bluuebunny/crossref_metadata_2025 huggingface dataset:
General Method for Determination of Pesticide Residues in Samples of Plant Origin, Soil, and Water. I. Extraction and Cleanup
Authors: Ambrus Árpád , Lantos János , Visi Éva , Csatlós Imre , Sárvári Lászlo
Published: February 2020

Acetone extraction followed by partition into methylene chloride is used to extract organophosphate, organochlorine, carbamate, thiocarbamate, urea, triazine, and other types of pesticides. The efficiency of acetone extraction is demonstrated with different samples and compounds. A general extraction scheme is presented which is suitable for the determination of parent compounds and many of their metabolites. Different samples are divided into 8 groups according to the extraction process and cleanup on mixed adsorbent (active carbon, magnesia, diatomaceous earth), alumina, or silica gel columns. Maximum possible loads, depending on sample type and mode of detection, are given for each adsorbent. The method is suitable for 143 of the 257 pesticides used in Hungary.
Automatic Incubator for Use with Modified A-l Test for Enumerating Fecal Coliform Bacteria in Shellfish Growing Waters
Authors: Cook David W
Published: February 2020

An automatic water bath incubator which can be constructed from easily obtainable materials is described. This incubator provides temperatures necessary for both the 35 ± 0.5°C resuscitation period and the 44.5 ± 0.2°C final incubation period as required in the AOAC method for enumerating fecal coliforms by the modified A-l test. Statistical analysis of experimental data indicated no significant differences (P> 0.50) in fecal coliform counts obtained by using the automatic incubator and the AOAC incubation method.
Microdiffusion and Fluoride-Specific Electrode Determination of Fluoride in Infant Foods: Collaborative Study
Authors: Dabeka Robert W , Mckenzie Arthur D ,   Collaborators:, Baetz R A , Bingham D W , Bohm G , Brown L C , Cavlovic P , Fee S A , Goul J , Hall R J , Hancha J -P , Helle L , Jacobso J S , Johnson R D , Keashly R , Mankotia M , Mietz J L , Nixon G , Peters T , Shreve M , Smith B F
Published: February 2020

Twelve laboratories analyzed (1 replicate) 12 samples of infant foods – milk, pears, and peas – containing 0.2-5 ppm F. There was one laboratory outlier. Mean coefficients of variation were 7.06% for intralaboratory determination of 3 sets of blind duplicates and 21.6% for interlaboratory determination of 12 samples. Variance analysis for all samples yielded a reproducibility standard deviation of 0.41 ppm; for 3 sets of blind duplicates, repeatability standard deviation was 0.26 ppm and reproducibility standard deviation was 0.32 ppm.
High Pressure Liquid Chromatographic-Thermal Energy Determination of N-Nitrosodiethanolamine in Cosmetics
Authors: Ho Julia L , Wisneski Harris H , Yates Ronald L
Published: February 2020

Methods for the determination and confirmation of N-nitrosodiethanolamine (NDELA) in cosmetic products were developed. The NDELA fraction was isolated from a cosmetic product by a series of solvent extractions which were designed to concentrate the NDELA and remove ingredients deleterious to the analytical system. The isolated fraction was then analyzed for NDELA using a high pressure liquid chromatograph (HPLC) interfaced with a thermal energy analyzer (TEA). The compound was measured by comparison of detector response with those of known standards. NDELA was verified by gas chromatography-mass spectrometry of the silyl derivative after preliminary cleanup of the sample by gradient elution HPLC on a Partisil 10 PAC column. The limit of detection of NDELA by TEA is 2-3 ng, which corresponds to 20-30 ppb in the cosmetic product. Analysis of an emulsion cream and a hair grooming gel spiked at 3 and 4 ng concentration levels, respectively, yielded recoveries ranging from 71 to 103% (average 88%).
High Performance Liquid Chromatographic Determination of Lactose in Milk
Authors: West Leslie G , Llorente Marie A
Published: February 2020

A rapid and simple high performance liquid chromatographic method for the determination of lactose in milk was developed. Samples were diluted with 0.5% perchloric acid and centrifuged, and an aliquot of the supernate was mixed with acetonitrile. Lactose was separated on a 10 μm particle-size silica column with aqueous acetonitrile as the mobile phase. The recovery of lactose from whole, skim, and chocolate milk averaged 99.2, 101.1, and 100.4%, respectively. Coefficients of variation for routinely performed duplicate determinations are between 1.0 and 1.5%.
Spectrophotometric Determination of Phosphorus in Certifiable Straight Color Additives: Collaborative Study
Authors: Brammell Wallace S ,   Collaborators:, Arozarena C , Hunter J , Kiernan H G , King J H , Leon M , Schoneker D R , Zyren J
Published: February 2020

A simple and rapid spectrophotometric method was developed for determining the total phosphorus content of certifiable straight color additives. The dye sample is mixed with a cellulose powder and MgO mixture, and ashed at 500°C in a small Pyrex beaker in a muffle furnace. The ash is dissolved in vanadomolybdic acid reagent and filtered through glass wool, and the absorbance of the resulting yellow molybdovanadophosphoric acid solution is measured at 400 nm. The total phosphorus content of the sample, expressed as percent Na3PO4, is determined from a standard curve. Recovery of phosphorus added as KH2PO4 to 39 different dyes in amounts equivalent to 0.300% Na3PO4 ranged from 95.3 to 106.8%, averaging 100.6%. In the collaborative study, 7 laboratories successfully performed duplicate analyses of 6 different dyes (D&C Orange No. 5, D&C Yellow No. 8, FD&C Blue No. 2, FD&C Red No. 3, FD&C Red No. 40, and FD&C Green No. 3). The mean values found ranged from 0.325 to 6.86% Na3PO4. In general, the accuracy and reproducibility of the method were satisfactory, with single determination coefficients of variation ranging from 3.76 to 9.60%. The method was adopted official first action.
Gas-Liquid Chromatographic Determination of Tetradif on Technical and Formulations: Collaborative Study
Authors: Rossum Bram Van , Martijn Albertus , Launer James E ,   Collaborators:, Calamita E C , Oliva M De , Prima S Y Di , Gassola L , Gotz G , Hitos M P , Magallanes M , Pavel K , Poulingue P , Povlsen H H , Rasero F Sanchez , Zeiser O
Published: February 2020

