bluuebunny/crossref_metadata_2025 huggingface dataset:
Atomic Absorption Spectroscopic Determination of Molybdenum in Plant Tissue and Blood Plasma
Authors: Khan Shahamat U , Cloutier Richard O , Hidiroglou Michel
Published: February 2020

A method is presented for determining molybdenum in plant tissue and blood plasma by flame and flameless atomic absorption spectroscopy (AAS). The samples are digested with HNO3- HClO4, and the metal is separated by chelation, extracted into methyl isobutyl ketone, and analyzed by AAS. Recoveries of molybdenum from fortified samples ranged from 92.0 to 98.9%. The limits of detection on the flame and graphite furnace were 10 and 2 ng/mL, respectively.
Minicolumn Detection Methods for Aflatoxin in Yellow Corn: Collaborative Study
Authors: Shannon Gail M , Shotwell Odette L
Published: February 2020

The CPC modified method, the Holaday modified method, and the combination of the 2 procedures have been compared. The CPC modified method involves more cleanup steps but has a more sensitive column. The Holaday modified procedure has fewer cleanup steps, but the column is more difficult to interpret. The combination CPC-Holaday, which has proven to be the most satisfactory, combines the speed and simplicity of the Holaday extraction and the sensitivity of the Velasco minicolumn used in the CPC method. Levels of 10 ng/g were detected by 89% of the collaborating laboratories using the combination, Holaday-Velasco, method. The combination method has been adopted as official first action.
Production of Aflatoxin in Cocoa Beans
Authors: Lenovich Lawrence M , Hurst W Jeffrey
Published: February 2020

Aflatoxin was produced in both non-autoclaved and autoclaved Ivory Coast cocoa beans inoculated with Aspergillus parasiticus NRRL 2999 under optimum laboratory growth conditions. Total aflatoxin levels ranged from 213 to 5597 ng/g substrate. Aflatoxin was quantitated by using high pressure liquid chromatography (HPLC). Raw, non-autoclaved cocoa beans, also inoculated with aspergilli, produced 6359 ng aflatoxin/g substrate. Variation in aflatoxin production between bean varieties was observed. Total aflatoxin levels of 10,446 and 23,076 ng/g substrate were obtained on Ivory Coast beans inoculated with A. parasiticus NRRL 2999 and NRRL 3240, respectively. Aflatoxin production on Trinidad and Malaysian beans was 28 and 65 ng aflatoxin/g substrate. These data support previously reported low level natural aflatoxin contamination in cocoa.
Computerized Gas-Liquid Chromatographic Method for Content Uniformity Analysis of Dicyclomine Hydrochloride Capsules and Tablets
Authors: Brownell Charles R , Alber Larry L
Published: February 2020

An automated, computerized method is presented for the content uniformity determination of dicyclomine hydrochloride capsules and tablets, using up to 4 automatic sampler-equipped gas chromatographs interfaced with a minicomputer. A 3% OV-17 column is used with anthracene as an internal standard. Five sample injections are bracketed by standard mixtures containing about 90 and 110% of the labeled dicyclomine hydrochloride. Data are taken on-line simultaneously from each gas chromatograph and a computergenerated report is produced. Calculations use a BASIC program with linear fit of the 90 and 110% standard mixture. Individual tablet or capsule results are printed in milligrams and per cent declared, including summary calculations of average, high, low, standard deviation, and coefficient of variation. The GLC results are comparable (within 1%) to those obtained using the USP procedure.
Extrusion of Homogeneous Pastes from Small Samples of Dried Fruit
Authors: Neumann Harry J
Published: February 2020

A simple, rapid procedure is described for preparing homogeneous pastes from small quantities of dried fruit or similar soft, pasty material. Raisin pastes prepared from five 60 g samples by extrusion through a plate with 0.046 in. diam holes, and by the AOAC grinding procedure were in close agreement in average moisture content and standard deviation. The amount of sample lost in the equipment was much less by extrusion than by grinding with a food chopper, averaging 1.3 and 32.4 g, respectively. Various dried fruits including apples, apricots, figs, pears, prunes, raisins, and a glacéed fruit mix, with moisture contents of 12.6-33.9%, were extruded as pastes through either 1 plate with 0.046 in. diam holes, or a stack of 3 plates with 0.045, 0.046, and 0.033 in. diam holes, except that figs pressed with 3 plates were compacted. Moisture data from averages of three 25 g samples were equally precise using 3 plates or 1 plate.
Evaluation of 14 Charcoal-Polyurethane Foam Mixtures for the Separation of Mirex and Photomirex from Aroclor 1254
Authors: Babjak Ludwig J , Chau Alfred S Y
Published: February 2020

The efficiency of 14 different types of charcoals mixed with polyurethane foam (40% charcoal/60% foam, w/v) for the separation of photomirex and Mirex from Aroclor 1254 was investigated. Photomirex and Mirex were eluted with 10 mL cyclohexane from minicolumns containing 0.2 g charcoal- foam mixture. An additional elution with 10 mL benzene yielded Aroclor 1254. Average recovery using Norit C-170 charcoal-foam mixture was 99.1% for photomirex at the 1.0 μg level, 100.1% for Mirex at the 1.0 μg level, and 96.8% for Aroclor 1254 at the 3.0 μg level. For the other 13 charcoals investigated, recoveries from duplicate analyses were 47.0-115.5% for photomirex, 71.9-106.1% for Mirex, and 23.3-114.6% for Aroclor 1254.
Comparison of Two Extraction Procedures for Recovering Nitrite from Cured Meat Products
Authors: Sen Nrisinha P , Lee Young C , Mcpherson Marcia
Published: February 2020

