bluuebunny/crossref_metadata_2025 huggingface dataset:
Cigarette Smoke Composition. Part 1. Limitations of FTC Method When Applied to Cigarettes That Heat Instead of Burn Tobacco
Authors: Borgerding Michael F , Hicks Richard D , Bodnar James E , Riggs Dennis M , Nanni Edward J , Fulp George W , Hamlin William C , Giles J A
Published: February 2020

The design of a new cigarette that heats rather than burns tobacco calls for modifications to the Federal Trade Commission (FTC) method for analytical smoking. These changes Include eliminating sample conditioning at 75 °F and 60% RH, exercising greater care In lighting cigarettes, and smoking cigarettes to self-extinguishment rather than to a predetermined butt length as a measure of complete consumption. By several gross analytical measures, smoke condensate from the new cigarette differs substantially from that of tobacco-burning cigarettes. This Is Inferred from the lack of coloration of smoke condensate collected on Cambridge filters. Elemental analysis demonstrates reduced carbon and nitrogen content concurrent with Increased hydrogen. Thermogravlmetrlc analysis shows almost quantitative weight loss at Tmax = 220 °C. Ultraviolet (UV) spectrophotometrlc analysis shows greatly reduced levels of tobacco-derived smoke components and qualitative differences In chemical entitles being measured. By design, the heat required for smoke formation Is supplied by a carbon heat source embedded In the cigarette tip. Tobacco contained In the cigarette Is not burned and Is exposed to temperatures less than 300 °C. Thus, It Is apparent (1) that smoke from the new cigarette contains little or no "tar" as tar Is classically defined, and (2) that the FTC method even as modified to account for cigarette design differences Is appropriate only for determination of nicotine and carbon monoxide yielded from this cigarette.
Cigarette Smoke Composition. Part 2. Method for Determining Major Components in Smoke of Cigarettes that Heat Instead of Burn Tobacco
Authors: Borgerding Michael F , Milhous L Arthur , Hicks Richard D , Giles J A
Published: February 2020

A method Is described for determining major constituents In the smoke of a cigarette that heats, but does not burn, tobacco. Dual, simultaneous separations are performed in a single gas chromatographic oven to determine water, glycerol, nicotine, and propylene glycol in a rapid and cost-effective manner. A materials balance of new cigarette smoke total particulate matter was attempted from both Cambridge filter and electrostatic precipitation smoke collection data. Serious deficiencies were found when Cambridge filter smoke collection was applied for this purpose. Electrostatic precipitation smoke collection eliminated these problems. The data obtained by electrostatic precipitation smoke collection Indicate that water, glycerol, nicotine, and propylene glycol make up about 94% of new cigarette smoke total particulate matter.
Rapid Method for Determination of Leucogentian Violet in Chicken Fat by Liquid Chromatography with Electrochemical Detection
Authors: Munns Robert K , Roybal Jose E , Hurlbut Jeffrey A , Shimoda Wilbert
Published: February 2020

The metabolite leucogentian violet (LGV) was found In chicken fat obtained from chickens dosed with gentian violet (GV); however, no residues of the parent compound, GV, and Its oxidized metabolites were found. Therefore, a rapid method was developed for the specific determination of LGV In chicken fat. Chicken fat containing LGV Is separated from the cellular protein with methylene chloride. LGV Is then separated from the fat by partition extraction with an aqueous acid phase In which LGV Is protonated, and the fat Is discarded with the methylene chloride layer. The aqueous solution Is neutralized, LGV Is re-extracted Into methylene chloride, and the methylene chloride Is evaporated. An acetonltrlle- water solution containing LGV Is filtered before liquid chromatography using a cyano column, an acetate buffer- acetonltrile mobile phase, and an electrochemical detector set at a potential of +1.000 V. Average recoveries of LGV from chicken fat were 83.9% with a coefficient of variation (CV) of 12.9 % for the 5 ppb level; 82.8 % with a CV of 13.5 % for the 10 ppb level; and 77.7 % with a CV of 2.56 % for the 20 ppb level. Levels of Incurred LGV in chicken fat averaged 49.3 ppb with a CV of 2.43%
Typical Phthalate Ester Contamination Incurred Using EPA Method 8060*
Authors: Lopez-Avila Viorica , Milanes June , Constantine Franklin , Beckert Werner F
Published: February 2020

Methods for determination of trace levels of phthalate esters In environmental samples require procedures that avoid the Introduction of laboratory contaminants. Because It Is difficult to avoid contamination of samples with phthalate esters from laboratory reagents, materials, and glassware, we have undertaken a study to determine the sources, extent of contamination, and conditions under which background contamination can be minimized. Solvents such as acetone, hexane, diethyl ether, isooctane, and methylene chloride, and reagent water samples from various commercial suppliers were analyzed for 11 phthalate esters. Florlsll, alumina, silica gel, anhydrous sodium sulfate, filter paper, paper thimbles, glass wool, and aluminum foil were washed with organic solvents and the solvent washings were analyzed for 11 phthalate esters. Finally, we addressed the likelihood of contamination of laboratory glassware subjected to common laboratory cleanup procedures and the likelihood of contamination of hexane and Isooctane stored In sample vials of different sizes. The present study was conducted in conjunction with the single-laboratory evaluation of U.S. Environmental Protection Agency (EPA) method 8060 for determination of phthalate esters in environmental samples.
Gas Chromatographic Determination of Systemic Fungicide Tricyclazole in Soil and Water
Authors: Yunxiang Xiao , Defang Fan , Hexin Chen
Published: February 2020