The gas-liquid chromatographic determination of tetradifon technical and formulations was collaboratively studied in duplicate with 12 laboratories. Six samples were dissolved in dichloroethane with n-hexacosane as the internal standard, chromatographed on a column of 3% SE-52, and detected by flame ionization. The average coefficients of variation were 1.2% for the 2 technical samples, 1.6% for the 2 wettable powders, and 1.5% for the 2 emulsifiable concentrates. The method has been adopted official first action.
Spectrophotometric Determination of Atropine Sulfate in the Presence of Phenylmercury (II) Acetate
Authors: Wahbi Abdel Aziz M , Barary Magda
Published: February 2020

Two-component spectrophotometric method of analysis using 2 wavelengths, the method of least squares using absorbances, the method using 2-orthogonal function coefficients, and the method of least squares using orthogonal function coefficients have been applied to the determination of atropine sulfate in the presence of phenylmercury (II) acetate, compounds whose spectra overlap. The first method gave erroneous results; the second method gave satisfactory results for synthetic mixtures. The fourth method was superior, especially in the presence of irrelevant absorption. It has been successfully used for determining atropine sulfate in injection solutions in which a cubic irrelevant absorption was present. Results were in good agreement with those obtained by the official method.
High Performance Liquid Chromatographic Determination of Methapyrilene Hydrochloride in Feed and Sleep Aid Tablets
Authors: Shaikh Badaruddin , Hallmark Margarette R
Published: February 2020

Methapyrilene hydrochloride (MP·HCl) was extracted from feed with methanol and determined by reverse phase partition chromatography in less than 15 min, using isocratic elution with acetonitrile-1.1% ammonium carbonate (1 + 1) as the mobile phase. This procedure was tested on feed treated with MP·HCl at levels of 125,500, and 2000 ppm. Recoveries were 104,95, and 96% with coefficients of variation of 2.4,1.6, and 0.6%, respectively. MP·HCl in feed was stable for 14 days. This method was also successfully used to determine MP·HCl in 3 sleep aid tablets.
Comparative Efficiency of Brilliant Green, Bismuth Sulfite, Salmonella-Shigella, Hektoen Enteric, and Xylose Lysine Desoxycholate Agars for the Recovery of Salmonella from Foods: Collaborative Study
Authors: Andrews Wallace H , Poelma Paul L , Wilson Clyde R ,   Collaborators:, Abeyta C , Chu G S , Cruz L , Dorrett L , English L , Estela L A , Guarino P , Hayden M A , Haymond R E , Heagy J , Hoffman C D , Kallander K , Krout D J , Landry W L , Latt T , Ludwig S G , Martinez E E , McDonald R L , McKee C R , Melanson D E , Otto L A , Palmieri M J , Roderick C N , Sado P N , Sawai E , Stout D K , Tardio J L , Tom J , Twohy C W , Wagner D , White W D , Wong P
Published: February 2020

The relative efficiency of brilliant green (BG), bismuth sulfite (BS), Salmonella-Shigella (SS), xylose lysine desoxycholate (XLD), and Hektoen enteric (HE) agars for the recovery of Salmonella from 5 foods was collaboratively studied in 11 laboratories. The analytical efficiency of various paired combinations of the 5 agars was statistically compared according to 3 parameters: (1) productivity or recovery of Salmonella, (2) rate of enumeration of cultures that were false positive for Salmonella, and (3) rate of enumeration of false-negative reactions. In descending order of productivity, the sequential rankingwasBS, XLD, HE, BG, and SS agars. In ascending order, the rates of false-positive reactions based on a statistical analysis of paired agar combinations was HE, BS, BG and XLD (tie), and SS agars. Analogously, in ascending order, the sequence of false-negative reaction rates was BS, XLD, HE, BG, and SS agars. The combination of BS, XLD, and HE agars is more efficient for recovery of Salmonella from foods than is the present official combination of BG, BS, and SS agars. The revision of official final action method 46.054 to replace the combination of BG, BS, and SS agars with a combination of BS, XLD, and HE agars has been adopted official first action.
X-Ray Powder Diffraction Data for Nine Medicinal 2-Imidazolines
Authors: Owen John T R , Kountourellis John E , Underwood Frank A
Published: February 2020

X-ray powder diffraction data for nine 2-imidazolines have been obtained by the powder dif f ractometer and by the photographic Debye-Scherrer techniques. The data for individual 2-imidazolines are tabulated in terms of lattice spacings (d in Å) and the relative intensities of lines. The best method of packing for powder diffraction was investigated. It was advantageous to use chromium K∝ radiation in the Debye-Scherrer technique.
Spectrophotometry Determination of Procaine Hydrochloride in Presence of 4-Aminobenzoic Acid, Using a Combined Polynomial Method
Authors: Wahbi Abdel-Aziz M , Belal Saied , Bedair Mona , Abdine Hassan
Published: February 2020