A study was undertaken to determine the extent of loss of nitrite during the analytical workup of cured meats for nitrite analysis. Two extraction techniques were compared: (A) a relatively long (2 hr) and hot (80°C) procedure carried out at the natural pH of the sample, and (B) the method of Sen and Donaldson that specifies an alkaline solution and much milder conditions (20 min at 50°C at pH 8) for extraction. The data obtained suggest that considerable losses of nitrite can occur with the former procedure, especially in acidic samples. The overall percentage recoveries of added nitrite by the 2 methods ranged between 20 and 112, and 80 and 114, respectively. Average percentage recoveries for the acidic (pH <5) samples only were 47.2 for Method A as compared with 100.2 for Method B.
Gas Chromatographic-Mass Spectrometric Analysis, Identification, and Detection of Adulteration of Lavender, Lavandin, and Spike Lavender Oils
Authors: Prager Manfred J , Miskiewicz Michael A
Published: February 2020

A gas chromatographic procedure was developed to distinguish lavender, lavandin, and spike lavender oils. Quantitative determination showed that each oil contained about a dozen components present to the extent of 1% or more. These compounds were generally common to the 3 oils. The concentrations of these components fell into characteristic ranges by which the 3 oils could be identified and adulterations could be detected. Samples were identified primarily on the basis of concentrations of limonene, 1,8-cineole, cis-β-ocimene, camphor, linalyl acetate, β-caryophyIlene plus terpineol-4, and borneol.
High Pressure Liquid Chromatographic Determination of the Rodenticide Brodifacoum in Rat Tissue
Authors: Koubek Kenneth G , Ussary James P , Haulsee Ronald E
Published: February 2020

An HPLC method was developed to determine residues of individual isomers of brodifacoum (3-[3-4'-bromo[1,1'-biphenyl]-4-yl)-1, 2, 3, 4-tetrahydro- 1 -naphthalenyl]- 4 -hydroxy-2H- 1 -benzopyran-2-one) in rat tissue. The compound was extracted twice with 10% methanol in chloroform, filtered, and cleaned up by using automated gel permeation chromatography. A final cleanup on a silica gel SEP-PAK was added to protect the analytical column from irreversible adsorption and to reduce analysis time. The analysis was done on a μPorasil column; a UV detector was used for quantitation. Recoveries of brodifacoum added to rat tissue in concentrations of 0.12-5.0 ppm were greater than 90%.
Gas-Liquid Chromatographic Determination of Permethrin in Bovine Tissues
Authors: Oehler Delbert D
Published: February 2020

A method is presented for the determination of permethrin (m-phenoxybenzyl cis,trans-(±)-3-(2,2-dichlorovinyl) - 2,2 - dimethylcyclopropanecarboxylate) in bovine tissues. Fat and muscle samples were cleaned up first by liquid-liquid partition on a bonded phase chromatographic column. Final cleanup of fat and muscle was performed on a short Florisil column. Liver, kidney, spleen, and heart tissues only required cleanup on a Florisil column before quantitation of permethrin by electron capture gas-liquid chromatography.
Quantitative Determination of Tris-(2,3,-dibromopropyl) Phosphate by Densitometry of Thin Layer Chromatograms
Authors: Gardner Albert M
Published: February 2020

The flame retardant tris-(2,3-dibromopropyl) phosphate (Tris) was chromatographed on silica gel thin layer plates, using ethyl acetate-hexane (30+70) as the developing solvent. Tris was visualized by spraying the chromatogram with 1% aqueous silver nitrate followed by exposure to ultraviolet light for 40 min. Tris appeared as dark gray spots on a white background; the spots were quantitated by densitometry at 600 nm. The lower level of sensitivity was 50 ng; calibration plots were linear from 50 to 800 ng. The procedure was developed to determine the levels of unmetabolized Tris remaining after exposure to sewage sludge suspensions. Recovery of Tris from 3 sewage sludge samples fortified at the 1.0 ppm level averaged 97%.
Sampling and Preparation of Samples of Peanut Butter for Aflatoxin Analysis
Authors: Waltking Arthur E
Published: February 2020

Procedures are discussed for sampling peanut butter and preparing those samples for aflatoxin analysis. Special emphasis is placed on sampling the product from shipping pallets and comminuting chunk style peanut butter in order to reduce the variability in the analysis associated with the nonuniform distribution of aflatoxin in the product. The slurry method of preparation is a convenient means of obtaining a sample which is representative of a nonhomogeneous product.
Confirmatory Test for the High Pressure Liquid Chromatographic Determination of Aflatoxin B1
Authors: Davis Norman D , Diener Urban L
Published: February 2020

The iodine derivative of aflatoxin B1 was determined by reverse phase high pressure liquid chromatography with fluorescence detection. Aqueous solutions of aflatoxin B1 were chromatographed on a Bondapak C18 column with methanol–water before and after treatment with iodine. A 4.5-min shift in retention time and a 25-fold increase in fluorescence resulted from the reaction.
Gas-Liquid Chromatographic Determination of Chlorinated Benzenes and Phenols in Selected Biological Matrices
Authors: Lamparski Lester L , Langhorst Marsha L , Nestrick Terry J , Cutié Sergio
Published: February 2020

The determination of higher chlorinated benzenes and chlorinated phenols at parts per billion or parts per million levels in biological samples is described. The method includes sulfuric acid digestion, silica gel column chromatography, methylation, alumina column chromatography, and detection by electron capture gas chromatography. Recoveries are reported (or fish flesh, rabbit tissues, and duck tissues with detection limits of 10-15 ppb (ng/g tissue).
Argon Plasma Emission Spectrometry of Boron in Fertilizers: Comparison with Spectrometric and Distillation Procedures
Authors: Woodis Terry C , Hunter G Bradley , Holmes John H , Johnson Frank J
Published: February 2020