A method Is described for determination of tricyclazole residues In soil and water. Tricyclazole is extracted from soil by refluxlng with ethyl acetate-acetone (80 + 20 v/v) and from water by partitioning Into dlchloromethane. The soil extract Is purified by coagulation. The compound Is detected and measured by gas chromatography using a flame photometer operated In the sulfur mode. Detection limits are 8 ppb for soil and 0.8 ppb for water. Recoveries for control samples fortified with tricyclazole at 0.1-5.0 ppm averaged 97.1 % for soil and 108.1% for water.
Simple Analytical Method for Organophosphorus Pesticide Residues in Milk
Authors: Toyoda Masatake , Adachi Kazuhiko , Ida Tadakazu , Noda Katsuhiko , Minagawa Norio
Published: February 2020

A simple method for determination of organophosphorus pesticide residues at the parts per million level In milk was developed. Pesticide residues were extracted with acetonitrlle added to aqueous milk, fat was removed by zinc acetate addition and dichloromethane partition, and analytes were concentrated and analyzed by wide-bore capillary column gas chromatography. Recoveries of 6 pesticides spiked in milk samples at levels of 0.1 and 1.0 μg/mL were 82.1- 93.8% and 79.7-96.6%, respectively. Triplicate samples spiked with 6 pesticides at 1 itg/mL were analyzed independently by 3 laboratories. Average recoveries were greater than 80%, and the mean coefficients of variation for the complete study were 2.9% for diazlnon, 5.4% for dimethoate, 4.6% for malathlon, 4.6% for parathlon, 4.9% for EPN, and 6.1% for phosalone.
Development of Milk Powder Reference Materials BCR-CRM 187,188. Part I. Preparation, Homogeneity, and Stability
Authors: Quirijns Jan K , Van Der Paauw Kees G , Mulders Ed J , Griepink Bernard
Published: February 2020

Two milk powders were prepared and tested as reference materials for 9 organochlorlne pesticides and metabolites: hexachlorobenzene, HCH Isomers (a-HCH, jS-HCH, 7-HCH), 0-heptachlor epoxide, dleidrin, endrln, p.p'-DDE, and p,pf- DDT. The reference materials, a natural milk powder (CRM 187) and a spiked milk powder (CRM 188), contain the analytes at concentrations of 1.5 to 69 /ig/kg on a dry weight basis. Preparation and testing for homogeneity and stability of the powders are discussed. The mean coefficient of variation In the homogeneity tests was about 4.5%, which indicates that the homogeneity of the samples Is very good. Stability data over 12 months do not show any trend that suggests lack of stability
Homogenization Methods for Analysis of Foodstuffs
Authors: Lichon Michael J , James Keith W
Published: February 2020

Methods for homogenlzatlon of food matrixes are examined. Determinations Involving foods homogenized by noncryogenlc methods were found to have relative standard deviations varying Inversely with the subsample mass used for determination. Each method could only be used for sampling at the milligram level on a very limited range of foods. Cryogenic homogenlzatlon methods were effective on the majority of foods, allowing milligram subsample masses to be used for analysis. A noncryogenlc pretreatment was generally necessary to obtain a subsample suitable for cryogenic homogenlzatlon
Determination of Pentachlorophenol in Animal Tissues: A Canadian Perspective
Authors: Macneil James D , Patterson John R , Fesser Adrian C , Martz Valerie K
Published: February 2020

Analytical methods for pentachlorophenol (PCP) residues In edible animal tissue have been reviewed, with particular reference to gas chromatographic methods of analysis. Results of analyses demonstrate that significant residues of PCP can persist for several weeks In animals exposed to contaminated bedding. National surveys In Canada have found that the incidence of PCP residues In pork in excess of 0.1 ppm was reduced from 32% of survey samples In 1981- 1982 to 6.6% of samples tested In 1987-1988. An Interlaboratory sample exchange among Canadian laboratories demonstrated that the PCP analytical method currently used by Agriculture Canada could be successfully transferred to other laboratories. An exchange of samples between regulatory laboratories of Agriculture Canada and the Food Safety and Inspection Service of the U.S. Department of Agriculture (USDA) demonstrated equivalency of results for the 2 methods currently used in the respective laboratories, with relative standard deviations for analytical results ranging from 4.4 to 22.2%.
Matrix Solid Phase Dispersion Isolation and Liquid Chromatographic Determination of Oxytetracycline in Catfish (Ictalurus punctatus) Muscle Tissue
Authors: Long Austin R , Hsiesh Lily C , Malbrough Marsha S , Short Charles R , Barker Steven A
Published: February 2020

A method for Isolation and liquid chromatographic determination of oxytetracycllne In catfish (Ictalurus punctatus) muscle tissue Is presented. Blank control and oxytetracycllne- fortlfied fish muscle tissue samples (0.5 g) were blended with octadecylsilyl (C18, 40 μm, 18% load, endcapped) derlvatized silica packing material (2 g) containing 0.05 g each of oxalic acid and disodlum ethylenedlamlnetetraacetate. A column made from the C18/fish tissue matrix was first washed with hexane (8 mL), following which the oxytetracycllne was eluted with acetonltrile-methanol (1 + 1, v/v) containing 0.06% w/v each of butylated hydroxyanlsole and butylated hydroxytoluene. The eluate contained oxytetracycllne analyte that was free from Interfering compounds when analyzed by liquid chromatography with UV detection (photodlode array set at 365 nm). Standard curves for oxytetracycllne Isolated from fortified samples were linear (0.998 ± 0.002) with an average absolute percentage recovery of 80.9 ± 6.6% for the concentration range (50,100,200, 400, 800, 1600, and 3200 ng/g) examined. The Interassay variability was 11.3 ± 5.2% with an Intra-assay variability of 1.1%.
Liquid Chromatographic Determination of Cephapirin Residues in Milk
Authors: Macintosh Agnes I
Published: February 2020