A method is presented for the determination of procaine hydrochloride without prior separation from degradation products, using the combined polynomial method. Thus, pw (= 3p2 + 4p3) calculated over the wavelength range 272-316 nm at 4 nm intervals, using 12-point orthogonal polynomials, was linearly related to concentration (0.3-1.3 mg/100 mL), reproducible (rel. std dev. 0.88%), and independent of degradation products. Mean percent recovery for 6 mixtures of procaine hydrochloride and degradation products was 100.49 ± 1.33. The relationship log c% vs time for a solution in pH 10 buffer was linear with aslope of −0.171/day.
Gas-Liquid Chromatographic and Gas-Liquid Chromatographic-Mass Spectrometric Determination of Fenvalerate and Permethrin Residues in Grasshoppers and Duck Tissue Samples
Authors: Reichel William L , Kolbe Elizabeth , Stafford Charles J
Published: February 2020

A procedure is described for determining fenvalerate and permethrin residues in grasshoppers and duck tissues. Samples are Soxhlet-extracted with hexane and cleaned up by gel permeation chromatography with an in-line alumina column. Samples are analyzed by gas-liquid chromatography with electron capture detection, and confirmed by gas-liquid chromatography-mass spectrometry. The average recovery from fortified tissues was 97%.
Rapid Cleanup Procedure for Gas-Liquid Chromatographic Determination of Chlorpyrifos-Methyl Residues in Cat Food
Authors: Simonaitis Richard A , Cail R Spencer , Zehner James M
Published: February 2020

A simple and rapid gas-liquid chromatographic (GLC) method was developed for the determination of residues of chlorpyrifos-methyl in dry cat food. Cat food fortified with chlorpyrifos-methyl was extracted with acetone and cleaned up on a modified acetonitrile-on-Florisil partitioning column. The chlorpyrifos-methyl was determined by GLC with a flame photometric detector. Results were compared with those for known standards that had undergone the same cleanup procedure. The quantitative electronic integration limit of determination was 0.03 ppm. Average recoveries for 5 analyses at fortification levels from 0.052 to 51 ppm ranged from 90 to 102% and averaged 97%.
Volatile N-Nitrosamines in Dried Foods
Authors: Sen Nrisinha P , Seaman Stephen
Published: February 2020

An investigation was carried out to determine the levels of volatile Af-nitrosamines in several dried food commodities such as malt, instant skim milk powder, infant formula containing milk powder, instant coffee, soup and soup bases, and baby cereals. The method involves vacuum distillation of the sample from 3N KOH or 1% sulfamic acid, followed by extraction of the aqueous distillate with dichloromethane. The dichloromethane extract is then washed with an acidic buffer (to remove amines), dried over anhydrous sodium sulfate, concentrated in a Kuderna-Danish concentrator, and analyzed by gas-liquid chromatography, using a thermal energy analyzer. Detection limit is 0.1-0.5 ppb. Of the samples analyzed thus far, all malts (22 samples) and instant skim milk powders (11 samples) were positive for Af-nitrosodimethylamine (NDMA); average levels were 7.4 ppb (1.3-67.0 ppb) and 0.4 ppb (0.3-0.7 ppb), respectively. Traces of NDMA and/or JV-nitrosopyrrolidine were also detected in 3 of 20 dried soups and 5 of 10 instant coffees analyzed. Traces of NDMA and/or AT-nitrosopiperidine (NPIP) were detected in 3 of 8 powdered infant formulas. All 4 baby cereal samples were negative. The identity of NDMA in 14 samples of malt and that of NDMA and NPIP in an infant formula was confirmed by gasliquid chromatography-mass spectrometry; identity of N-nitrosamines in 3 instant coffees and 1 infant formula was independently verified by high pressure liquid chromatographic analysis.
Anomalies in the Mass Spectrum of N-Nitrosopyrrolidine
Authors: Libbey Leonard M , Scanlan Richard A
Published: February 2020

Several anomalies in the published standard mass spectrum of JV-nitrosopyrrolidine (NPYR) were pointed out and a new standard spectrum was presented. It was suggested that the published standard was partially thermally degraded, perhaps by an overheated inlet line or interface to the mass spectrometer. Specific anomalies thought to be due to overheating included a marked decrease in the relative intensity of m/z 100 (M+) and a concomitant increase in m/z 30 and m/z 69. The large ion at m/z 28 could not be attributed to overheating, nor to an air leak; rather it is part of the normal spectrum for NPYR.
Analysis of Laboratory Animal Feed for Toxic and Essential Elements by Atomic Absorption and Inductively Coupled Argon Plasma Emission Spectrometry
Authors: Blakemore William M , Billedeau Stanley M
Published: February 2020

Analytical procedures are described for the determination of arsenic, cadmium, calcium, copper, lead, mercury, selenium, and zinc in animal feed. Mercury is determined by digesting the feed sample in a mixture of concentrated nitric and sulfuric acids with vanadium pentoxide added as an oxidation catalyst, reducing with stannous chloride, and sweeping the elemental mercury into an absorption tube for measurement by atomic absorption (AA) spectrophotometry. Arsenic and selenium are determined simultaneously by digesting the sample with a mixture of concentrated nitric, sulfuric, and perchloric acids; the hydrides of arsenic and selenium, which are formed with the addition of sodium borohydride, are swept into an argon-hydrogen flame for analysis by AA. A low temperature ash is prepared and dissolved in 1N HNO3 for the analysis of calcium, copper, and zinc by emission spectroscopy using the inductively coupled argon plasma source; the same solution is used for the determination of cadmium and lead by flameless AA. Animal feed spiked with 3 levels of each of the 8 elements gave recoveries that ranged from 80 to 107%.
Determination of Norflurazon Residues in Mixed Crop Matrices
Authors: Winkler Victor W , Patel Jayanti R , Januszanis Mary , Colarusso Marjorie
Published: February 2020

