrachlorodibenzo-p-dioxin (1378-TCDD) has doubled analytical throughput in determining toxic 2378-TCDD (analyte) at the low partper- trillion level in fish, using multicolumn high resolution liquid chromatographic cleanup before quantitation by capillary gas chromatography with electron capture detection. The 1378- and 2378-TCDD were recovered equally and were well separated by the capillary column so that the earlier-eluting surrogate did not interfere with the quantitation of levels of analyte many-fold lower. Matrix interference contributed <1 % bias in surrogate quantitation. Using surrogate recovery to correct for analyte losses during analysis, accuracy averaged (n = 7) 105% in determining 18 or 45 pptr 2378-TCDD added to fish without detectable bioincurred analyte. Analyses of selected fish with bioincurred 2378-TCDD gave results comparable to earlier work where recovery correction required a second analysis of sample fortified with analyte. With surrogate fortification, repeatability of determination (n = 3 or 4) improved markedly to <5% relative standard deviation at 37-46 pptr.
On-Line Trace Enrichment for Determination of Aldicarb Species in Water, Using Liquid Chromatography with Post-Column Derivatization
Authors: Chaput Daniel
Published: February 2020

Liquid chromatography combining on-line trace enrichment together with a very selective detection technique is used for the determination of aldicarb, aldicarb sulfoxide, and aldicarb sulfone. Sensitivity is increased by loading a 10 mL volume of ground water on a concentrator column installed in the loop position of a 6-port injection valve. Switching the valves allows the concentrated material to be backflushed onto the analytical column by a methanol-water gradient mobile phase. Separation is followed by post-column hydrolysis to yield methylamine, and formation of a fluorophore with o-phthalaldehyde and 2-mercaptoethanol prior to fluorescence detection. The process requires virtually no sample cleanup and provides good precision on recoveries from different matrixes. Minimum detection limit, defined as 5 times baseline noise, is less than 70 ng/L for the 3 compounds.
Detection of Pork and Lard as Adulterants in Beef and Mutton Mixtures
Authors: Saeed Talat , Abu-Dagga Faisal , Rahman Hani Abdul
Published: February 2020

Detection of pork and lard in different beef and mutton mixtures was investigated. The extracted fat was hydrolyzed and esterified to methyl esters of fatty acids, which were then analyzed on a fused silica capillary ' column coated with FFAP. Gas chromatographic analysis showed that 11,14-eicosadienoic acid (C20.2) can be used as an indicator for the presence of pork or lard in beef and mutton mixture. C20:2 is not detected in beef or mutton and is present in pork and lard. Overall composition of the fatty acids can be used for rough estimation of sample composition. Using this method, a detection limit of 1% pork in beef and mutton was reached.
On-Column Partition Cleanup of Fatty Extracts for Organophosphate Pesticide Residue Determination
Authors: Di Muccio Alfonso , Cicero Anna Maria , Camoni Ivano , Pontecorvo Damiano , Dommarco Roberto
Published: February 2020

A fast, single-step, and efficient partition between n-hexane and acetonitrile on ready-to-use, disposable mini-columns of Kieselghur-type material has been developed for the cleanup of fatty extracts for organophosphate (OP) pesticide residue determination by gas chromatography with flame photometric detection. Nine OP pesticides (diazinon, etrimfos, chlorpyrifos-methyl, pyrimiphos-methyl, chlorpyrifos, bromophos, bromophos-ethyl, malathion, fenitrothion) most commonly used for protection of stored cereals, oil seeds, and legumes were separated from up to 2.0 g lipidic material with recoveries between 80 and 107% at spiking levels ranging for the different compounds from 0.1 to 5.0 ppm.
Automated Sample Cleanup for Pesticide Multiresidue Analysis. III. Evaluation of Complete System for Screening Subtolerance Residues in Vegetables
Authors: Gretch Fred M , Rosen Joseph D
Published: February 2020

An automated continuous flow sample cleanup system intended for rapid screening of foods for pesticide residues in fresh and processed vegetables has been developed. Recovery and precision data for 8 pesticides in each of 3 crops are compared for the automated and manual procedures. Average recovery for samples fortified with pesticides between 0.026 and 0.277 ppm was 98% for the automated system and 92% for the manual procedure. Average coefficient of variation was 6.6% for the automated system and 4.2% for the manual procedure. In another evaluation, the automated system gave an average recovery of 95% for 12 pesticides commonly found in imported foods; the manual procedure gave an average recovery of 91%. Thus, the results obtained so far indicate that the automated system for sample cleanup gives results comparable to those obtained by manual procedures.
Cyclopiazonic Acid Production by Cultures of Aspergillus and Penicillium Species Isolated from Dried Beans, Corn Meal, Macaroni, and Pecans
Authors: Trucksess Mary W , Mislivec Philip B , Young Kathryn , Bruce Verneal R , Page Samuel W
Published: February 2020

Ninety-five isolates of Aspergillus and Penicillium species from selected dried foods were examined for their ability to produce cyclopiazonic acid (CPA). The isolates were grown in sterile synthetic liquid medium at 28°C for 8 days in the dark. The medium and mold mycelia were then extracted with chloroform. CPA was semiquantitative^ determined by thin layer chromatography through visual comparison with standards. The cultures of A. flavus were also examined for their ability to produce aflatoxin. One A. tamarii and all 13 P. urticae isolates produced CPA, whereas only 19 of the 31 (61%) A. flavus isolates produced CPA, and 6 (19%) A. flavus produced aflatoxin. All 13 P. urticae isolates also produced patulin and griseofulvin. CPA-producing A. flavus was found in all food types but not in all samples. CPA-producing P. urticae was found only in dried beans and macaroni.
Quantitative Analysis of Cystine, Methionine, Lysine, and Nine Other Amino Acids by a Single Oxidation-4 Hour Hydrolysis Method
Authors: Gehrke Charles W , Rexroad Paul R , Schisla Robert M , Absheer Joseph S , Zumwalt Robert W
Published: February 2020