A liquid chromatographic (LC) method was developed for quantitative determination of cephapirin residues In milk that also resolved cephapirin from amplcillln, cloxaclllin, and penicillin G. Diluted milk was passed through a C18 cartridge on which the cephapirin was adsorbed; then, Interfering material was removed by washing with water and methylene chloride and cephapirin residues were eluted with methanolacetonitrlle (25 + 75). After drying, residues were dissolved in the mobile phase for Injection. The LC system had an ultrasphere-ODS column with RP-18 Spherl-10 guard column and a UV detector with a 254 nm filter. The mobile phase was 85% sodium acetate (0.01M) and 15% methanol-acetonltrile (25 + 75) with a flow rate of 1 mL/mln. Sensitivity was 20 ppb or less with a recovery of 61-80% in the range studied. Other βlactam antibiotics tested did not Interfere with detection of cephapirin. Analysis of 30 samples of commercial homogenized milk obtained for a survey of antibiotics in consumer milk In Canada revealed no detectable cephapirin residues.
Gas Chromatographic-Mass Spectrometric Determination of Six Sulfonamide Residues in Egg and Animal Tissues
Authors: Takatsuki Keigo , Kikuchi Tadashi
Published: February 2020

A gas chromatographlc-mass spectrometric method using selected Ion monitoring mode for simultaneous determination of 6 sulfonamides in egg and edible animal tissues has been developed. Sulfonamides are extracted from a sample with acetonltrlle. The extract Is passed through a silica cartridge column and concentrated. Dlazomethane in ether Is added to methylate sulfonamides. After evaporation, the residue Is dissolved In methylene chloride and cleaned up by silica gel column chromatography. The methylene chloride eluate containing sulfonamide-methyl derivatives Is evaporated to dryness, redlssolved In ether and partitioned between 6N hydrochloric acid. The acid phase is made alkaline, extracted with ether, and the ether solution, after concentration, Is analyzed by gas chromatography-mass spectrometry in selected Ion monitoring mode. Average recoveries from egg and silver salmon fortified at 1 and 0.2 ppm levels with 6 sulfonamides are 99.2 and 84.3%, respectively; coefficients of variation are 7.03 and 11.20%, respectively. Detection limits are 0.01-0.05 ppm.
Determination of Ivermectin in Medicated Swine Feeds at the 2 ppm Concentration Level
Authors: Doherty Stephen J , Fox Allen , Fink David W
Published: February 2020

An analytical method has been developed that Is applicable to the determination of Ivermectin in medicated feeds at the 2 ppm concentration level. It Is based upon liquid chromatographic analysis with a reverse-phase column and ultraviolet detection. After the drug Is extracted from the feed Into methanol, an analytical sample Is prepared by the consecutive use of column chromatography on alumina and solidphase extraction on Sep-Pak C18 and silica cartridges. This procedure has been applied to the concentration range 0.50- 3.0 ppm of Ivermectin In feed with an accuracy of ±2% mean relative error and a precision of ± 2% relative standard deviation at the 2 ppm concentration level.
Design And Analysis Of Qualitative Collaborative Studies: Minimum Collaborative Program
Authors: Mcclure Foster D
Published: February 2020

Collaborative studies Involving qualitative data are usually conducted under design constraints to fulfill the requirements for quantitative studies. The data from these qualitative studies are often analyzed In a manner that ignores the fact that collaborative studies Involve matching (I.e., each laboratory analyzes a portion of each test sample). This report presents some design considerations and analysis procedures for qualitative collaborative studies that take into account that the design Involves matching. Suggestions are offered as to the number of laboratories and test samples to use in the minimum collaborative program, and analysis procedures for outlier screening are detailed. Method performance Is assessed through such Indicators as sensitivity, specificity, false positive, and false negative rates. Methods for estimating the error of the performance indicator rates are explained, and procedures are given for estimating false positive and false negative rates for lot defect rates that may occur In practice.
Colorimetric and Fluorometric Substrate Immunoassays for Detection of Salmonella in All Foods: Comparative Study
Authors: Curiale Michael S , Joan Klatt Mary , Gehle Warren D , Chandonnet Heidi E
Published: February 2020

Two modified fluorescent enzyme Immunoassays for the detection of Salmonella In food have been developed. Both of the new procedures, which substitute a colorimetric substrate for the fluorescent substrate and In which results are read visually or with a photometer, are modifications of AOAC method 989.15. The visually read procedure uses the same antibody-coated wells as In method 989.15. The colorimetric end point of the assay is determined by comparing the solution color to a color chart. The assay result may also be read in a photometer, If the solution is first transferred to a transparent mlcrotiter well. The second procedure designed to be read in a photometer substitutes clear, antibody-coated wells for those used In the fluorescent assay. The colorimetric assays employ Identical monoclonal antibodies for capture and detection of Salmonella as used in the fluorescent assay. In this comparative study, the performance of each new assay was consistent with the performance of method 989.15. These methods have been adopted official first action by AOAC as alternative methods for the detection of Salmonella in foods.
Atomic Absorption Spectrophotometric Determination of Calcium and Magnesium and Colorimetric Determination of Phosphorus in Cheese: Collaborative Study
Authors: Pollman Roger M
Published: February 2020