A method for determining norflurazon residues in mixed crop matrices is described. The method includes methanol Soxhlet extraction, hexane wash, addition of 10% saline, methylene chloride extraction, concentration, preparative thin layer chromatography of 10% sample aliquot, and resuspension of sample zone for gas-liquid chromatographic analysis. The lower level of electron capture detection is 0.01 ppm. Recoveries for 0.08 ppm spiked samples of cottonseed; soybean seed and foliage; peanut seed plus hulls and foliage,; orange and tangerine; lemon; apple and peach; and soil are generally greater than 80%.
Thin Layer Chromatographic Determination of Methyl Parathion as Paraoxon by Cholinesterase Inhibition
Authors: Bhaskar Sana Udaya , Kumar Nanguneri V Nanda
Published: February 2020

A simple, sensitive, and rapid method is described for the quantitative estimation of nanogram amounts of methyl parathion (O,O-dimethyl O-p-nitrophenyl phosphorothioate) as methyl paraoxon (O,O-dimethyl O-p-nitrophenyl phosphate) on thin layer chromatograms. Methyl paraoxon is detected by pig liver acetone powder cholinesterase inhibition, using p-nitrobenzenediazoniumfluoroborate as the chromogenic reagent. Commercial pig liver acetone powder is more advantageous than raw liver sources because it is readily available and can be preserved indefinitely. About 0.1 ng methyl parathion can be detected, and amounts from 5 to 50 ng can be quantitatively estimated.
Comparison of Three Methods for Determination of Sulfamethazine in Swine Tissues: Collaborative Study
Authors: Malanoski Anthony J , Barnes Charlie J , Fazio Thomas
Published: February 2020

An interlaboratory study of 3 methods for the determination of sulfamethazine in swine muscle and liver tissue was conducted. A gas chromatographic (GC), a combined gas chromatographic-mass spectrometric (GC/MS), and a colorimetric method were evaluated. Four fortified and 2 incurred levels of sulfamethazine ranging from 0.00 to 0.45 ppm were studied. The study revealed that the GC/MS procedure provides the most reliable data and that the GC method provides acceptable data w i t h the incorporation of appropriate controls. The recoveries for the GC/MS method typically ranged from 90 to 100% for swine liver and muscle. The GC and GC/MS methods have been adopted official first action.
Liquid and Gas Chromatographic Analysis of Diethyl Phthalate in Water and Sediment
Authors: Payne William R , Benner Jacquelyn E
Published: February 2020

Diethyl phthalate was determined in water and sediment by high performance liquid chromatography (HPLC) and in water by gas-liquid chromatography with electron capture detection (GLC-ECD). Water samples were extracted with hexane, using a high-speed homogenizer-ultrasonic apparatus and a test tube mixer. Sediments were Soxhlet-extracted using acetonitrile. For HPLC, diethyl phthalate was determined in normal phase mode using a Zorbax-CN column, a 2% isopropanol-hexane solvent system, and a UV variable wavelength detector. For GLC-ECD, a 3% SE-30 Gas-Chrom Q column with a 63Ni electron capture detection system was used. Recoveries from fortified samples ranged from 93.9 to 98.0% for water atO.Ol-0.50 ppm, and from 90.0 to 93.6% for sediment atO.2-2.Oppm.
Spectrophotometric Determination of Menadione and Menadione Sodium Bisulfite
Authors: Sidhom Madiha B , El-Kommos Michel E
Published: February 2020

A spectrophotometric method is described for the determination of menadione and menadione sodium bisulfite in bulk and in solution for injection. The method measures the intensity of the violet color (λmax 540 nm) developed when menadione reacts with thiosemicarbazide in alkaline medium. Beer's law is obeyed in the concentration range 4-40 μg/m L (r = 0.9995). The method is simple, sensitive, and particularly suited for routine analysis of official menadione sodium bisulfite injection. Results are comparable with the USP method.
Spectrophotometric Determination of Oxazepam and Dipyridamole in Two-Component Mixtures
Authors: Korany Mohamed A , Haller Rolf
Published: February 2020

The λpj method is applied to simultaneous determination of oxazepam and dipyridamole in 2-component mixtures. Authentic mixtures and tablets containing oxazepam and dipyridamole were assayed by measuring the absorbances in 0.1N H2SO4 and 0.05M borax solutions and calculating the λp2 at 2 wavelength sets: 272-312 nm (at 8 nm intervals) and 288-328' nm (at 8 nm intervals). The concentration is evaluated by solving a pair of simultaneous equations. The results obtained are reasonably reproducible with a coefficient of variation less than 2%. The proposed method is compared with the λA modification of Vierordt's method of 2-component analysis. The λpj method gave more accurate and precise results.
Derivatization and Cleanup Improvements in Determination of Residues of Glyphosate and Aminomethylphosphonic Acid in Blueberries
Authors: Guinivan Richard A , Thompson Neal P , Wheeler Willis B
Published: February 2020

A new method based on development of the 2-chloroethyl N-heptafluorobutyryl derivatives of glyphosate and its major metabolite aminomethylphosphonic acid is reported for fortified blueberry samples. The concentrated aqueous extract is chromatographed on a gel permeation column in a low pH eluant. Under these conditions, sugar is eliminated by permeation and pigments are strongly adsorbed. Additional sugar is eliminated with a small cation exchange column and then the sample is easily dried and derivatized. The derivatized compounds are extracted from an aqueous environment with hexane and analyzed by gas chromatography with electron capture detection. This procedure requires significantly less sample handling time and provides greater sensitivity for glyphosate than the commonly used procedure recommended by EPA.
Automated High Pressure Liquid Chromatographic System for Determination of Mannitol, Sorbitol, and Xylitol in Chewing Gums and Confections
Authors: Samarco Eugene C , Parente Ernest S
Published: February 2020