A much faster and equally accurate method is described for determining boron in fertilizers by argon plasma emission spectrometry at 249.67nm. Results by the method are compared with results from a methyl borate distillation method and a modified azo-methine H spectrometric procedure. No significant differences in results were found among the methods studied.
High Pressure Liquid Chromatographic Determination of Antihistamine-Adrenergic Combination Products
Authors: Bachman William J
Published: February 2020

Reverse phase high pressure liquid chromatography (HPLC) with ion-pairing is used for the determination of pseudoephedrine hydrochloride in combination with triprolidine hydrochloride or chlorpheniramine maleate in sirups and tablets. Sirups require a preliminary column chromatography cleanup step. Response is linear for pseudoephedrine hydrochloride (range of 0–20 μg), chlorpheniramine maleate (range of 0–1.3 μg), and triprolidine hydrochloride (range of 0–1.0 μg). Recoveries from synthetic formulations were 98.8–101.3% for pseudoephedrine hydrochloride, 100.0–101.2% for chlorpheniramine maleate, and 97.7–99.8% for triprolidine hydrochloride. The coefficient of variation for the method is less than 1%.
Protocols for Surveys, Sampling, Post-Collection Handling, and Analysis of Grain Samples Involved in Mycotoxin Problems
Authors: Davis Norman D , Dickens J William , Freie Robert L , Hamilton Pat B , Shotwell Odette L , Wyllie Thomas D , Fulkerson J F
Published: February 2020

This report examines and summarizes current knowledge regarding mycotoxin surveys, sampling techniques, conditions conducive to post-collection production of mycotoxins in grain samples, and analytical methods for mycotoxin analysis. Priority attention is given to samples of corn suspected of containing aflatoxin. The report includes recommendations where deemed appropriate by the Ad Hoc Work Group
Spectrophotometric Determination of Carbofuran Residues in Water
Authors: Handa Swadesh K
Published: February 2020

A spectrophotometric method has been developed for the microdetermination of carbofuran in water. The method is based on the reaction of carbofuran phenol (2,3-dihydro-2,2-dimethyI-7-hydroxy benzofuran) with nitric acid to form a colored compound with an absorption maximum at 345 nm. The method is applicable to residues in the range 10-150 μg/5 mL solution.
Gas-Liquid Chromatographic Determination of Melengestrol Acetate in Cattle Feed Supplements: Collaborative Study
Authors: Davis Raymond A , Kratzer D Dal , Geng Shu ,   Collaborators:, Barney S L , Jeffus M T , Karnemaat J N , Pollack R , Sics U , Zietlow D C
Published: February 2020

The assay for melengestrol acetate (MGA) in cattle feed supplements was the subject of a collaborative study using 6 laboratories. Two feed formulations were each fortified with 0, 0.0625, 0.125, 0.500, 1.00, and 1.50 mg MGA/lb of supplement, and each laboratory assayed 4 samples of each level of each formulation by electron capture gas chromatography after liquid-liquid extraction of each sample followed by solvent partition and column chromatography cleanup procedures. Overall recovery was 83.2% with a pooled within-laboratory sample-to-sample standard deviation of 9.5%. This includes the variability due to formulation, batches, days, levels of MGA, samples, and their interactions. Including the collaborators as a source of variance results in an overall standard deviation of 15.0%. The major sources of variability were associated with collaborator, formulation, and level of MGA. Lower than expected recoveries were attributed to difficulty in recovering MGA from samples containing concentrations of MGA below the range of the method and the inadvertent substitution by some laboratories of ethanol-free chloroform for the ethanol-containing reagent grade chloroform specified in the methodology. On the basis of the collaborative results, the method has been adopted as official first action for MGA in cattle feed supplements at concentrations from 0.125 to 1.00 mg MGA/lb.
High Performance Liquid Chromatographic Determination of Fructose, Glucose, and Sucrose in Molasses
Authors: Damon Carolyn E , Pettitt Bruce C
Published: February 2020

Fructose, glucose, and sucrose were determined quantitatively in molasses by high performance liquid chromatography (HPLC) using maltose as an internal standard. After a simple cleanup procedure, chromatographic separation required less than 20 min for the 17 molasses samples. HPLC gave lower results for reducing sugars (fructose plus glucose) and for sucrose by an average of 3.9 and 1.2%, respectively, when compared to results obtained by classical methods. The lower values are believed to result from elimination of interfering substances by this method. The values probably reflect more accurately the true composition of the molasses. Repetitive injections of a standard solution indicated a coefficient of variation of 2.0% for fructose and glucose and of 2.2% for sucrose.
Solvent Extraction and Flameless Atomic Absorption Determination of Arsenic in Biological Materials
Authors: Thiex Nancy
Published: February 2020

This method for the determination of arsenic specifies wet digestion of biological materials, followed by reduction of arsenic(V) to arsenic(III) and extraction of arsenic(III) with diethylammonium diethyldithiocarbamate (DDDC) in chloroform. The extract is analyzed by flameless atomic absorption spectrometry (AAS). Recoveries of arsenic from plant and animal tissues ranged from 88 to 108%, averaging 99%. Analyses of rat tissues, using a radioisotope technique, averaged 103% of theoretical. Repeatability studies on rat tissues showed the method to be consistent with coefficients of variation ranging from 3.0 to 8.5%, and a test for ruggedness showed that the method is not affected by slight variations in procedure, but is affected by the presence of Fe and Cu. The method is sensitive to about 0.04 μg arsenic in the total digest (injections of 20 μl of a 4 ng/mL solution).
Preliminary Comparison of Methods for Determining Sodium in Fertilizers
Authors: Corominas Luis F , Boy Victor M , Guijosa Manuel
Published: February 2020