The determination of calcium, phosphorus, and magnesium In cheese was collaboratively studied. The sample is dried and ashed and the residue is dissolved In an acidified aqueous solution. Calcium and magnesium are determined by atomic absorption spectrophotometry and phosphorus Is determined by colorlmetry. The study was repeated 3 times because of high within- and between-laboratory relative standard deviations (RSDr and RSDR, respectively). Poor precision In the first 2 studies was caused by a number of factors, Including use of contaminated glassware, Improperly maintained Instruments, and Impure reagents as standards. In each study, 5 varieties of cheese were distributed as 10 blind duplicate samples along with a practice sample. Thirteen laboratories participated in the third study, which was generally problem-free. The range of results and the average RSDr and RSDR found In the cheeses were: calcium, 608- 1107 mg/100 g, 1.5%, 2.6%; magnesium, 23.9-50.6 mg/ 100 g, 2.8%, 3.8%; phosphorus, 444-695 mg/100 g, 1.2%, 1.6%. The method has been adopted official first action by AOAC.
Liquid Chromatographic Multicomponent Method for Determination of Residues of Ipronidazole, Ronidazole, and Dimetridazole and Some Relevant Metabolites in Eggs, Plasma, and Feces and Its Use in Depletion Studies in Laying Hens
Authors: Aerts Rene M L , Egberink Irma M , Kan Cornelis A , Keukens Henk J , Beek Wim M J
Published: February 2020

A simple, rapid liquid chromatographic (LC) method that uses UV/VIS detection has been developed for the determination In eggs of residues of the hlstomonostats dlmetridazole (DMZ), ronldazole (RON), Ipronidazole (IPR), and side-chain hydroxylated metabolites of DMZ and RON. Sample pretreatment Includes an aqueous extraction, purification with an Extrelut® cartridge, and acid partitioning with Isooctane. An aliquot of the final aqueous extract Is Injected Into a reversephase LC system; detection Is performed at 313 nm. The limits of determination are in the 5-10 µgkg range. A UV/ VIS spectrum can be obtained at the 10 µg/kg level by using diode-array UV/VIS detection. Recoveries are between 80 and 98% with a coefficient of variation of about 5%. Some 20 samples can be analyzed per day. A side-chain hydroxylated metabolite of IPR can also be detected with this method, as demonstrated with samples from animal experiments. After a single oral dose of the drugs to laying hens, residues of the parent compound and/or the hydroxylated metabolites could be detected In eggs 5-8 days after dosing. Plasma distribution and excretion in feces were established both with and without deconjugatlon. DMZ and IPR were extensively metabolized to hydroxylated nltrolmldazole metabolites; RON was excreted mainly as the parent compound.
Liquid Chromatographic Determination of Aflatoxin Levels in Peanut Butters Using an Immunoaffinity Column Cleanup Method: International Collaborative Trial
Authors: Patey Alan L , Sharman Matthew , Gilbert John
Published: February 2020

Thirteen laboratories In 7 different countries participated in a collaborative trial to evaluate an Immunoaffinity column cleanup procedure with quantitation by fluorescence liquid chromatography (post-column derivatization) for the determination of aflatoxins In peanut butters. Participants were sent 10 randomly numbered samples of roasted peanut butter for analysis (5 pairs of undisclosed duplicates). Two of the pairs were "blank" peanut butters to which aflatoxin standards had been added; these "spiked" samples were used for recovery purposes. The other 3 pairs of samples were a nominal "blank" and 2 naturally contaminated peanut butters. A full statistical presentation of the results is given. Coefficients of variation (CVs) for the total aflatoxin determinations for mean levels of 4,15, and 38 µ/kg were between 32 and 44% for the blank and 2 trial samples. Recovery levels for the 2 spiked samples were 51-67%, with aflatoxin B1 recovery of 60%. Relative standard deviations for method repeatability (RSDr) and reproducibility (RSDR) for the 3 trial samples were 15-26% and 33-45%, respectively.
Immunoaffinity Column Coupled with Solution Fluorometry or Liquid Chromatography Postcolumn Derivatization for Determination of Aflatoxins in Corn, Peanuts, and Peanut Butter: Collaborative Study
Authors: Trucksess Mary W , stack Michael E , Nesheim Stanley , Page Samuel W , Albert Richard H , Hansen Thomsen J , Donahue Kevin F
Published: February 2020

An AOAC/IUPAC (International Union of Pure and Applied Chemistry) collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column for the determination of af latoxin. The test portion Is extracted with methanol- water (7 + 3), filtered, diluted to ⦟30% methanol with water, and applied to the affinity column. The column Is washed with water and the concentrated aflatoxins are eluted with methanol. Total aflatoxins are determined by solution fluorometry with bromine (SFB), and Individual toxins are determined by reverse-phase liquid chromatography with postcolumn derlvatizatlon with Iodine (PCD). Corn naturally contaminated with aflatoxins, and peanuts, peanut butter, and corn containing added aflatoxins ( B1:B2:G1G2 = 7:1:3:1) were sent to 24 collaborators In the United States, France, Canada, and the Republic of South Africa. Twelve collaborators used the SFB method, 9 used the PCD method, and 3 used both SFB and PCD methods. Twenty collaborators completed the study (10 used the SFB method, 7 used the PCD method, and 3 used both SFB and PCD methods). Test portions were spiked at 10, 20, and 30 ng/g. For SFB analyses, recoveries of total aflatoxins were 123,105, and 107%, respectively; the relative standard deviation for repeatability (RSDr) ranged from 11.75 to 16.57%, and the relative standard deviation for reproducibility (RSDR) ranged from 10.97 to 33.09%. For PCD analyses, recoveries were 81, 81, and 83%, respectively; the RSDr ranged from 5.20 to 17.22%, and the RSDR ranged from 4.68 to 50.77%. The RSDr for aflatoxins B1, and G1 for spiked test portions ranged from 5.45 to 23.55%, and the RSDR ranged from 4.21 to 57.28%. The RSDr and RSDR for aflatoxins B2 and G2 were higher because of the small amounts added. Analyses by both SFB and PCD methods showed acceptable within-laboratory and betweenlaboratories precision. The method has been adopted official first action by AOAC as an AOAC-IUPAC method.
Determination of Dioxins and Furans in Foods and Biological Tissues: Review and Update
Authors: Firestone David
Published: February 2020