A rapid, precise, and reproducible automated high pressure liquid chromatographic method was developed to determine xylitol in the presence of mannitol and sorbitol in chewing gums and confectionery products. A mobile phase of water and methanol elutes the polyols simultaneously from a cation-exchange column without pretreatment or derivatization. Injections into the liquid chromatograph were made by an autosampler, and data reduction was performed with a programmable electronic integrator. Average recoveries for one level each of mannitol, sorbitol, and xylitol in 6 replicate samples prepared by the standard addition technique were 102.5,100.5, and 100.7%, respectively.
Recovery of Eggs of Two Parasitic Nematodes, Ascaris sp. and Trichuris sp.: Interlaboratory Study
Authors: Rude Richard A , Bier Jeffrey W , Jackson George J , McClure Foster D
Published: February 2020

An interlaboratory study was conducted to determine the effectiveness of the Nacconol ether centrifugation method for recovering parasitic nematode eggs from 3 contaminated products: a crop (cabbage), a sludge fertilizer (Milorganite), and a sewage effluent (Minneapolis). Six replicate samples for each of the 3 products were seeded with eggs at 3 different levels: 200 Ascaris suis and 8 Trichuris muris; 15 A. suis and 15 T. muris; 8 A. suis and 180 T. muris. Recovery was low for all samples except sewage effluent, in which recoveries greater than 100% in 2 samples resulted from the misidentification of arthropod eggs as Ascaris sp. The average mean percent recovery for the other samples was 22.53. Repeatability for replicate samples and reproducibility of results by individual laboratories were poor, and the method is not recommended for quantitative estimates of nematode egg contamination of foods and food-contact materials. However, the Nacconol ether centrifugation method can be used as an all-or-none test. (Only 13% of 1146 counts were falsely negative.) Of 69 samples, only 4 were falsely negative for A. suis eggs and only 1 was falsely negative for T. muris eggs in counts of 6 replicates.
Accuracy of Pesticide Reference Standard Solutions. Part II. Chemical Stability Under Four Storage Conditions
Authors: Hodgson David W , Thompson John F , Watts Randall R
Published: February 2020

A study was undertaken to assess the long-term chemical stability of dilute standard pesticide solutions of 4 compound classes. The solutions were studied under 4 storage conditions: freezer at —15°C; refrigerator at 3°C; ambient temperature in the dark; and ambient temperature on the bench top exposed to fluorescent and natural light. Pesticide compounds including 27 organochlorines, 20 organophosphates, 10 triazines, and 13 carbamates were monitored for periods of 6 months to 2 years. Most of the compounds were stable (<10% decomposition) under all conditions for the full length of the study. Solutions of CDEC, butylate, and disulfoton, however, decomposed when stored under all storage conditions. Solutions of carbaryl, methiocarb, and carbofuran decomposed when stored at ambient laboratory temperature with exposure to light. Recommendations are made for formulating solvents, storage, and practical shelf life of high concentration stock solutions and dilute gas chromatographic working standards representing 4 pesticide classes
Microbial Hazards Associated with Bean Sprouting
Authors: Andrews Wallace H , Mislivec Philip B , Wilson Clyde R , Bruce Verneal R , Poelma Paul L , Gibson Regina , Trucksess Mary W , Young Kathryn
Published: February 2020

The behavior of microorganisms was studied in mung beans and alfalfa seeds before and after germination in modified, commercially available bean-sprouting kits. The microorganisms were enumerated by the aerobic plate count (APC) and by total yeast and mold count procedures. Salmonella species were artificially inoculated into selected samples and were enumerated by the most probable number (MPN) method. After germination of the beans or seeds into mature sprouts, significant increases were noted in APCs and in MPN values of Salmonella species. Although counts of yeasts and molds did not increase significantly after germination, these samples showed an increase in toxic Aspergillus flavus and potentially toxic Alternaria species. The presence of toxic Penicillium cyclopium molds also increased substantially in 5 samples of a single brand of mung beans. Analysis of selected sprout samples, however, showed no presence of aflatoxin.
Safe Storage Vessel for Small Quantities of Diazomethane
Authors: Barnes Charlie J , Jones James T , Matusik Jean E
Published: February 2020

Two relatively safe, inexpensive, and easily fabricated vessels for the storage of small quantities of ethereal diazomethane are described
Analytical Methods for Microbiology in the Next Decade
Authors: Feldman John
Published: February 2020

As microbiologists develop and modify methods and turn to automated equipment to decrease analysis time, the precision and accuracy of the methods must be ensured through collaborative study. Rapid, validated methods are needed in many areas. Sterility testing and the use of biological indicators are among subjects of interest to FDA and industry. These groups are also studying particulate analysis. The limulus amebocyte lysate test is being considered for use in detecting endotoxins in drugs and medical devices, in diagnosing illness, and in assessing the microbiological quality of foods and water. Reliable methods are needed for detecting viruses in foods to assure a safe food supply. Studies are needed on the Vibrionaceae to better understand the mechanisms of invasiveness and host response. Methods must also be developed to study pathogens in the water and food supply.
High Pressure Liquid Chromatographic Determination of Glycyrrhizic Acid or Glycyrrhizic Acid Salts in Various Licorice Products: Collaborative Study
Authors: Vora Peter S ,   Collaborators:, Estes H , Grigor Dr , Hodge B , Hurst W J , LeBlanc D , Shuford C , Walker K , Zimmermann M
Published: February 2020

A collaborative study determining glycyrrhizic acid or glycyrrhizic acid salts content of various licorice products has been conducted using high pressure liquid chromatography (HPLC). Five samples containing various concentrations of glycyrrhizic acid were analyzed in blind replicates by 8 collaborators. The results indicate excellent repeatability and reproducibility with coefficients of variation less than 7.5%. In addition, this method allows the determination of glycyrrhizic acid in less than 15 min compared with 3 days for the conventional gravimetric and colorimetric methods. The method has been adopted official first action.
Evaluation of Silica and Polar Bonded Columns for Liquid Chromatographic Analysis of Temephos Formulations
Authors: Mount Dwight L , Miles James W
Published: February 2020