The AOAC official first action method 2.147–2.150 for the flame emission spectrophotometric (FES) determination of sodium in fertilizers was compared with the atomic absorption spectrophotometric (AAS) method and the sodium selective electrode (SSE) method. Two synthetic NPK samples, 3 commercial samples (urea, DAP, and superphosphate), 2 Magruder NPK check samples, and one Magruder muriate check sample were used for the study. Statistically significant differences were obtained in both averages and standard deviations for all samples. In general, the precision for all methods was acceptable; the AAS method seems to be the more accurate; the AOAC method needs to be revised; and the SSE method has the tendency to give higher values. Additional experimental work is necessary to define which method is the most convenient.
Enumeration and Confirmation of Bacillus cereus in Foods: Collaborative Study
Authors: Lancette Gayle A , Harmon Stanley M ,   Collaborators:, Brooks D , Bryant R , Chiu J , Graham J , Guilfoyle D , Hill W , Latt T , Noah C , Placencia A , Pratt M , Radle D , Smith A , Solomon H , Staben D , Stern N , Thaker N
Published: February 2020

A collaborative study was conducted in 15 laboratories to evaluate 2 different techniques for enumerating Bacillus cereus in foods. A direct plating technique using mannitol-egg yolk-polymyxin agar and a most probable number (MPN) technique using trypticase-soy-polymyxin broth were compared for the enumeration of high and low populations of B. cereus in mashed potatoes. The collaborative results showed that the overall mean recovery obtained with the low population level was essentially the same by both techniques. However, the overall mean recovery was significantly higher by the direct plating technique at the high population level. A statistical evaluation of the data also showed that the direct plating technique had better repeatability and reproducibility than did the MFN technique at both the high and low population levels. These results suggest that the MPN technique is suitable for examining foods containing low populations of B. cereus, but that the direct plating technique is preferable for foods that contain a high population of this organism. The confirmatory technique used in the proposed method is reliable for presumptive identification of isolates as B. cereus. The method has been adopted as official first action.
Freezing Point Measurement of Lactose Hydrolysis in Acid Whey and Lactose Solutions
Authors: Baer Robert J , Frank Joseph F , Loewenstein Morrison
Published: February 2020

A method for determining lactose hydrolysis by freezing point determinations is described. There is a direct relationship between freezing point and lactose hydrolysis in neutralized acid whey (r = 0.985) and lactose solutions (r = 0.998). In both the acid whey and the lactose solutions that contained 4.6 to 5.0% lactose, the freezing point was depressed approximately 0.050°H for each 1% lactose hydrolyzed
High Performance Liquid Chromatographic Determination of Carbohydrates in Chocolate: Collaborative Study
Authors: Hurst W Jeffrey , Martin Robert A ,   Collaborators:, Bueno M , Clemente H , DeVries J W , Levi C , Li B , Popovich D J , Sheeley R , Schumacher D , Stewart K , Taylor J , Toomey P
Published: February 2020

A collaborative study determining sucrose, glucose, fructose, maltose, and lactose in chocolate products was conducted using a previously published high performance liquid chromatographic (HPLC) method. Five samples (2 milk chocolates, 1 dark chocolate, 1 powdered mix, and 1 sirup) were analyzed in duplicate by 7 collaborators. The results indicate adequate method precision. In addition, the HPLC method allows for the simultaneous determination of 5 saccharides in chocolate products in 15 min. The method has been adopted as official first action.
Extraction and Cleanup of Soil Arsenical Residues for Analysis by High Pressure Liquid Chromatographic–Graphite Furnace Atomic Absorption
Authors: Iadevaia Rosa , Aharonson Nadav , Woolson Edwin A
Published: February 2020

An analytical procedure for the extraction and cleanup of arsenical residues from soil was developed to meet the specific requirements for separation by high pressure liquid chromatography (HPLC) and on-line analysis by a graphite furnace atomic absorption spectrophotometer (GFAA). Soil samples were extracted with 2M aqueous NH4OH, cleaned on a carbon-Celite chromatographic column, concentrated to 1 g soil extract equivalent per mL, and determined by HPLC-GFAA. Recovery values were as follows: dimethylarsinic acid (cacodylic acid, CA) 90%; methanearsonic acid (MAA) 83%; arsenate 56%; and arsenite 64%. The limit of detection was 0.5 ppm in soil. Additional cleanup on cellulose thin layer chromatographic (TLC) plates improved sensitivity to less than 0.1 ppm and also served for confirmation of identity. The soil extract matrix did not appear to affect GFAA signal response. High salt content in concentrated soil samples altered the dimethylarsinic acid HPLC retention volume. By the time of analysis, arsenite was completely oxidized to arsenate in soil extractant.
Carbon–Foam Chromatographic Separation of Non-o,o´-Chlorine Substituted PCBs from Aroclor Mixtures
Authors: Huckins James N , Stalling David L , Petty Jimmie D
Published: February 2020