Determination of trace residues of polychlorlnated dlbenzo- p-dloxlns and dibenzofurans (PCDDs and PCDFs) In various matrixes Is carried out by a limited number of laboratories In the United States, Canada, and other countries. Current methods for analysis of foods and biological tissues Include a combination of preparation, extraction, cleanup, isolation, determination, and Identity confirmation procedures. Soxhlet, liquid/liquid, solid-phase, and column extraction procedures are used as well as treatment with acid or base before solvent extraction. Cleanup and isolation steps Include sulfuric acid partitioning; adsorption chromatography on Florlsil, silica gel, or alumina; gel permeation chromatography; multistage column chromatography on sulfuric acid silica and alkali silica; carbon column chromatography; and liquid chromatography fractionation with size exclusion, normalphase, and reverse-phase columns. Activated carbon and multistage chromatographic columns are widely used in cleanup schemes. Isomer-speclflc Identification and quantitation of PCDD and PCDF congeners at parts-per-trllllon levels or lower are carried out by high resolution (capillary) gas chromatography (HRGC) and multiple Ion detection mass spectrometry. In addition to chemical methods, bloassay procedures have been recommended (e.g., use of monoclonal antibodies, for immunoassay determination of PCDDs and PCDFs).
Determination of Nabam Fungicide in Crops by Liquid Chromatography with Postcolumn Reaction Detection
Authors: Miles Carl J , Zhou Min
Published: February 2020

The ethyleneblsdlthlocarbamate (EBDC) fungicide, nabam, was determined In several crop matrixes using liquid chromatography with postcolumn reaction detection. After separation by mlcellar liquid chromatography, nabam (EBDC sodium salt) was acid hydrolyzed to ethylenedlamlne and fluorogenlcally labeled with o-phthalaldehyde-mercaptoethanol (OPA-MERC). Standard curves were linear from the detection limit of ca 1 ng to 1000 ng. Nabam was recovered In high yield (89 ±7.7%) over a range of concentrations (0.1 to 20 ppm) from fortified samples of papaya, lettuce, cucumber, spinach, and applesauce using a simple extraction method. Efforts to convert the more popular EBDC fungicides, maneb and mancozeb, to nabam are discussed.
Determining Organohalides in Animal Fats Using Gel Permeation Chromatographic Cleanup: Repeatability Study
Authors: Goodspeed Donald P , Chestnut Larry I
Published: February 2020

Evaluation of a previously published gel permeation chromatographic (GPC) procedure was undertaken to determine whether It can be used for additional organochlorine pesticides. After repeatability studies of many pesticides, the following compounds were approved for Inclusion in the U.S. Department of Agriculture Domestic Residue Monitoring Program: coumaphos-S, stirophos, chlorpyrlfos, ronnel, carbophenothlon, chlorfenvlnphos, phosalone, kepone, captan, llnuron, and endosulfan I and II. Recoveries ranged from 54% for captan to 123% for ronnel. Ranges of CVs varied from 0- 9.5% for carbophenothion to 7.1-47.7% for kepone. Although the minimum acceptable recovery of 50% was attained for all 12 pesticides, the anticipated CV of 20% was waived to Include chlorpyrlfos, endosulfan I and II, and kepone. For a multlresidue procedure involving approximately 40 compounds, these results were within the acceptable criteria.
Liquid Chromatographic Determination of Clidinium Bromide and Clidinium Bromide-Chlordiazepoxide Hydrochloride Combinations in Capsules
Authors: Yuen Stella M , Lehr Gary
Published: February 2020

A specific liquid chromatographic method was developed for determination of clidinium bromide and clidinium bromidechlordiazepoxide hydrochloride combinations in capsules. The procedure uses a Partisil 10 ODS-3 column and a mobile phase consisting of acetonitrile-0.3M ammonium phosphate (32 + 68) (pH = 4.3). The detection wavelength is 235 nm. Accuracy, reproducibility, and linearity were within accepted criteria. Four commercial samples of the single ingredient were tested; results compared favorably with the compendial method. Two commercial samples of the combination product were tested by the proposed method and results reported. The system was found to be free from any interferences from the 4 known related compounds of the 2 major components and Is useful as a screening procedure for 7- chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one- 4-oxide, the principal degradation product of chlordiazepoxide hydrochloride.
Determination of Penicillin G Residues in Edible Animal Tissues by Liquid Chromatography
Authors: Boison Joe O , Salisbury Craig D C , Chan Wayne , Macneil James D
Published: February 2020

An Improved method has been developed for the determination of benzyl penicillin In animal tissues. Tissues are fortified with a known amount of penicillin V (Internal standard) and extracted with water. The extract Is deproteinlzed with sulfuric acid and sodium tungstate, filtered, and concentrated on a conditioned C18 solid phase extraction column. Penicillin V and benzyl penicillin are then eluted from the column with 1 mL 60% acetonitrile-35% water-5% 0.2M phosphate buffer solution and derivatlzed with 1 mL 1,2,4-trlazole-mercuric chloride solution at 65°C for 30 min. An aliquot of this sample Is analyzed by reverse phase liquid chromatography with UV detection at 325 nm. The limit of detection is 5 μg/kg (ppb) penicillin G (8.4 lU/kg) In liver, kidney, and muscle tissues
Quantitative Analysis of Limonin in Grapefruit Juice Using an Enzyme-Linked Immunoassay: Interlaboratory Study
Authors: Widmer Wilbur W , Rouseff Russell L
Published: February 2020