The sulfur-containing amino acids cystine and methionine play important roles in animal, especially avian, nutrition. Because these ndror-containing amino acids are destroyed to varying extents by 6N HC1 hydrolysis, oxidation and hydrolysis of cystine to cysteic add and methionine to methionine sulfone have been widely used for determination of cystine and methionine. Lysine is considered the next limiting amino acid after the sulfur amino acids in poultry •ntrition; therefore, determination of the amino acid content of rations focuses first on these 3 amino acids. The objective of this investigation was to establish whether lysine and other amino acids could be accurately determined in proteinaceous materials which had mdergone performic acid oxidation. To perform this evaluation, lysine was determined in a variety of protein-containing materials both with and without performic acid oxidation. Performic acid oxidation followed by 6N HC1 hydrolysis at 145°C for 4 h allows accurate measurement of 3 amino acids especially important to poultry nutrition, cystine, methionine, and lysine, in a single preoxidized hydralysate; this method can be extended to another 9 protein amino adds.
Mass Spectrometric Evidence for Demethylated Homologs Occurring at Trace Levels in Trichothecene Standards
Authors: Visconti Angelo , Mirocha Chester J , Pawlosky Robert J
Published: February 2020

Compounds with molecular weights 14 a.m.u. lower than their corresponding parent compounds have been detected in trichothecene standards during gas chromatography-mass spectrometry analysis. The positive ion chemical ionization mass spectra indicated that these compounds were trichothecene homologs lacking a methyl group on the isovaleroxy substituent at the C-8 position. Demethylated derivatives have been found in the standards of T-2, HT-2, and T-2 triol prepared in our laboratory and those obtained from a commercial source.
Simplified Method for Determining Polychlorinated Biphenyls, Phthalates,and Hexachlorocyclohexanes in Air
Authors: Stein Vincent B , Amin Thakor A. , Narang Rajinder Singh
Published: February 2020

A simplified method for determining polychlorinated biphenyls (PCBs), phthalates, and benzene hexachlorides (BHCs) in air has been developed. Florisil is used as the adsorbent, and compounds are elated by liquid chromatography with 10% 2-propanol in hexane. PCBs are separated from phthalates plus BHCs on a cyanopropyl column with a gradient containing 10% 2-propanol in hexane and 100% hexane as the mobile phase. Two fractions are collected: one contains PCBs and the other contains phthalates plus BHCs, which ve then determined by gas chromatography using a 63Ni electroncapture detector and a DB-5-bonded, fused-silica capillary column.
Capillary Column Gas Chromatographic Determination of Ethyl Carbamate in Alcoholic Beverages with Confirmation by Gas Chromatography/Mass Spectrometry
Authors: Conacher Henry B.S. , Page B.Denis , Lau Benjamin P.Y. , Lawrence James F. , Bailey Ruth , Calway Patrick , Hanchay Jean-Pierre , Mori Brian
Published: February 2020

A method is described for determining ethyl carbamate at low \i%l kg levels in several types of alcoholic beverages by capillary column gas chromatography with Hall electrolytic conductivity detection and confirmation by mass spectrometry. Samples are diluted to obtain a uniform concentration of ethanol (ca 10%) then saturated with NaCl and extracted with methylene chloride. Extracts are evaporated to a small volume and injected in ethyl acetate solution for chromatographic analysis. The method was evaluated by 5 laboratories, 4 employing the Hall detector and one using mass spectrometric detection. Overall between-laboratory mean percent recoveries were: wine, 85.3 ± 21.0% coefficient of variation (CV) (spiking level 20- 45 μg/kg); sherry, 83.8 ± 16.1% CV (spiking level, 81-142 μg/kg);whiskey, 79.5 ± 13.9% CV (spiking level 127-190 Mg/kg); and brandy, 85.0 ± 12.5% CV (spiking level 297-446 μg/kg). Mass spectrometric results agreed well with the Hall results for all commodities. Detection limits were about 5 μg/kg for the Hall detector and about 0.5 μg/kg for mass spectrometric detection.
Lead, Cadmium, and Fluoride Levels in Market Milk and Infant Formulas in Canada
Authors: Dabeka Robert W. , Mckenzie Arthur D.
Published: February 2020

Lead, cadmium, and fluoride were determined in 68 samples of market milk and about 115 infant formulas. Mean and median levels (ranges) in ng/g found for cow milk were as follows: lead, 1.12, 1.19 (0.01-2.48); cadmium, 0.10, 0.039 (0.005-0.74); and fluoride, 41, 40 (7-86). In canned, ready-to-use formulas, lead, cadmium, and fluoride levels averaged 37.3,1.50, and 840 ng/g, respectively. In concentrated liquid formulas, the respective levels were 21, 3.54, and 600 ng/g. In powder formula concentrates, respective levels were 73.7, 6.78, and 1130 ng/g. On the basis of this study and literature data, lead levels in market milk exceeding 5 ng/g appeared to signify contamination of the milk either directly or via the cow. For formulas considered on an as-consumed basis, lead levels exceeding about 10-15 ng/g were attributed to contamination from either the can used to store the formula or the formula ingredients. Infant formulas in lead-free cans contained about 1.7 ng/g of lead on a ready-to-use basis. Milkbased formulas contained about 0.26 ng/g of cadmium on a readyto- use basis. Soy-based or milk-free formulas contained about 8-15 times more cadmium than did milk-based formulas. Canadian and U.S. ready-to-use formulas contained 900 and 230 ng/g fluoride, respectively, and this difference was attributed to the level of fluoride in the processing water used by the manufacturers.
Simple Liquid Chromatographic Method for Determination of Carotenoids in Alfalfa Products
Authors: Lauren Denis R , McNaughton Donald E , Agnew Michael P
Published: February 2020