Columns of activated carbon dispersed on shredded polyurethane foam were used to separate non-o,o´-chlorine (Cl) substituted polychlorinated biphenyls (PCBs) from mg quantities of Aroclors 1016, 1242, 1248, 1254, and 1260. Aroclor 1248 contained the highest concentration (3400 μg/g) of highly toxic 3,4,3´,4´tetrachlorobiphenyl (TCB). Lesser amounts of 3,4,3’,4’-TCB were also found in Aroclors 1242 and 1254. However, we were unable to detect 3,4,3’,4’-TCB in Aroclors 1016 and 1260. Varying amounts of the non-o,o´-Cl substituted 3,4,4´-trichlorobiphenyl and 3,4,3´,4´,5´-pentachlorobiphenyl were found in most of the Aroclor mixtures. No residues of 3,4,5,3´,4´,5´-hexachlorobiphenyl were detected in the Aroclor mixtures examined. Using carbon-foam chromatography and high resolution capillary gas chromatography, 0.11 μg 3,4,3´,4´-TCB/g was detected in 3 subsamples of a composite of 5 carp from the Ohio River.
Standardizing Soil Testing Methods
Authors: Sabbe Wayne
Published: February 2020

Soil tests are performed to determine the amount of nutrients available to plants so that fertilizer and lime recommendations can be formulated. In 1951, State soil testing laboratories had numerous extractants for determining phosphorus and potassium. Twenty years later, only 3 extractants each were used for phosphorus and potassium. In the United States, a regional approach produced standardized methods for several of the most common soil testing procedures. These detailed standard methods resulted from identifying procedural causes for variations in soil test results. For example, the amount of nutrient extracted varied by size and shape of extraction vessel and speed and time of shaking. Currently, terminology and expression of soil test results, and a search for a more universal soil extractant, i.e., one that can be used to determine several rather than a single nutrient, are 2 of the main areas of effort.
Multielement Emission Spectroscopic Analysis of Plant Tissue Using DC Argon Plasma Source
Authors: Debolt Darrell C
Published: February 2020

A method for elemental analysis of plant tissue, using the Spectraspan III with a dc argon plasma emission source, is presented. Values are reported for boron, phosphorus, zinc, manganese, magnesium, molybdenum, aluminum, iron, copper, calcium, and potassium. NBS Orchard Leaves and NBS Tomato Leaves Standard Reference Material and a soybean tissue sample from 7 separate sample preparations and ashings are analyzed. Instrument operation is relatively simple, with rapid startup. Analysis is fast, requiring only 1.25 min/sample. Results and standard eviations compare favorably with NBS certified values for most elements. Dry ashing is responsible for differing results in the analyses for iron and aluminum. The discrepancy for molybdenum cannot be explained at present.
Acid Digestion, Hydride Evolution Atomic Absorption Spectrophotometric Method for Determining Arsenic and Selenium in Foods: Part II. Assessment of Collaborative Study
Authors: Ihnat Milan , Thompson Brian K
Published: February 2020

Results obtained from the recent collaborative study of a hydride evolution atomic absorption spectrophotometric method for determining arsenic and selenium in foods have been studied intensively. Various parameters relating to the method have been considered: accuracy (excellent agreement between reference data and means over all laboratories for both model solutions and food samples; considerable bias for individual laboratories); precision within laboratory (repeatability coefficients of variation of 0.07–0.15) and among laboratories (reproducibility coefficients of variation of 0.13–0.28); frequency of outlying data from model solutions and biological samples (rejection rate from 9 to 29%); and detection limits (estimated as 80 and 120 ng/g for As and Se, respectively). Attempts were made to interrelate these parameters and to relate them to hydride generator characteristics and to other aspects of the procedure, namely, hydride generator type; absorba nee-time peak width; standard curve slope, linearity, and precision; sample type; reagent blank magnitude; collaborator experience with sample treatment and hydride generation procedures, and departures from prescribed sample treatment procedure. On the basis of information from 28 laboratories using 16 different types of hydride generation apparatus, conducting 700 complete analyses and 2400 analyte quantitations on reagent blanks, 3 model solutions, and 13 different reference food samples with levels of As and Se ranging from 0 to 15,000 and 0 to 4,000 ng/g, respectively, the authors conclude that the method suffers from both systematic error and imprecision, and hence recommend that the method not be adopted.
Comparison of Methods for Determination of Sulfur in Fertilizer: Collaborative Study
Authors: Thorpe Virginia A ,   Collaborators:, Bailey L , Erickson E , Fathergill L , Gehrke C , Holmes J H , Jones N , Lonn P , McAvoy R L , Moore E J , Price R N , Sensmeier R K , Silkey J R , Sweeney R A , Winters J M , Woodis T C
Published: February 2020

Methods with applications for total sulfur (sulfate, elemental sulfur) in dry fertilizers, for total sulfur (sulfate, sulfite, thiosulfate, sulfide) in liquid fertilizers, for total sulfur (elemental sulfur) in sulfur-coated urea and elemental sulfur formulations, and for thiosulfate sulfur in ammonium thiosulfate liquid fertilizer (12-0-0, 26 S), and 7 samples with background and directions were submitted to 12 collaborating laboratories for comparison to official methods 2.160–2.161 and 2.162. The methods studied are simple and rapid, and recover the total sulfur in fertilizers containing high levels of elemental sulfur and thiosulfate sulfur. Method 2.160–2.161 does not recover total sulfur in these products. The first 3 methods have been adopted as official first action, and the present official methods for sulfur, 2.160–2.161 and 2.162, have been repealed, official first action.
Isomer Specific Assay of Ester and Salt Formulations of 2-Methyl-4-chlorophenoxyacetic Acid and 2,4,5-Trichlorophenoxyacetic Acid by High Pressure Liquid Chromatography: Collaborative Study
Authors: Grorud Robert B , Stevens Timothy S ,   Collaborators:, Barry C , Fisher J R , Grimes G S , Hageman L , Hodgins E , Jones C , Klimstra W , Law M W , MacEachern G , Meyer D R , Plunkett R W , Rivera L , Stevens T S , Wong D L
Published: February 2020