Eleven laboratories participated in an interlaboratory study of an enzyme-linked immunoassay for limonin in grapefruit Juice. Participating laboratories received training and practice samples until familiar with the procedure. Laboratories then received 8 sample pairs of grapefruit Juice as blind duplicates. Samples were refrigerated and analyzed within 4 days of receipt. Results from 1 laboratory and 6 Individual samples were excluded from the statistical analysis. Method performance was measured by the one-way component of variance analysis. Repeatability relative standard deviations (RSDr) ranged from 7.0 to 15.6%. Reproducibility relative standard deviations (RSDR) ranged from 12.9 to 29.4%
Quantitative Determination of Mono- and Diglycerides with and without Derivatization by Capillary Supercritical Fluid Chromatography
Authors: Lee Theresa W , Bobik Emil , Malone William
Published: February 2020

Mono- and diglycerides, as well as commercial monoglyceride emulsifiers, were analyzed by capillary supercritical fluid chromatography (SFC). Carbon dioxide without modifier was used as the mobile phase in the chromatography. Samples were prepared by simply being dissolved in solvents or by propionyl ester derivatization. A capillary SFC methyl silicone column (SB-methyl 100, 100 μm X 10 m, 0.5 μm film thickness, Lee Scientific) was used for the separation, and a flame ionization detector was used for the detection. A calibration standard containing known concentrations of monomyristln, monopalmitin, monostearin, dimyristin, dlpalmitin, and distearin were used for the determination of the response factor (unit weight per peak area) of each analyte. The response factors were used in the quantitation of the analytes in the test samples from their respective integrated peak areas. Monomyristin was used as an internal standard for the quantitation of monoglycerides In commercial emulsifiers. The accuracy of the methods was demonstrated by comparing the percent area (%A) determined by the chromatography with the percent weight (%W) of each of the components in the standard mixture, and the precision of the methods was indicated by the relative standard deviation (RSD). The mean ratio and RSD of %A/%W were 0.98 ± 0.09 (<5%) and 1.01 ± 0.03 (<2.5%) for underlvatized and derivatized samples, respectively. Two lots of commercial monoglyceride emulsifiers were analyzed with and without derivatization, and the results were compared to those obtained by gas chromatography (GC). 7-tests comparing the method means did not indicate any significant mean differences (95% confidence level) between the GC and SFC methods. Nor did the variance ratio F-test indicate that the overall variances of the methods were significantly different. However, the error variance of the SFC-underivatized method was significantly higher than that of the GC and SFCderivatized methods. These results demonstrated the feasibility of applying the SFC technology in the analysis of monoand diglycerides with and without derivatization
Zinc Chloride-Diphenylamine Reagent for Thin Layer Chromatographic Detection of Some Organophosphorus and Carbamate Insecticides
Authors: Sevalkar Murlidhar T , Patil Vitthal , Katkar Harischandra N
Published: February 2020

Zinc chlorlde-diphenylamlne reagent, whose use has been reported for the detection of organochlorine insecticides by thin layer chromatography, was further studied for its ability to detect the organophosphorus insecticides phorate, phosphamldon, DDVP, and phosalone and the carbamate Insecticides carbaryl and aldicarb. These Insecticides give Intense blue-green spots with this reagent. The procedure can be applied to the detection of the insecticides in biological materials and thus has a potential use in forensic toxicology
Comparison of Microwave Digestion with Conventional Wet Ashing and Dry Ashing Digestion for Analysis of Lead, Cadmium, Chromium, Copper, and Zinc in Shellfish by Flame Atomic Absorption Spectroscopy
Authors: McCarthy Helen T , Ellis Christopher P
Published: February 2020

A closed vessel microwave digestion procedure was developed for shellfish samples. This procedure was compared with wet and dry ash procedures for levels of lead, cadmium, chromium, copper, and zinc. Results obtained for microwave and conventional wet ash digestion were comparable. The dry ashing procedure produced results consistently lower than either of the other methods. Recoveries ranged from 80-92% for microwave and wet ashing procedures and 54- 72% for the dry ashing procedure. Accuracy was also determined by analyzing lobster hepatopancreas marine reference material. Values for Pb, Cd, and Cr fell within the range specified for the reference material for all 3 digestion procedures; however, values were lower for Cu and Zn. Results of this study show that microwave digestion is comparable to wet ashing.
Improved Selenium Recovery from Tissue with Modified Sample Decomposition
Authors: Brumbaugh William G , Walther Michael J
Published: February 2020

The present paper describes a simple modification of a recently reported decomposition method for determination of selenium In biological tissue by hydride generation atomic absorption. The modified method yielded slightly higher selenium recoveries (3-4%) for selected reference tissues and fish tissue spiked with selenomethionine. Radiotracer experiments indicated that the addition of a small volume of hydrochloric acid to the wet digestate mixture reduced slight losses of selenium as the sample initially went to dryness before ashing. With the modified method, selenium spiked as selenomethionine behaved more like the selenium in reference tissues than did the inorganic spike forms when this digestion modification was used
Determination of Polydextrose (Polymer) and Residual Monomers in Polydextrose by Liquid Chromatography
Authors: Thomas John W , Brown Donna L , Hoch Daniel J , Leary John J , Dokladalova Jarmila
Published: February 2020