A dichloromethane extraction system has been developed which is suitable for alfalfa carotenoids and is compatible with nonaqueous reverse phase liquid chromatographic (LC) analysis. Ground samples are extracted in the presence of antioxidant with dichloromethaneacetone (2 + 1). After an overnight soak, the mixture is saponified with 40% w/v potassium hydroxide in methanol and then is partitioned with 10% w/v aqueous sodium sulfate. An aliquot of the lower yellow organic phase is used for LC analysis after dilution (1 + 1) with acetonitrile. An isocratic 2 solvent system of ethyl acetateacetonitrile containing 0.1% n-decanol as mobile phase modifier is used for liquid chromatography with a high carbon loading non-endcapped ODS packing material. In comparisons with the existing AOAC method for carotenes and xanthophylls in dried plant materials and mixed feeds, the proposed method gave consistently higher results in a range of 7-28%, depending on the substrate. Possible causes for the differences were examined and include losses during partition and column chromatography with the AOAC method. Calculation methods and the choice of standard materials may also contribute to the difference in results.
CoUisionally Activated Decomposition Mass Spectrometry/Mass Spectrometry Determination of Organophosphorus Pesticide Residues in Foods
Authors: Roach John A G , Carson Louis J
Published: February 2020

Btpresentative collisionally activated decomposition mass spectrometry/ mass spectrometry spectra of omethoate, parathion, and azinffeas- methyl pesticides are described. Crude and cleaned up extracts af strawberries or lettuce fortified at the 0.2 ppm level with omethoate, parathion, and azinphos-methyl were examined using the direct exposure probe. Cleaned up extracts produced better data because the large overburden of interfering coextractives was removed
Classification of Octadecyl-Bonded Liquid Chromatography Columns
Authors: Walters Milda J
Published: February 2020

The differences in performance characteristics exhibited by columns available under the same octadecyl (C-18) label cause difficulties for the authors and users of official methods. This paper presents a simple scheme for classifying C-18 columns on the basis of the 2 predominant reverse phase retention mechanisms—hydrophobic and silanophilic interactions, which are dependent on the hydrocarbon coverage and the unreacted silanol sites, respectively. Hydrophobic interactions are represented by the ratio of anthracene k : benzene k in an acetonitrile-water (65 + 35) mobile phase. The unreacted silanols are represented by the /V,/V-diethyltoluamide k : anthracene k ratio with acetonitrile as the mobile phase. Column efficiency, which is largely dependent on particle size and packing technique, is included as a third classification criterion. Twelve brands of C-18 packings were subjected to this test scheme and qualitatively classified into 3 major groups on the basis of 3 criteria: hydrophobicity index, free silanol index, and efficiency. This scheme is intended as an aid in the selection of similar or equivalent columns and in defining the type of column suitable for an analytical method.
Determination of Anatoxin M, in Milk and Milk Products Contaminated at Low Levels
Authors: Dominguez Lucas , Blanco Jose L , Gomez-Lucia Esperanza , Rodriguez Elias F , Suarez Guillermo
Published: February 2020

A new method is described for the determination of aflatoxin M, in milk and dairy products by thin layer chromatography. The main characteristic is the extraction system using an alkaline solution. Lipids are removed by centrifuging at low temperatures, and the aflatoxins are then extracted with CHC13. The method has 2 options: Technique II (detection limit 0.02 ppb) requires cleanup on a chromatographic column; this is not necessary in Technique I (detection limit 0.1 ppb). The recovery rate in both techniques is over 92.8% in milk and yoghurt. This method may also be used for other aflatoxins. Because of the advantages of the method, Technique II is recommended for aflatoxin M1, control in milk, where a low detection limit is necessary. Technique I is proposed for experimental aflatoxin production studies in dairy products, which require analysis of a large number of samples but which do not require a very low detection limit.
Liquid Chromatographic Determination of Aflatoxicol in Porcine Liver
Authors: Tyczkowska Krystyna , Hutchins James E , Hagler Winston M
Published: February 2020

A liquid chromatographic (LC) method for determination of aflatoxicol in porcine liver was developed. Liver sample is homogenized with water, diluted with saturated Na2S04 solution, and extracted with acetone. After filtration, less polar interferences are removed by partition with isooctane. Aflatoxicol in the aqueous fraction is partitioned into CHC13. The extract is dried over anhydrous Na2S04 and evaporated nearly to dryness at 35°C under a gentle flow of dry filtered air or nitrogen. Residue is dissolved in CHCl3-hexane and applied to a hexane-activated silica cartridge. The cartridge is washed with hexane-CHClj, then aflatoxicol is eluted with CHCl3-acetone. Purified extract is evaporated to dryness, dissolved in methanol, and analyzed by C18 reverse phase liquid chromatography using a water- CHjCN-acetic acid mobile phase and fluorescence detection. Recovery of aflatoxicol from spiked liver samples at levels ranging from 0.25 to 4.0 ng aflatoxicol/g wet tissue averaged 92% with a limit of detection of about 0.1 ng aflatoxicol/g liver.
Determination of Reserpine and Rescinnamine in Rauwolfia serpentina Preparations by Liquid Chromatography with Fluorescence Detection
Authors: Cieri Ugo R
Published: February 2020