In the course of development of an HPLC method for determination of temephos in technical grade temephos and its formulations, a variety of columns and solvent systems were evaluated. Three satisfactory methods evolved and were evaluated for reproducibility, convenience, cost, and optimum resolution of active ingredient from possible impurities. After consideration of advantages and disadvantages of each system, a method based on the use of a silica gel column eluted with ethyl acetate-hexane (10 + 90) and p-nitrophenyl p-nitrobenzoate as internal standard was selected for testing in an international collaborative trial.
Gas Chromatographic Determination of Synthetic Musk (7-Acetyl-6-Ethyl-1,1,4,4-Tetramethyltetralin) in Fragrances
Authors: Wisneski Harris H , Yates Ronald L , Davis Henry M
Published: February 2020

A gas chromatographic method has been developed for the determination of the synthetic fragrance musk, 7-acetyl-6-ethyl-1,1,4,4-tetramethyltetralin (AETT). The fragrance is first added to water and extracted with ether to separate the fragrance oil from the water-alcohol mixture. The AETT, present in the ether-soluble fraction, is purified further by preparative high pressure liquid chromatography (HPLC). The AETT in the collected HPLC fraction is then determined by gas chromatography using external standardization. Recoveries from samples spiked with AETT at levels ranging from 100 to 1000 μg/mL varied from 80 to 96% with an average of 90%. AETT was verified in each sample by gas chromatography/mass spectrometry.
High Performance Liquid Chromatographic Determination of Vitamin D in Fortified Milks, Margarine, and Infant Formulas
Authors: Thompson James N , Hatina George , Maxwell William B , Duval Suzanne
Published: February 2020

Fortified milks were saponified overnight at room temperature with 1% ethanolic pyrogallol and KOH. The digest was extracted with hexane after adding water and ethanol, and the extract was washed consecutively with 5% KOH, water, and 55% aqueous ethanol to remove polar lipids. After evaporation, the residue was first chromatographed on a column of 5 μm silica. A fraction containing vitamin D was collected, evaporated, and rechromatographed on a reverse phase column for the separation and quantitation of vitamins D2 and D3. Recovery was 96-99% and the coefficient of variation was 3% (8 replicates). Infant formula was diluted and then saponified and extracted as in the analysis of milk. Margarine was saponified by shaking overnight with 1% ethanolic pyrogallol and 80% KOH. Water and ethanol were added to the digest before extraction. Extracts from formula and margarine were chromatographed as milk except, before HPLC, the extract was dissolved in isopropanol-hexane (1 + 99) and passed through 5 cm alumina in a Pasteur pipet, and the concentration of isopropanol in the first high performance liquid chromatographic (HPLC) solvent system was halved to improve the separation of vitamin D from other absorbing lipids. Usually several peaks were obtained during the final HPLC analysis, and the identification of vitamins D2 and D3 was less certain than in the analysis of milk. The coefficients of variation for formula and margarine were 6% (5 replicates) and 9% (6 replicates), respectively.
Screening Test for Sulfamethazine and Sulfathiazole in Swine Liver
Authors: Parks Owen W
Published: February 2020

A screening method is described for estimation of sulfamethazine and sulfathiazole residues in swine livers. Tissues are homogenized with CHCl3-ethyl acetate (1 + 1). The drugs are extracted from the organic solvent with pH 10 carbonate buffer and back-extracted into dichloromethane, as an ion-pair with tetrabutylammonium hydroxide, without pH adjustment. Following evaporation of the solvent, the residue is dissolved in methanol, subjected to thin layer chromatography, and detected by the Bratton- Marshall reaction. Recoveries of sulfamethazine and sulfathiazole, determined by high pressure liquid chromatography, were 50.8 and 42%, respectively, with coefficients of variation of 4.2 and 4.7%.
Simple, Low-Cost Method for Determination of Selected Chlorinated Pesticides in Fat Samples
Authors: Waliszewski Stefan M , Szymczyński Grzegorz A
Published: February 2020

A method is described for the quantitative and qualitative determination of selected chlorinated pesticides in fat samples. Pesticide residues are extracted with petroleum ether and separated from fat with concentrated H2SO4 instead of the commonly used adsorbents Florisil, alumina, or silica gel. Residues were analyzed by gas chromatography with electron capture detection. Recoveries of fortified samples were approximately 100%.
Gas-Liquid Chromatographic-Thermal Energy Analyzer Determination of N-Nitrosodimethylamine in Beer: Collaborative Study
Authors: Sen Nrisinha P , Seaman Stephen , Bickis Mikelis ,   Collaborators:, Castegnaro M , Ellen G , Fazio T , Fiddler W , Fine D H , Herwig W C , Issenberg P , Lacey A B , Massey R , O’Brien T , Scanlan R , Thomas G , Thomsen J
Published: February 2020

The GLC/TEA method for N-nitrosodimethylamine (NDMA) in beer was studied collaboratively by 13 laboratories from 7 countries. Collaborators were asked to analyze a total of 10 randomly labeled samples of beer consisting of the following duplicates: a naturally contaminated commercial beer; a beer extremely low (ca 0.1 ppb) in NDMA; and the low NDMA beer spiked with 0.5,1.9, and 5.0 ppb NDMA. The pooled repeatability and reproducibility coefficients of variation (CV) for all samples were 17% and 27%, respectively. However, when data from 2 laboratories (outliers) were omitted, the corresponding CV values improved considerably (11% and 15%, respectively). Variance analysis showed the presence of a significant laboratory-sample interaction when all data were used for analysis, but this interaction disappeared when data from the 2 outlying laboratories were excluded. The pooled percent recovery of the overall method (omitting outliers) was 101.4 ± 3.5. All the laboratories detected NDMA in the low NDMA beer. The method was adopted official first action.
Adsorption of 2,4-Dichlorophenoxyacetic Acid on Glassware as Source of Error in 2,4-D Analysis
Authors: Kan Gordon Y P , Mah Fred T S , Wade Norman L
Published: February 2020