A simple, liquid chromatographic method has been developed for determination of the reduced-calorie food additive polydextrose—a water soluble, 1 kilocalorie/gram bulking agent used extensively for manufacture of low-calorie food products. The method allows rapid determination of polydextrose content as well as determination of the minor components: dextrose, sorbitol, and 2 isomeric anhydroglucoses in bulk samples of polydextrose. The proposed method is superior to current Food Chemical Codex (FCC) methodologies for determination of polydextrose (phenol sulfuric acid spectrophotometry) and for determination of residual monomers [gas chromatographic (GC) determination as their trimethylsilyl derivatives]. The proposed method is more precise, considerably faster, and is safer to execute. The method uses a resin-based cation exchange column, 0.001N sulfuric acid mobile phase, and differential refractive index detection. Analyte response curves were linear; and data displayed good precision with coefficients of variation ranging from 1.1 to 1.6%. The efficiency, specificity, precision, and ruggedness of the method make it amenable to implementation in a routine quality control operation.
Capillary Gas Chromatographic Determination with Electron Capture Detector of β-Propiolactone in Biological Materials
Authors: Geahchan Aziz , Fouillet Bruno , Chambon Paul , Chambon Renee , Nouri Bahia
Published: February 2020

A method has been developed for the determination of β- propiolactone by derivatizing it to the volatile N-hexyl-3- heptafluorobutanoyloxypropanamide, which can be separated and Identified by a capillary CP-Sil 8 column, and detected by an electron capture detector (ECD). First, β- propiolactone is reacted with N-hexylamine to yield N-hexyl- 3-hydroxypropanamide. The fluorobutanoyl ester derivative is next prepared by using heptafluorobutyrlc acid anhydride in the presence of trimethylamine. The method Is very sensitive, simple, and specific, and can be used to detect and quantitate residual β-propiolactone In Iyophilized biological materials. The limit of detection is 0.2 ppm β-proplolactone in a 50 mg sample; however, because of variability at low levels, the limit of quantitation is 1 ppm. Detector response was linear for 2-500 ng β-propiolactone. Recoveries were 98% or greater from Iyophilized vaccines spiked at the 2-20 ppm level. No side products or interference peaks were observed in the derivatization reaction.
Comparison of Preston Agar and a Blood-Free Selective Medium for Detection of Campylobacter jejuni in Food
Authors: Peterz Mats
Published: February 2020

The present collaborative study compares recovery of Campylobacter Jejuni from food in 2 agar media. Six laboratories analyzed 8 samples each of chicken liver Inoculated with Campylobacter Jejuni. Samples were enriched in Preston broth and isolation was carried out on Preston agar (PA) and Campylobacter blood-free selective medium (CBFS), a charcoal- based medium with cefoperazone and amphoteracin as antibiotic supplements. There was no difference In the recovery rate between the 2 agar media; however, the specificity of CBFS was better than that of PA. There was a slightly better growth of Campylobacters, and competing organisms were more inhibited on CBFS than on PA.
Immunochromatography of Fusarochromanone Mycotoxins
Authors: Yu Jaehyuk , Chu Fun Sun
Published: February 2020

The present paper describes an enzyme-linked immunoassay (ELISA) used In combination with thin-layer chromatography (TLC) and liquid chromatography (LC) for determination of fusarochromanone (TDP) mycotoxins in barley, wheat, and a Fusarlum culture grown in rice and corn. The mycotoxins were first extracted from the sample with 100% methanol and subjected to TLC or LC without additional cleanup treatment. Individual fractions eluted from TLC or LC were acetylated, then analyzed by ELISA. Determinations of TDP toxins at levels as low as 0.1 and 0.5 ng were achieved by ELISA in combination with LC and TLC, respectively. The detection limit for TDP-1 in barley and wheat was about 20 ppb by ELISA alone as compared with a detection limit of 5 ppb by a combination of ELISA with either TLC or LC. Overall analytical recovery (% of added) of TDP-1 added to barley and wheat at 5,10, and 20 ppb of TDP-1 was 106.9 ± 15.3 and 113.2 ± 11.6 by LC-ELISA and 108.8 ± 9.1 and 110.4 ± 4.9 by TLC-ELISA, respectively. Analysis of extracts obtained from Fusarlum equiseti R6137 grown in corn and rice by the combination of TLC and ELISA revealed that diacetyl-TDP was also produced by this fungus in addition to TDP-1 and TDP-2. Comparable results were obtained when fungal extracts were subjected to ELISA, LC, and immunochromatography (i.e., combination of ELISA with either TLC or LC).
Modified Gas Chromatographic/Mass Spectrometric Method for Determination of Daminozide in High Protein Food Products
Authors: Faughnan Kevin T , Woodruff Marie A
Published: February 2020

A modified version of the Conditt and Baumgardner gas chromatographic/mass spectroscopic (GC/MS) method for determination of daminozide in peanut butter and raw peanuts is described. Daminozide in the food product is hydrolyzed to unsymmetrical dimethylhydrazine (UDMH) by sodium hydroxide digestion. The generated UDMH is distilled from the food matrix and captured by reaction with salicylaldehyde in a condensation trap. Resulting high pH distillates generated by peanuts and peanut products are adjusted back to a pH of 5-6 through addition of glacial acetic acid. After thermal incubation and extraction Into methylene chloride, salicylaldehyde dimethylhydrazone is separated from interferences by capillary GC and quantitated by MS using the selective ion monitoring (SIM) mode. Quantitation of daminozide is based on the ratio of the salicylaldehyde dimethylhydrazone molecular ion (m/z 164) to the molecular ion (m/z 153) of the Internal standard, 4-nitroanisole. Confirmation of daminozide identity is determined by relative Intensity of the m/z 164 Ion to the m/z 120 (C7H4ON) ion. Improved m/z 164 Ion Intensity and reduction of neighboring interferences due to acetic acid treatment permitted a daminozide detection limit of 0.005 ppm in a 50 g sample and an associated 0.02 ppm limit of quantitation. This modification is specific for high protein samples that generate high pH distillates such as peanuts and peanut products and is not specifically intended for analysis of low protein samples.
Listeria monocytogenes
Authors: Farber Jeffrey M
Published: February 2020