A method is presented for the determination of reserpine and rescinnamine in Rauwolfia serpentina powder or tablets by liquid chromatography (LC) with fluorescence detection. The sample is dispersed in CH3OH, 0.5N H2S04 is added, and the mixture is extracted with five 30 mL portions of CHC13. The extracts are separated from interfering materials on a Celite-O.IN NaOH column, and the eluates are collected in 50 mL CH3OH. After complete removal of the CHC13, reserpine and rescinnamine are determined by liquid chromatography on a normal phase column with CH3OH as the mobile phase. Because reserpine and rescinnamine produce a single peak, chromatograms are obtained at different wavelengths. Reserpine is determined at an excitation wavelength of 280 nm and an emission wavelength of 360 nm. Rescinnamine is determined at an excitation wavelength of 330 nm and an emission wavelength of 435 nm. Recovery studies were conducted at 2 different levels to simulate 100 and 50 mg Rauwolfia serpentina tablets. Samples of Rauwolfia serpentina powders and tablets were also examined, and the results were compared with those obtained by the current AOAC official method. The proposed method is applicable to the analysis of ground composites and individual tablets.
Analysis of Selected Drug Formulations for Volatile Nitrosamines
Authors: Dawson Brian A , Lawrence Robert C
Published: February 2020

A number of selected drug formulations on the Canadian market were analyzed for A'-nitrosodimethylamine (NDMA) and /Y-nitrosodiethylamine (NDEA) content by using a gas chromatograph interfaced to a thermal energy analyzer (GC/TEA). Of the 34 formulations analyzed, NDMA was found in 21 at levels up to 12 ppb and NDEA was found in 11 at levels up to 0.6 ppb. In many cases, the drug entity in the formulation did not contain the precursors for the observed nitrosamines.
Differential Pulse Polarographic Determination of Sulfites in Foods: Collaborative Study
Authors: Holak Walter , Patel Bhailal
Published: February 2020

A differential pulse polarographic (DPP) method for the determination of "free" and "total" sulfite in foods was collaboratively studied by 8 laboratories. The collaborators analyzed blind duplicate samples of shrimp, orange juice, peas, dried apricots, and dehydrated potatoes. Collaborators also analyzed the same samples spiked with sulfites at 2 levels, which ranged from 10 to 1100 ng added S02/g. The variability of free S02 results was excessive for quantitative analysis, but the method can be used for qualitative detection of free S02. The method for total S02 determination was suitable for as low as approximately 10 μg/g. Recoveries are comparable to those for the official Monier-Williams method at high levels and are superior at low levels. The method has been adopted official first action for determination of total S02 in the foods studied.
Monitoring Residues of Carbendazim (Applied as Benomyl) and Thiabendazole in Wellspur Apples
Authors: Monico-Pifarre Amalia , Xirau-Vayreda Maria
Published: February 2020

Residues of benomyl (determined as carbendazim, widely accepted as MBC) and of thiabendazole in Wellspur apples were monitored after the apples were treated postharvest by immersion in a bath with each of the fungicides separately and stored under refrigeration. Whole fruit and pulp analyses were conducted over the period beginning 1 day after treatment and lasting up to 200 days afterwards. Under the conditions described, both benomyl (expressed as parts per million of carbendazim) and thiabendazole were found in the fruits in the following average amounts: 0.44 ± 0.03 and 0.11 ± 0.03 ppm benomyl (as carbendazim) in whole fruit and in pulp, respectively; 0.98 ± 0.10 and 0.39 ± 0.10 ppm thiabendazole in whole fruit and in pulp, respectively.
Determination of Vitamin D3 in Liquid Multivitamin Preparation, Using Reverse Phase, Solid Phase Extraction Liquid Chromatography
Authors: Pluscec Josip , Owies Said
Published: February 2020

A method is described for the determination of vitamin D,in a liquid multivitamin preparation by liquid chromatography. Samples are purified on a disposable reverse phase extraction (SPE) column with a mobile phase of methanol-2-propanol (97 + 3) and are analyzed on a Zorbax ODS (5 μm) column with an acetonitrile-2-propanolwater( 90 + 8 + 2) solvent system. Vitamin D3is completely resolved from other interfering compounds within approximately 21 min and is detected with a UV detector at 254 nm. A mean of 98.5% of theory with a coefficient of variation of 3.8% was found for determination of vitamin D, in a commercial preparation.
Quantitative Connrmation of Dimetridazole and Ipronidazole in Swine Feed by Capillary Gas Chromatography/Mass Spectrometry with Multiple Ion Detection
Authors: Morris William J , Nandrea Gene J , Roybal Jose E , Munns Robert K , Shimoda Wilbert , Skinner Henry R
Published: February 2020

Extracts from 4 types of swine feed containing 0.11 ppm each of dimetridazole (DMZ) and ipronidazole (IPR) were analyzed by capillary gas chromatography/mass spectrometry (GC/MS) using multiple ion detection (MID) techniques. We demonstrate in this paper that the quantitative results obtained by capillary GC/MS with MID are comparable for both compounds to results obtained by liquid chromatography and have a lower coefficient of variation for DMZ. Moreover, consistency in the ion ratios (5 ions in DMZ and 6 ions in IPR) permits identification of these compounds by electron ionization MS.
Simplified Plate Diffusion System for Microbial Assays of Antibiotics
Authors: Brady Marietta Sue , Katz Stanley E
Published: February 2020