Loss of 2,4-dichlorophenoxyacetic acid (2,4-D) by adsorption on Pyrex evaporating flasks and flint glass bottles was studied. 2,4-D may be quantitatively recovered by direct methylation with diazomethane in Pyrex evaporating flasks; it may also be desorbed with methylene chloride in the presence of strong H2SO4. This step must be taken when 2,4-D is transferred from one glass vessel to another to ensure accuracy of data.
International Mycotoxin Check Sample Program: Part I. Report on Laboratory Performance for Determination of Aflatoxins B1, B2, G1, and G2 in Raw Peanut Meal, Deoiled Peanut Meal, and Yellow Corn Meal
Authors: Friesen Marlin D , Garren Liliane
Published: February 2020

Three aflatoxin-contaminated samples (raw peanut meal, deoiled peanut meal, and yellow corn meal) were analyzed by 121 laboratories in 31 countries. Sufficient data were obtained to permit a statistical comparison of the performance of laboratories using the BF, CB, and EEC methods and those using high performance liquid chromatography (HPLC) for quantitation. No significant differences were found between means for laboratories using these 4 methods for the analysis of raw peanut meal or yellow corn meal. However, for deoiled peanut meal, means were significantly different for laboratories using the BF method compared with the CB or EEC methods for B1 and B2, and for laboratories using the CB method compared with HPLC methods for G2.
High Performance Liquid Chromatographic Quantitation of Aflatoxin Metabolites in Animal Tissues
Authors: Gregory Jesse F
Published: February 2020

A previously reported reverse phase high performance liquid chromatographic (HPLC) procedure was modified to permit the determination of the parent aflatoxins and various free and conjugated metabolites in animal tissues. The modified procedure was based on HPLC analysis of duplicate portions of a sample extract which had been prepared with and without treatment with trifluoroacetic acid (TFA). TFA catalyzes the conversion of aflatoxins G1, B1, M1, and Q1 to the fluorescent derivatives G2a, B2a M2a, and Q2a. Aflatoxicol, which exhibited a sharp fluorescent peak in its native state, eluted as a tailing peak with weaker fluorescence following TFA treatment. Acid hydrolysis of the aqueous phase of tissue samples permitted the analysis of water-soluble conjugated forms of the various aflatoxins. Analysis of fluorescence spectra of manually collected HPLC fractions qualitatively supported the accuracy of the method. Representative data on the distribution of aflatoxins in turkey liver following ingestion of an experimentally contaminated ration are presented.
Gas-Liquid Chromatographic Determination of Nonpolar Organochlorine Pesticide Residues in a Crude Vegetable Oil and Its Refinery By-Products
Authors: Young Susan J V , Kamps Laverne R
Published: February 2020

A crude soybean oil, several of its refinery by-products (described as soapstock, deodorizer distillate, and clabber stock), and the completely refined oil were analyzed for pesticide residues. Fourteen organochlorine pesticides and pesticide metabolites were found in the deodorizer distillate; 5 of these were also found in the clabber stock. Levels in these byproducts ranged from 0.3 to 8 ppm. Only endrin and dieldrin were detected in the crude oil at levels of 0.01 and 0.05 ppm, respectively. Forty to 150 times these levels were found in the deodorizer distillate and clabber stock. Pesticide residues were not detected in the refined oil or in the soapstock at limits of detection for dieldrin of about 0.01 and 0.1 ppm, respectively. The method used by the Food and Drug Administration to analyze fats and oils for multiple organohalogen pesticide residues was inadequate for the extraction of pesticide residues from vegetable oil refinery by-products. The method used to analyze the crude vegetable oil and the refinery by-products involved dissolution of the oil samples in ethyl acetate- toluene, filtration if necessary, cleanup by gel permeation chromatography, and then Florisil column chromatography. The oil was isolated from aqueous-oil mixtures by extraction with hexane before analysis. The crude soybean oil was fortified with 12 organohalogen pesticides and Aroclor 1254 at levels of 0.5-3.7 ppm. Recoveries ranged from 83 to 102%.
High Performance Liquid Chromatographic Determination of Intermediates and Reaction By-Products in FD&C Yellow No. 5: Collaborative Study
Authors: Cox Elizabeth A , Mcclure Foster D ,   Collaborators:, Bell S , Beswick R , Bischof R , Gasper G , Gibson L , Goldberg A , Gosselè J , Gunn M , King J , Penta F , Richfield-Fratz N , Shah D , Sutherland A , Young R
Published: February 2020

Eight laboratories participated in a collaborative study of an ion exchange high performance liquid chromatographic procedure for determining the intermediates and 2 reaction by-products in FD&C Yellow No. 5: phenylhydrazine-p-sulfonic acid (PHSA), sulfanilic acid (SA), l-(4-sulfophenyl)-3- carboxy-5-hydroxypyrazolone (PyT), l-(4-sulfophenyl) - 3 -ethylcarboxy-5-hydroxypyrazolone (EEpyT), and 4,4'-(diazoamino)-dibenzenesulfonic acid (DAADBSA). The repeatability and reproducibility standard deviations (absolute) found in the study were 0.0134 and 0.0263 for PHSA at the 0.1% level, 0.0246 and 0.0256 for SA at the 0.2% level, 0.0124 and 0.0149 for EEpyT at the 0.1% level, 0.0212 and 0.0258 for PyT at the 0.2% level, and 0.0234 and 0.0373 for DAADBSA at the 0.2% level. The method was adopted official first action.
Innovations in Atomic Absorption Spectrophotometry with Electrothermal Atomization for Determining Lead in Foods
Authors: Rains Theodore C , Rush Theresa A , Butler Therese A
Published: February 2020