Listeria monocytogenes, one of the "new enemies" in food microbiology, is a human and animal pathogen that is widespread in nature. The organism Is a transient constituent of the Intestinal flora excreted by 1-10% of healthy humans. It is an extremely hardy organism and can survive for many years in the cold In naturally Infected sources. L monocytogenes has been Isolated from a wide variety of foods, including dairy products, meats, and fish. Although most of the foodborne listeriosis outbreaks have been linked to the consumption of dairy products, recent sporadic cases have been associated with meats, as well as other foods. It is now recognized that listeriolysln 0, a 60-kilodalton protein, is one of the major virulence factors of the organism. All strains of L monocytogenes are pathogenic by definition although some appear to be more virulent than others. There have been recent reports of hemolytic isolates of L monocytogenes, which are nonpathogenic for mice. Attachment to and penetration of cells also appear to be prerequisites for human infection. Cultural methodology for isolating the organism from foods has been in a state of flux since 1985. Rapid methods using both ELISA and DNA technology have been developed. Because of the widespread nature of the organism, it Is nearly Impossible to eliminate it from the food supply. However, by using a hazard analysis-critical control point approach, the health hazard associated with this organism can be reduced to a minimum.
Quantitation of the Nitrosamine 2-EthylhexyI-4-(N-Methyl-N-Nitrosoamino) Benzoate (NPABAO) in Sunscreen Products
Authors: Meyer Thomas A , Powell Jimmy B
Published: February 2020

We have devised a method to quantitate the nitrosamine, 2- ethylhexyM-(N-methyl-N-nitrosoamino) benzoate (NPABAO), In commercial products containing the sunscreen ingredient, Padimate 0. The method involves a minimum of cleanup steps to afford a nonaqueous extract from product emulsions suitable for analysis by a liquid chromatograph Interfaced to a thermal energy analyzer (LC/TEA). The method Is applicable to lotions, creams, and gels. Oils are normally soluble In the mobile phase and can be analyzed directly on the LC/TEA without additional cleanup procedures. The method has a minimum detectable limit of about 30 ppb and yields > 80% recovery. It is highly reproducible and generates no NPABAO artifactually prior to quantitation on the LC/TEA Application of the method to 22 different commercial product formulas disclosed that the level of NPABAO in each of the products Is below 250 ppb, with 18 of the products containing less than 100 ppb. Of interest was the observation that musk ketone, a common fragrance constituent, produces a false-positive TEA response that can Interfere with accurate analysis of NPABAO content In typical commercial products
Rapid Extraction of Available Phosphorus in Fertilizers
Authors: Trimm Joe R , Farley James A
Published: February 2020

A method for the rapid extraction of available phosphorus In fertilizers Involves a single-step extraction that uses ethylenediaminetetraacetic acid (EDTA) as a complexing agent for Ca and Mg. This complexatlon of Ca and Mg enables the analyst to avoid the preliminary water extraction currently required. Sample extraction Is similar to that in method 963.03B(b),Official Methods of Analysis, 15th Ed. The extractant consists of a solution of dibasic ammonium citrate, disodium EDTA, and ammonium hydroxide. The extract or residue may be analyzed by existing AOAC methods. Results by the new extraction method agree favorably with those by existing methods. Analyses of samples from the Magruder and the Association of Florida Phosphate Chemists check sample programs agreed favorably with reported values for neutral ammonium citrate extraction.
Comparison of an ELISA-based Screening Test with Liquid Chromatography for the Determination of Aflatoxins in Corn
Authors: Beaver Rodney W , James Mary A , Lin Tay Y
Published: February 2020

An enzyme-linked immunosorbent assay (ELISA) screening test (CITE PROBE) was compared to liquid chromatography (LC) for the determination of aflatoxins in naturally contaminated corn samples. The CITE PROBE, with a positive/negative cutoff of 5 ng/g aflatoxin Bi, was correct (based on LC results) on 47 of 51 samples. Two of the Incorrect responses by the CITE PROBE were false positives on samples containing 4.4 ng/g and 4.1 ng/g aflatoxins by LC. Another incorrect response was a false negative on a sample containing 5.5 ng/g aflatoxins by LC. The fourth Incorrect response was a false positive on a sample containing 1.9 ng/g aflatoxins by LC. On the basis of these results, the CITE PROBE was determined to be a reliable screening method for the detection of % 5 ng/g aflatoxins in corn.
Determination of Mirex in Human Blood Serum Containing Poiychiorinated Biphenyis by Using Packed Column Gas Chromatography
Authors: Korver Margaret P , Burse Virlyn W , Needham Larry L , Green Vaughn E , Gray Deborah L , Rouse Mary A , Shelly Tracy L , Mortensen Kim B
Published: February 2020

An analytical method has been developed that uses electron capture/gas-llquld chromatography to determine Mirex In serum containing poiychiorinated biphenyis (PCBs) (Aroclor 1260). With this method, 0.2 ppb Mirex can be determined In 4 mL serum that also contains 10 ppb PCBs. The method provides approximately 70% recovery of Mirex at 1.0 and 3.5 ppb. The coefficients of variation are 4.5 and 4.6% at 1.0 and 3.5 ppb, respectively. In a cooperative study with the Ohio Department of Health, the Centers for Disease Control used this method to determine the extent of exposure of Salem, OH, residents to Mirex. Confirmation of Mirex was obtained by using high resolution gas chromatography and high resolution mass spectrometry.