HPLC methodology for ester and salt formulations of 2 methyl-4-chlorophenoxyacetic acid (MCPA) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-TA) has been substantiated in 2 collaborative studies. The methods closely follow the AOAC method for 2,4-dichorophenoxyacetic acid (2,4-DA), including preparation of samples by addition of a saponification internal standard solution to all samples. A microparticulate column in the reverse phase ion suppression mode separates all known impurities from the internal standard and MCPA, or 2,4,5-TA. The only differences in essential parameters between the 2 methods concern the internal standard, strength of solvent (acetonitrile), and pH of the acidic buffered eluant. One of the test samples is a combination of 2,4,5-TA and 2,4-DA as an ester formulation and each herbicide is quantitated on the same chromatogram. In respective acid equivalent, the coefficient of variation ranged from 1.67% for the 45% 2,4,5-TA ester formulation to 2.36% for the 22% 2,4,5-TA component in the combination ester formulation of 2,4-DA and 2,4,5-TA. There were 14 collaborators from the United States and Canada including 6 from industry and 8 from government agencies. The methods have been adopted as official first action.
Revised Method for Aflatoxins in Cottonseed Products, and Comparison of Thin Layer and High Performance Liquid Chromatography Determinative Steps: Collaborative Study
Authors: Pons Walter A , Lee Louise S , Stoloff Leonard ,   Collaborators:, Athnasios A K , Beebe R H , Francis O , Franz A O , Routh J H , Scott P M , Smiechowski R , Stubblefield R D , Theane J , Thorpe C , Trucksess M , Waltking A E
Published: February 2020

Modifications to save analyst time and reagents have been made in the rapid method for separation and quantitation of aflatoxins in cottonseed products. A collaborative study of the revised method, including optional high performance liquid chromatography (HPLC) in addition to thin layer chromatography for the determinative step, showed no change in the method precision or accuracy due to the modifications and no significant difference in the values obtained by either determinative procedure. The HPLC technique provided no significant difference in analysis repeatability, but did reduce the betweenlaboratory error component. The method has been adopted as official first action.
Determination and Confirmation of Identity of Aflatoxin M1 in Dairy Products: Collaborative Study
Authors: Stubblefield Robert D , Van Egmond Hans P , Paulsch Walter E , Schuller Pieter L ,   Collaborators:, Brawn P R , Everitt J , Franz A , Gamilinda I A , Jangula E , Jans J A , Jemmali M , Juskiewicz T , Kato T , Lee L , Kronert W , Meyer H , Ozaki M , Patterson D S P , Polzhofer K P , Shannon G M , Sizoo E A , Srebrnik S , Stemp A , Trucksess M , Tuinstra L G M T , Rensburg S J van , Veldhuizen C J van , Vick T , Webb M , Weissd G , Whitcomb D
Published: February 2020

An international collaborative study involving 23 collaborators was conducted to test methods, improved over previous methods with respect to speed and solvent use, for the rapid determination and thin layer chromatographic (TLC) confirmation of aflatoxin M1 identity in dairy products. For the quantitative method, collaborators assayed samples of Couda and cheddar cheeses, powdered milk, and butter containing levels of M1 near the anticipated limit of determination. Statistical analysis of the study results indicated that the lower limit of determination and precision of this method were comparable to these parameters of methods previously approved for analysis for aflatoxin M1. A few collaborators found that M1 eluted early from cleanup columns with cheese and butter samples and that emulsions formed during powdered milk sample extraction. The reasons for these problems have been determined and remedies are provided. For the TLC confirmation of identity method, collaborators prepared trifluoroacetic acid derivatives of M1 on the plates after 2-dimensional development. Concentrations as low as 0.3 ng/g cheese and 1.0 ng/g powdered milk were determined in this study. As a result of this study, both methods have been adopted as official first action methods by the AOAC and as reference methods by IUPAC.
Improved Monomolecular Fat Film Method for Determination of Yolk in Egg Albumen
Authors: Taber Lawrence E
Published: February 2020

The monomolecular film method can be simplified by an improved quantitation procedure. Following the extraction of the fat from the albumen and subsequent evaporation, the redissolved sample is applied to a round glass plate containing 1 in. pH 5 acetic acid solution topped by a film of oxidized oil sufficient to exhibit a color of third order green. The sample aliquot is dropped from a 100 μL Hamilton syringe directly at the center of the oil surface. A circular pattern results. The diameter of the pattern is measured in centimeters with a ruler placed under the glass plate. The area of the pattern is then calculated by the formula for the area of a circle.
Multiresidue Method for Determining N-Methylcarbamate Insecticides in Crops, Using High Performance Liquid Chromatography
Authors: Krause Richard T
Published: February 2020

A method is described for determining 7 carbamate insecticide residues (aldicarb, bufencarb, carbaryl, carbofuran, methiocarb, methomyl, and oxamyl) and 4 related carbamate metabolites (aldicarb sulfone, aldicarb sulfoxide, 3-hydroxy carbofuran, and methiocarb sulfoxide) on fruits, vegetables, and grains. Residues are extracted from the crops using methanol, and plant coextractives are removed using solvent partitioning and a charcoal-silanized Celite column. The carbamate residues are then separated on a reverse phase high performance liquid chromatographic (HPLC) column using an acetonitrile-water gradient mobile phase. The eluted residues are detected using an in-line post-column fluorometric detection technique. Recovery data were obtained by fortifying 9 crops (apples, carrots, green beans, green peppers, lettuce, oranges, soybeans, strawberries, and tomatoes) with the 7 carbamates and 4 carbamate metabolites. Except for aldicarb sulfoxide, pesticide recovery averaged 99% at both the 0.05 and 1.0 ppm fortification levels, with standard deviations of 5.0% (n = 86) and 5.6% (n = 87), respectively. The average recovery for aldicarb sulfoxide, a very polar carbamate metabolite, was 55 and 57% at the 0.05 and 1.0 ppm levels, respectively. An intralaboratory study of the method was conducted. Recovery data were obtained by fortifying grapes and potatoes with carbaryl, carbofuran, 3-hydroxy carbofuran, methiocarb, and methomyl at levels ranging from 0.05 to 15 ppm. Determinations were made in duplicate and the average recovery was 95% (range 87–101%).
Improved Microbiological Procedure for Determining Erythromycin in Milk and Some Milk Products
Authors: Harpster Carol P , Katz Stanley E
Published: February 2020