A protocol for microbial assays of antibiotics, using the plate diffusion system, is presented. The system is based on the concept that a complete standard curve and assay unknowns can be placed on an issay plate and that 2 plates can be a complete assay with an accuracy and precision essentially equivalent to the official AOAC diffusion procedure. Four antibiotics, bacitracin, chlortetracycline, oxytetracycline, and streptomycin, were used in the design and comparison studies with the AOAC protocol. The coefficients of variation (CVs) for the AOAC design, using 10 replicates, ranged from 1.4 to 10.3% with a mean of 4.5%. The CVs for the single-plate option of the simplified design ranged from 4.3 to 9.6% with a mean of 6.6%; the CVs for the 2-plate option ranged from 2.5 to 6.8% with a mean of 43%; the CVs for the 3-plate option ranged from 1.2 to 5.0% with a mean of 3.0%.
Simultaneous Analysis of T-2 Toxin and HT-2 Toxin by an Indirect Enzyme-Linked Immunosorbent Assay
Authors: Fan Titan S L , Xu Yi-Chun , Chu Fun Sun
Published: February 2020

An indirect enzyme-linked immunosorbent assay (ELISA) for the detection of HT-2 toxin in the presence or absence of T-2 toxin is described. In the indirect ELISA, the relative cross-reactivities of antibodies against T-2 toxin (anti-T-2) with T-2 toxin and HT-2 toxin were 1 and 0.1, whereas anti-HT-2 cross-reactivities with T-2 toxin and HT-2 toxin were 0.33 and 1, respectively. Using such relationships, a formula was established that could be used to calculate the individual toxin concentration in a mixed sample after experimentally analyzing for T-2 and HT-2 toxins in the 2 indirect ELISAs. This method was tested by analyzing urine samples spiked with HT-2 toxin alone and samples spiked with both T-2 toxin and HT-2 toxin. A cleanup protocol for treatment of urine samples before ELISA was also established. The overall analytical recovery of HT-2 toxin when it was added at concentrations of 0.1-10 parts per billion (ppb) to the urine samples was ca 89%. When both T-2 and HT-2 toxins were added to the urine samples at equal concentrations of 0.5 to 5.0 ppb, their recoveries were 112 and 109%, respectively.
Liquid Chromatographic Determination of Cinnamic and Benzoic Acids in Benzoin Preparations
Authors: Wahbi Abdel-Aziz M , Abounassif Mohammad A , Gad-Kariem El-Rasheed A , Ibrahim Mahmoud W
Published: February 2020

A liquid chromatographic method for the individual determination of benzoic and cinnamic acids in 2 benzoin preparations is presented. The method specifies a reverse phase column and 0.01M KH2P04- methanol (85 + 15) as mobile phase at a flow rate of 1.8 mL/min, with detection at 254 nm. The method has been applied to 2 benzoin preparations and the results were compared with those from the British Pharmacopoeia method.
Liquid Chromatographic Determination of Free and Added Niacin and Niacinamide in Beef and Pork
Authors: Takatsuki Keigo , Suzuki Shigeru , Sato Makiko , Sakai Keiich , Ushizawa Isamu
Published: February 2020

A simple liquid chromatographic (LC) method is described for the determination of free and added niacin and niacinamide in meats. A sample is homogenized and extracted with water, and the water extract is centrifuged, deproteinized with zinc hydroxide, and filtered first through a fluted paper and then through a microporous filter. The filtrate is subjected to liquid chromatography with UV detection at 263 nm. Different ion-pair systems are needed for the measurement of niacin and niacinamide on a reverse phase column. Methanolwater (1 + 9) containing 5mM tetrabutyl ammonium ion is used to separate niacin. Water containing lOmM heptane sulfonic acid is recommended for niacinamide. Recoveries (CV,%) are 104.8% (2.9%) for niacin and 96.3% (2.7%) for niacinamide at a 10 mg/100 g fortification level. Detection limit is 1 mg/100 g sample for niacin and niacinamide.
Simultaneous Liquid Chromatographic Determination of Residual Synthetic Antibacterials in Cultured Fish
Authors: Nose Norihide , Hoshino Youji , Kikuchi Yoshinori , Horie Masakazu , Saitoh Kouichi , Kawachi Takashi , Nakazawa Hiroyuki
Published: February 2020

A liquid chromatographic method is described to determine simultaneously the following 11 synthetic antibacterial agents used in a fishery: nitrofuran derivatives furazolidone, nifurpirinol, difurazone, and furamizole; sulfa drugs sulfamerazine, sulfisozole, sulfamonomethoxine, and sulfadimethoxine; and, oxolinic, nalidixic, and piromidic acids. A Nucleosil C18 column was used with tetrahydrofuran- acetonitrile-phosphoric acid-water (29 + 1 + 0.06 + 69.94) as the mobile phase. Pretreatment of the fish meat sample with acetone extraction and alumina column cleanup gave good separation of the LC peaks without interference from any other components. Recovery of the antibacterial agents was ca 80%. The lower limit of detection of the drugs was 1-2 ng for 10 μL injection.
Capillary Column Gas Chromatographic Determination of Ethyl Carbamate in Alcoholic Beverages with Confirmation by Gas Chromatography/Mass Spectrometry
Authors: Conacher Henry B S , Page Denis B , Lau Benjamin P Y , Lawrence James F , Bailey Ruth , Calway Patrick , Hanchay Jean-Pierre , Mori Brian
Published: February 2020