A simple and rapid method is described for the determination of lead in foods. The samples are digested in HNO3, HF, and HCIO4 and then the lead is determined by atomic absorption spectrophometry using an electrothermal atomizer with the L'vov platform. Interferences and ways to improve the precision and accuracy of the analysis were studied. Matrix modification using 1% ammonium phosphate alleviated most interferences encountered. The precision and accuracy of the method was evaluated using NBS SRM 1570 Spinach and SRM 1566 Oyster Tissue. The values obtained are in good agreement with the certified values.
Differential Pulse Polarographic Determination of Iodine in Thyroid Tablets: Collaborative Study
Authors: Holak Walter ,   Collaborators:, Baetz R , Beavin P , Gable P , Hebert R , Illuminati J , Jennings J , Panaro K , Poplawski T
Published: February 2020

A differential pulse polarographic (DPP) method for the determination of iodine in thyroid and thyroid preparations was collaboratively studied by 8 laboratories. The overall concentration of iodine in commercial thyroid tablets containing ¼, 1,2, and 5 gr. of declared thyroid was 0.196%. The overall repeatability and reproducibility standard deviations were 0.0043 and 0.0067, respectively, and the corresponding coefficients of variation were 2.18 and 3.41%, respectively. The results obtained by the DPP method agreed with those obtained by the U.S. Pharmacopeia XX method at the various concentrations of declared thyroid studied. The DPP method has been adopted official first action.
Manual Salicylate-Hypochlorite Procedure for Determination of Ammonia in Kjeldahl Digests
Authors: Fukumoto Helen E , Chang George W
Published: February 2020

The determination of nitrogen in Kjeldahl digests of urine and feces has been simplified by using a manual spectrophotometric method with salicylate and hypochlorite. It neither involves the hazards of the phenol-hypochlorite method, nor requires an automated analyzer. We determined the conditions which minimize the need for precise timing and neutralization of acidic digests and obtained coefficients of variation of about 0.8%. Agreement between the spectrophotometric method and the conventional micro-Kjeldahl method was excellent; a correlation coefficient of 0.9992 and a coefficient of variation of the estimate of 2.1% were obtained. This method is well suited for a laboratory with a moderate volume of samples. We could process at least 200 digests per day, in contrast with the 60 per day which we had previously done by the Kjeldahl distillation and titration.
Defatting Technique for Two Ground Spices Using Simple Reflux Apparatus: Collaborative Study
Authors: Dent Russell G ,   Collaborators:, Bradicich R B , Dzidowski G , Glaze L , Quaife J
Published: February 2020

A solvent defatting technique was tested for 2 spices which require the same extraction process but different defatting agents. For turmeric, which uses isopropanol as the defatting agent, recoveries of rodent hair and insect fragments were not significantly different from those in the original collaborative study, and this technique is recommended as an alternative to AOAC method 44.122(a). However, for oregano, which uses chloroform as the defatting agent, recoveries of insect fragments were significantly lower by the reflux method. An alternative chloroform pretreatment for oregano, therefore, is not recommended for AOAC 44.122(b). It is suggested that reflux action defatting techniques be considered during the developmental stages of new methods. The technique has been adopted official first action for turmeric.
Gas-Liquid Chromatographic Determination of Fenvalerate Insecticide Residues in Processed Apple Products and By-Products
Authors: Spittler Terry D , Argauer Robert J , Lisk Donald J , Mumma Ralph O , Winnett George ,   Collaborators:, Bogus E , Greco E , Gutenmann W , Marafioti R , Miles E , Wszolek P , Zimmerman L
Published: February 2020

Apples from trees treated in the field at 2-week intervals (9 foliar applications) with the synthetic pyrethroid insecticide fenvalerate (cyano(3-phenoxyphenyL)methyl 4-chloro-alpha-(1-methylethyl)- benzeneacetate) were processed into apple sauce, juice, pomace, and peels plus cores. Gas-liquid chromatographic analysis of the commodities for fenvalerate showed the sauce and juice to be essentially residue-free, the whole apples to contain about 0.4 ppm, and the pomace and peels plus cores to contain about 2 and 1.5 ppm, respectively. Agreement among 5 laboratories using modifications of the same basic method was good.
Recovery of Endogenous Selenium from Fish Tissues by Open System Dry Ashing
Authors: May Thomas W
Published: February 2020

Quantitative recovery of endogenous selenium from fish tissues following dry ashing techniques has not been confirmed. An open system dry ashing procedure, using oxidative fusion with Mg(NO3)2•6H2O in the presence of MgO, was tested for recovery of selenium from National Bureau of Standards (NBS) Reference Materials (tuna and oyster) and selected fish tissues. Recovery after dry ashing and hydride analysis was complete from NBS Bovine Liver, Tuna, and Oyster Tissues, as well as from Food and Drug Administration cod, haddock, perch, and flounder research materials. Endogenous selenium, injected into rainbow trout (Salmo gairdneri) as 75Se, was recovered after ashing from liver, ovaries, gastrointestinal tract, muscle, bile, and carcass, 3 and 10 days post-injection. Results indicate that open vessel oxidative fusion is a rapid, simple technique applicable to quantitative recovery of selenium from organoselenium compounds that exist in various aquatic species. The diluted digestate is readily amenable to conventional hydride generation analysis.