An improved microbiological assay for erythromycin in milk and some milk products was developed. Acidification of the samples to pH 4.5 resulted in precipitation of milk solids which were separated by centrifugation. The pH of the aqueous supernatant solution was readjusted to pH 8.0 to obtain maximum sensitivity. The sample cleanup and the use of a single, thin, seeded agar layer with Micrococcus lutea as the assay organism permitted the measurement of 0.05 μg/mL milk with recoveries averaging 84.0%, 0.50 μg/g nonfat dry milk with recoveries averaging 55.4%, 0.10 μg/g cream cheese with recoveries averaging 100.2%, and 0.05 μg/mL buttermilk with recoveries averaging 44.0%. The improved procedures showed superior recoveries and improved the ability to detect and measure lower levels when compared with commonly recommended assay procedures for erythromycin residues.
Determination of Extractable Mirex in Whole Blood
Authors: Stahr H Michael , Hyde Walter , Gaul Michael
Published: February 2020

A method for the determination of free mirex in blood has been developed in which whole blood is extracted with acetone–hexane (9+91), passed through Na2SO4, concentrated, and analyzed by electron capture gas-liquid chromatography (GLC). Results were highest for fresh blood. Recoveries were verified by determining 14C-labeled mirex before and after extraction. Little mirex was detected in the samples after extraction. Hydrolysis of residual blood indicates that a metabolite of mirex is released. The possible metabolite has a CLC retention time and mass spectrum which resemble hydroxy metabolites of mirex.
Evaluation of Milkoscan 104 Infrared Milk Analyzer
Authors: Voort F R Van De
Published: February 2020

The Milkoscan 104, a single cell, dual wavelength infrared milk analyzer, was assessed to see if it would meet the newly set AOAC specifications for accuracy and reproducibility required for official sanctioning of the instrument for milk component analysis. This assessment was carried out using herd, individual cow, commercial, and composite random milks, and produced mean differences and standard deviations of difference of <0.02% and ±0.02% for reproducibility and <0.05% and ±0.06% for accuracy. Results outside these values were encountered in the individual cow milks, for which the instrument was not specifically calibrated. The average molecular weight of the milkfat was an important variable because 2 anomalous milks were present in the calibration milks, thus restricting the overall accuracy obtainable. Linear regression analysis of chemical vs instrumental results showed good linearity and provided standard errors of the estimate of the same magnitude as the standard deviation of the differences. A separate assessment of the instrument for within- and between-day variation showed no practical significant differences. Based on the overall results, the Milkoscan 104 was judged to be capable of meeting the AOAC specifications set for fat, protein, and lactose analysis.
Spectrophotometric Determination of Rozol in Paraffinized Formulations
Authors: Kawano Yoshihiko , Chang Wanda
Published: February 2020

Rozol (2-[(ρ-chlorophenyl)phenylacetyl]-l,3-indandione) in paraffinized baits is extracted with benzene. The extract is placed on a Florisil column. Paraffin and other interfering substances are removed by washing with benzene, carbon disulfide, and hexane. Rozol is eluted with acidic ethanol. The eluate is analyzed with an ultraviolet spectrophotometer by scanning between 360 and 240 nm and measuring the absorbances at 350 and 321 nm. The amount of Rozol is calculated by comparison with a standard, and a correction is made from the recovery of a fortified sample. Recoveries from fortified samples averaged 93.7%. The linearity of measurement of Rozol at 321 nm ranges from 2 to 10 μg.
Gas-Liquid Chromatographic Method for the Analysis of Microencapsulated Ethyl Parathion and Methyl Parathion Insecticides: Collaborative Study
Authors: Karr James J ,   Collaborators:, Antles H D , Audino J B , Bontoyan W R , Carlstrom A A , Conner D , DiPilla E J , Ellis N D , Gentry G M , Gilmore P K , Hayes E , Helfant L J , Jensen D J , MacEachern G M , Bontoyan W R , Minyard J P , Topping A , Ullrich L , VandeLinde D C , Wargacki R E , Whitaker R
Published: February 2020

The determination of ethyl parathion in Penncap-E insecticide was studied collaboratively by 14 laboratories. The assay of methyl parathion in Penncap-M insecticide was studied by 8 laboratories. The original method which was adopted official first action for methyl parathion specified dimethoate, which is currently classified as a suspected carcinogen, as the internal standard. The current collaborative efforts were conducted as a supplemental study to evaluate the performance of the new internal standard, bis-2-methoxyethyl phthalate, and to test the gas-liquid chromatographic method for microencapsulated ethyl parathion (internal standard, dibutyl phthalate). The method uses essentially the same grinding and extraction with acetonitrile as the original study. At the 20% methyl parathion level, the standard deviation within laboratories was 0.186%, and among laboratories, 0.737%. Two formulations of ethyl parathion at approximately 16 and 24% were analyzed in replicate on 2 days by the same analyst, and provided excellent agreement within laboratories as well as among laboratories. The standard deviation (pooled) within laboratories was 0.284% and among laboratories, 0.518%. The method has been adopted as official first action.
Paired-Ion Chromatography and High Performance Liquid Chromatography of Labetalol in Feeds
Authors: Townley Edward R , Ross Bruce
Published: February 2020