A method is described for determining ethyl carbamate at low \i%l kg levels in several types of alcoholic beverages by capillary column gas chromatography with Hall electrolytic conductivity detection and confirmation by mass spectrometry. Samples are diluted to obtain a uniform concentration of ethanol (ca 10%) then saturated with NaCl and extracted with methylene chloride. Extracts are evaporated to a small volume and injected in ethyl acetate solution for chromatographic analysis. The method was evaluated by 5 laboratories, 4 employing the Hall detector and one using mass spectrometric detection. Overall between-laboratory mean percent recoveries were: wine, 85.3 ± 21.0% coefficient of variation (CV) (spiking level 20- 45 μg/kg); sherry, 83.8 ± 16.1% CV (spiking level, 81-142 μg/kg);whiskey, 79.5 ± 13.9% CV (spiking level 127-190 Mg/kg); and brandy, 85.0 ± 12.5% CV (spiking level 297-446 μg/kg). Mass spectrometric results agreed well with the Hall results for all commodities. Detection limits were about 5 μg/kg for the Hall detector and about 0.5 μg/kg for mass spectrometric detection.
Lead, Cadmium, and Fluoride Levels in Market Milk and Infant Formulas in Canada
Authors: Dabeka Robert W , Mckenzie Arthur D
Published: February 2020

Lead, cadmium, and fluoride were determined in 68 samples of market milk and about 115 infant formulas. Mean and median levels (ranges) in ng/g found for cow milk were as follows: lead, 1.12, 1.19 (0.01-2.48); cadmium, 0.10, 0.039 (0.005-0.74); and fluoride, 41, 40 (7-86). In canned, ready-to-use formulas, lead, cadmium, and fluoride levels averaged 37.3,1.50, and 840 ng/g, respectively. In concentrated liquid formulas, the respective levels were 21, 3.54, and 600 ng/g. In powder formula concentrates, respective levels were 73.7, 6.78, and 1130 ng/g. On the basis of this study and literature data, lead levels in market milk exceeding 5 ng/g appeared to signify contamination of the milk either directly or via the cow. For formulas considered on an as-consumed basis, lead levels exceeding about 10-15 ng/g were attributed to contamination from either the can used to store the formula or the formula ingredients. Infant formulas in lead-free cans contained about 1.7 ng/g of lead on a ready-to-use basis. Milkbased formulas contained about 0.26 ng/g of cadmium on a readyto- use basis. Soy-based or milk-free formulas contained about 8-15 times more cadmium than did milk-based formulas. Canadian and U.S. ready-to-use formulas contained 900 and 230 ng/g fluoride, respectively, and this difference was attributed to the level of fluoride in the processing water used by the manufacturers.
Evaluation of AOAC Microbial Diffusion Procedure for Analysis of Chlortetracycline in High
Mineral Feeds
Authors: Katz Stanley E , Ragheb Hussein S , Black Lisa B
Published: February 2020

The performance of the AOAC microbial diffusion assay procedure for the analysis of chlortetracycline was evaluated in mixed feeds and premixes as well as laboratory-prepared feeds, all with various mineral contents. In 100 mixed feeds with a calcium content ranging from < 1 to > 22%, no relationship was shown between calcium content and incidence of chlortetracycline deficiency. In 106 premixes, a relationship was shown between chlortetracycline content and adherence to guarantee: below 10 g/lb, the incidence of deficiency was high; in premixes containing 20 g chlortetracycline and above, the incidences of deficiency were less than 5%. In laboratory-prepared feeds containing 12-15% calcium, grinding and storage at both 4°C and at room temperature (20°C) caused no decrease in the chlortetracycline concentration. Only storage of the ground feed at 37°C caused a distinct loss of activity. The temperature-related loss was attributed to the epimerization of chlortetracycline.
Determination of /V-Nitrosodiethanolamine in Dinoseb Formulations by Mass Spectrometry
and Thermal Energy Analyzer Detection
Authors: Wigfield Yuk Y , Gurprasad Narine P , Lanouette Monique , Ripley Sharon
Published: February 2020

A new method is described to determine trace quantities of A'-nitrosodiethanolamine (NDE1A) in aqueous diethanolamine (DE1A) formulations and in oil solutions of dinoseb. A formate anion-exchange column is used in series with a cation-exchange column if there is DE1A in the formulation. The eluate is then passed through a Clin Elur8 column. Depending on the concentration of NDE1A in the sample, a packed silica-gel column is used to purify the extract further. This extract is analyzed on a liquid chromatograph coupled with a thermal energy analyzer (LC/TEA), using a mixture of methanol- hexane-methylene chloride containing 0.1% acetic acid (8 + 56 + 35) as the mobile phase. This solvent system gives good separation of NDE1A from trace quantities of dinoseb remaining in the extract. The NDE1A is also converted to the trimethylsilyl derivative and analyzed by gas chromatograph coupled with a mass spectrometer (GC/MS). Analyses of 11 commercial samples of dinoseb diethanolamine salt showed NDE1A levels of 116-2409 ppm expressed relative to the weight of dinoseb. In contrast, analyses of 2 samples of organic solutions of technical dinoseb showed NDE1A levels to be nondetectable and 0.3 ppm, respectively. Limit of detection by LC/ TEA is 6.5 ng (0.5 ppm), and by GC/MS it is 0.02 ng (0.15 ppm). Recoveries from samples spiked at 0.514-1664 ppm range from 92.2 to 105.2%
Determination of Ethylene Oxide in Ethoxylated Surfactants and Demulsifiers by Headspace
Gas Chromatography
Authors: Dahlgran James R , Shingleton Carroll R
Published: February 2020

A headspace gas chromatographic method for the determination of traces of ethylene oxide in ethoxylated surfactants and demulsifiers was developed. Samples are analyzed directly by the technique to a 1.0 ppm (w/w) quantitation limit. The procedure also performs well for propylene oxide, acetaldehyde, and 1,4-dioxane. It is simple, sensitive, and linear. The percent relative standard deviations for 0.5 and 30 ppm ethylene oxide in the surfactant were 2.8 and 8.3%, respectively.
Liquid Chromatographic Determination of Depletion of Bithionol Sulfoxide and Its Two
Major Metabolites in Bovine Milk
Authors: Mourot Dominique , Dagorn MichÈle , Delepine Bernard
Published: February 2020

A liquid chromatographic method is described for determining bithionol sulfoxide and its metabolites, bithionol and bithionol sulfone, in milk. Samples are treated with HC1 to precipitate proteins and to permit extraction of bithionol sulfoxide in nonionized form. Tetrahydrofuran is added to the organic phase to facilitate extraction in diethyl ether; the dried residue is dissolved in chloroform, hexane, and sodium hydroxide and subjected to LC analysis. Residues of bithionol sulfoxide and its 2 metabolites were determined in milk of lactating cows. Holstein-Friesian dairy cows were administered a single oral dose of bithionol sulfoxide (50 mg/kg). Milk samples were analyzed with a reliable detection level of 0.025 pg/mL for each compound. Residues of bithionol sulfoxide and bithionol were detected during 30 and 16 milkings, respectively; bithionol sulfone was never present at detectable levels
Analysis of Piperazine Drug Formulations for /V-Nitrosamines
Authors: Dawson Brian A , Lawrence Robert C
Published: February 2020

A quantitative method is described for the measurement of /V-mononitrosopiperazine (NPIP) and TV.A^-dinitrosopiperazine (DNPIP) in drug formulations containing piperazine, using a gas chromatograph interfaced to a thermal energy analyzer (GC/TEA). The method has detection limits of 20 ppb for NPIP and 12 ppb for DNPIP. In a survey of 6 products available on the Canadian market, all contained NPIP at levels of 0.38-15.3 µg NPIP/g piperazine and none contained any detectable amount of DNPIP
Gas Chromatographic Relative Retention Data for Pesticides on Nine Packed Columns: II.
Organophosphorus and Organochlorine Pesticides, Using Electron-Capture Detection
Authors: Prinsloo Susan M , De Beer Pieter R
Published: February 2020

The retention time relative to parathion, absolute retention time, concentration range, peak asymmetry factor, and peak shape class are given for each of 42 organophosphorus pesticides and 28 organochlorine pesticides analyzed by gas chromatography (GC) on 9 different packed columns. The packing materials used were 3% SP- 2100, 1% Dexsil-300, 3% OV-17, 1.5% OV-17 + 1.95% QF-1, 4% SE-30 + 6% QF-1, 3% OV-17 + 3% OV-210, 5% DC-200 + 7.5% QF-1,3% Carbowax-20M, and 4% Reoplex-400. Retention data were determined at 200°C with a carrier gas flow at ūopt using a 63Ni electron-capture detector. Results should be useful for preliminary identification of environmental samples and also for single or multiple pesticide residue analysis
Correlations between Selected Trace Elements and Organic Matter and Texture in Sediments
of Northern Prairie Wetlands
Authors: Martin Dan B , Hartman William A
Published: February 2020

Total concentrations of arsenic, cadmium, lead, mercury, and selenium previously determined in wetland sediments were grouped according to habitat type and geologic location and related to sediment organic matter and particle size by stepwise multiple regression analysis. Cadmium and Se were significantly correlated with the measured sediment properties in every geologic and hydrologic category. Arsenic and Pb were consistently correlated with sediment properties in riverine habitats but not in potholes. In contrast, good correlations were found with Hg in potholes but not riverine wetlands. Organic matter concentration was the most consistent overall predictor of trace element concentrations, but texture was also a good indicator in some instances. The lack of correlation observed for some of the elements within given geologic categories suggests that other factors, such as external loading or deposition rates, were responsible for the observed variation
Gas Chromatographic Determination of Capsaicinoids in Green Capsicum Fruits
Authors: Krajewska Anna M , Powers John J
Published: February 2020

A new gas chromatographic (GC) method is described that uses a simple on-column methylation for the quantitative determination of the major naturally occurring capsaicinoids. Capsaicinoids are extracted from the dry sample with acetone in a Soxhlet apparatus, purified by extraction with petroleum ether and water, mixed in a microsyringe with trimethylanilinium hydroxide solution, and injected onto the GC column. The methylated capsaicinoids thus formed require 16 min for elution. The gas chromatographic response is linear with increased concentration of capsaicinoids
Enzyme-Linked Immunosorbent Assay of Benomyl and Thiabendazole in Some Foods
Authors: Newsome Harvey W , Collins Peter G
Published: February 2020

Enzyme-linked immunosorbent assays were developed for benomyl as its decomposition product, methyl 2-benzimidazoIe carbamate, and thiabendazole in foods. Immunogens consisting of human serum albumin coupled to 2-succinamidobenzimidazole or 2-{2'-succinamido- 4'-thiazolyl)benzimidazole were used in rabbits to raise antisera that were specific for the respective fungicides. Lower limits of quantitation of 0.35 ppm for benomyl and 0.03 ppm for thiabendazole were established without cleanup of the ethyl acetate extract. Recoveries of benomyl from 3 crops spiked at 0.5 to 10 ppm averaged 89% (range 73-109%) and of thiabendazole from 5 crops spiked at 0.1 to 2.0 ppm were 93% (range 81-105%).
Determination By Liquid Chromatography With Electrochemical Detection Of Cysteamine And
Cysteine, Possible Precursors Of /V-Nitrosothiazolidine
Authors: Pensabene John W , Doerr Robert C , Fiddler Walter
Published: February 2020