A high performance liquid chromatographic (HPLC) method using reverse phase paired-ion chromatography and ultraviolet detection at 280 nm has been developed to determine labetalol, an alpha and beta adrenoceptor blocking agent, in Purina No. 5001 rodent chow. The method is simple and rapid, and demonstrates a separation technique applicable to other acidic and basic drugs. It requires only extraction of the drug with methanol–water–acetic acid (66+33+1) and separation of insoluble material by filtration before HPLC. Labetalol, is chromatographically separated from soluble feed components by means of a µBondapak C18 column and methanol–water–acetic acid (66+33+1) mobile phase, 0.005M with respect to sodium dioctylsulfosuccinate pairedion reagent. Average recovery is 98.7% with a relative standard deviation of ±2.3% for the equipment described.
High Pressure Liquid Chromatographic Determination of 5-(Hydroxymethyl)-2-Furaldehyde in Caramel Solution
Authors: Alfonso Felipe C , Martin Glenn E , Dyer Randolph H
Published: February 2020

An HPLC method is described for the detection of caramel color by measuring the level of 5-(hydroxymethyl)-2-furaldehyde (5-HMF). For the several products of caramelization examined, 5-HMF was the most sensitive indicator of the presence of caramel. The method specifies a reverse phase C18 column, a UV detector set at 277 nm, and a methanol-water gradient to separate 5-HMF from interfering substances. Other flavor compounds resolved by the same gradient are vanillin, ethyl vanillin, coumarin, benzaldehyde, caffeine, anethole, theobromine, and cinnamaldehyde.
Colorimetric Determination of Capsaicin in Capsicum Fruits
Authors: Bajaj Krishan L
Published: February 2020

A simple and accurate colorimetric method has been developed for quantitative determination of capsaicin in capsicum fruits. The method does not involve prior isolation of capsaicin from green capsicum fruits, and interference due to pigments is accounted for by determining a blank. Interfering substances are removed from red capsicum fruits by column chromatography using basic alumina as adsorbent. Capsaicin from the ethyl acetate extract of dried fruits is determined by developing a yellow complex with sodium nitrite–sodium molybdate reagent, which is read at 430 nm. Lambert-Beer’s law is obeyed in the concentration range 1.5–33.5 μg capsaicin/mL. The method is reproducible and is applicable to the rapid determination of capsaicin content.
Quality Assurance in the Analysis of Foods for Trace Constituents
Authors: Horwitz William , Kamps La Verne R , Boyer Kenneth W
Published: February 2020

An examination of the results of over 50 interlaboratory collaborative studies conducted by the AOAC on various commodities for numerous analytes shows a relationship between the mean coefficient of variation (CV), expressed as powers of 2, with the mean concentration measured, expressed as powers of 10, independent of the determinative method. Some typical CV values are: drug formulations at a 1% concentration, 2%; sulfonamides in feeds at a 0.01% concentration, 4%; pesticide residues and toxic elements, 10 6 (1 ppm), 16%; and aflatoxins 10 8 (10 ppb), 32%. Analytical work at trace levels must be constantly monitored through analysis of reference materials and surrogate samples, and by independent replication.
Ion-Pair High Performance Liquid Chromatography of Synthetic Water-Soluble Acid Dyes
Authors: Puttemans Marc L , Dryon Louis , Massart Désiré L
Published: February 2020

The ion-pair chromatography of food dyes is studied in 2 reverse phase HPLC systems. Tetrabutylammonium is used as counter ion in the mobile phase. In the first system, a C18 stationary phase and water-methanol eluants, the influence of methanol content and counter ion concentration was investigated. The second system, 1-pentanol coated on hydrophobic support as the stationary phase, gave higher retention times than did the first system with similar counter ion concentrations. The two systems complement each other and permit the complete separation of all dyes investigated.
New Brine Saturation Method for Extraction of Light Filth from Corn Meal: Collaborative Study
Authors: Freeman Clarence C ,   Collaborators:, Nagy J , Schafer P , Senff W A , Stricklin M , Trauba D , Velzen W Van , Washbon E , Whiteman A
Published: February 2020

An improved method has been developed for extracting light filth from corn meal. The proposed method uses only tap water, salt, olive oil, and alcohol, eliminating the need for costly and toxic solvents for the separation. Reports from 8 collaborators showed that recovery was 95.8% for insect fragments and 84.3% for rodent hairs by the proposed method, as compared with 90.6 and 88.6%, respectively, by the official method. The proposed method has been adopted as official first action to replace official method 44.042 for corn meal only.
pH Determination in Acidified Foods: Collaborative Study
Authors: Boland Frederick E , Lin Rong C , Mulvaney Thomas R , Mcclure Foster D , Johnston Melvin R ,   Collaborators:, Adkins D , Cox B , Durany G , Gould W A , Halaby G , Hill M , Hoffman C , Huhtanen C , Ito K , Klein P , Krout D , O’Korn F , Thorn J V , Yetts S
Published: February 2020

A proposed method for determining pH of acidified foods has been developed and subjected to collaborative study. The method appears to be both accurate and precise. Five samples consisting of pimientos, marinated pimientos, 2 pH buffer solutions, and chocolate syrup were sent to each of 12 collaborators along with a copy of the method. Two of the collaborators were FDA District laboratories while the remainder were representatives from industry, universities, and state health agencies. Many different types of pH meters and combinations of electrodes were used by the collaborators. The tabulated results from the collaborators are presented. The method has been adopted official first action.