A method is described that is selective, sensitive, rapid, and accurate for the quantitative measurement in meat products of both cysteamine and cysteine, potential precursors for TV-nitrosothiazolidine (NTHZ) and Ar-nirrosothiazolidine-4-carboxylic acid (NTHZC), respectively. In general, a ground meat sample is homogenized with acetonitrileformate buffer in the presence of dithiothreitol, and then is centrifuged, filtered, and recentrifuged in a disposable microfilter. The thiols are quantitated by liquid chromatography using an amperometric detector equipped with a gold/mercury electrode operated in the oxidative mode. Cysteamine was found in 6 of 20 samples of raw pork belly in concentrations ranging from 150 to 450 ppb, and cysteine was found in all samples in concentrations ranging from 2.4 to 36.5 ppm. Analysis for the thiols and their corresponding nitrosamines— NTHZ and NTHZC—of bacon before and after processing showed no correlation between cysteamine and cysteine levels before processing nor with nitrosamine levels after processing. Liquid chromatography with electrochemical detection was found to be an extremely selective technique to measure the 2 free sulfhydryl compounds in a complex food substrate.
Comparison of Methods for Determination of Lactose (Nonfat Dry Milk) in Meat Products
Authors: Ellis Christopher P , Rand Arthur G
Published: February 2020

Four enzymatic methods were compared with the official AOAC yeast fermentation procedure for determining nonfat dry milk (NFDM) as lactose in meat products. The four enzymatic procedures included a commercially available UV test kit, 2 colorimetric assays using kits prepared in the laboratory, and a commercially available instrument with an immobilized enzyme electrode to detect lactose electrochemically. The enzyme procedures were compared with the AOAC method in terms of analysis time, accuracy, precision, sensitivity, specificity, and ease of performance. The UV kit and immobilized enzyme electrode appeared to be the most promising alternatives to the AOAC method on the basis of statistical data and analysis time. Particular needs of a laboratory would dictate the method of choice, but either one could be used as a screening procedure for regulatory purposes. Samples containing levels of NFDM in excess of 3.5% by weight could then be verified by the AOAC yeast method.
Sample Accountability Quality Assurance for the "Integrated Air Cancer Project" Research
Program of the U.S. Environmental Protection Agency
Authors: Watt Randall R , Cupitt Larry T
Published: February 2020

A sample accountability quality assurance (QA) program is described for a field and laboratory research effort which resulted in collection of approximately 2000 samples for analysis by several EPA and contractor laboratories. A QA program was specifically developed for this research program to include sample transfer from collection site to storage maintenance, record development, transfer to researchers, and sample tracking at all stages. A sample identification system and sample custody records are described for field and laboratory application. The functions of a sample coordinator are also described as relating to sample custody, coordination of sample analysis with researchers, and development of computer record files to facilitate research and sample tracking.
Determination of Aspirin and Salicylic Acid by Reverse-Phase Liquid Chromatography
Authors: Heidemann Dorothy R , Schulenberg Edward S , Smith William H
Published: February 2020

Buffered solid dosage forms containing aspirin, magnesium hydroxide, and aluminum hydroxide are blended with acidic ethanol to extract the aspirin and salicylic acid rapidly. The resulting preparation is then immediately injected onto a 4.6 mm x 3 cm 5 (im reverse-phase column. Aspirin and free salicylic acid are determined simultaneously. The run time is <2 min. The total time from the initiation of sample extraction to completion of the separation is <5 min.
Determination of Terbutaline Sulfate in Dosage Forms by Liquid Chromatography with Electrochemical Detection
Authors: Childress William L
Published: February 2020

A liquid chromatographic method with electrochemical detection has been developed for the determination of terbutaline sulfate in dosage forms. A cyanopropyl bonded-phase column is used with a mobile phase consisting of methanol-O.lM monobasic potassium phosphate containing 0.1M sodium heptanesulfonate and ImM disodium ethylenediaminetetraacetate (15 + 85). The compound of interest is detected at a glassy carbon electrode held at a potential of +0.9 V vs silver-silver chloride. The response is linear from 0 to 10 /«g/mL terbutaline sulfate. The method is applicable to tablet composites, individual tablets, dissolution determinations, and injections. Results and supporting data are reported for the above analyses.
Liquid Chromatographic Determination of Levodopa and Levodopa-Carbidopa in Solid
Dosage Forms: Collaborative Study
Authors: Ting Susan
Published: February 2020

A liquid chromatographic method for the determination of levodopa in tablets and capsules and levodopa-carbidopa in tablets was collaboratively studied by 6 laboratories. Collaborators were supplied with duplicate powdered composites of levodopa (1 synthetic formulation, 1 commercial tablet, and 1 commercial capsule) and levodopa- carbidopa (1 synthetic formulation and 2 commercial tablets), along with individual levodopa-carbidopa tablets for content uniformity determinations. The repeatability coefficient of variation (CV„) and reproducibility coefficient of variation (CV„) for levodopa single component were 0.48 and 0.87%; for levodopa in combination, 0.50 and 0.90%; and for carbidopa, 0.77 and 1.20%, respectively. Overall, the recovery values for levodopa and carbidopa from synthetic formulations simulating tablets were 100.4 and 99.5%, respectively .The pooled CVD„ and CVDX values for the individual tablet assays were 2.07 and 2.30% for levodopa, and 1.80 and 2.24% for carbidopa, respectively. The method has been adopted official first action for determination of the active ingredients in levodopa tablets and capsules and in levodopa-carbidopa tablets and for content uniformity testing in the combination dosage form.