bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid Chromatographic Determination of Residual Styrene in Polystyrene Food Packaging
Authors: Varner Sandra L , Breder Charles V 
Published: February 2020

Abstract
The determination of residual styrene in polystyrene food packaging polymers by a reverse phase liquid chromatographic method is described. The polymer is dissolved in tetrahydrofuran and then reprecipitated with methanol. The filtered solution is chromatographed by using an aqueous tetrahydrofuran mobile phase, and the styrene is detected and quantitated by ultraviolet at 254 nm. The detection limit for the method is about 0.5 ppm styrene on a solution basis and 20 ppm in the polymer. The average recovery of styrene from spiked polymer (about 50–3700 ppm) is 88%. Apparent residual styrene was determined in several commercial products, including rigid polystyrene cups, flexible plastic containers, and several foam products. The monomer levels ranged from about 60 to 2250 ppm.
Lead in Preserved Duck Eggs: Field Screening Test and Confirmation and Quantitation by Atomic Absorption Spectrophotometry and Anodic Stripping Voltammetry
Authors: Krinitz Benjamin , Tepedino Nivia 
Published: February 2020

Abstract
Analysis of preserved duck eggs in this laboratory by acid digestion and atomic absorption spectrophotometry has shown that addition of lead salts to the egg coating to speed the preservation process results in lead in the egg albumen and yolk. The lead levels decrease as the lead passes through successive membranes, i.e., the lead level in the yolk is lower than that in the albumen. A method has been developed for the field screening of preserved duck eggs for the presence of lead in which a portion of the egg coating is shaken with 4% acetic acid, and the resulting solution is tested by a modification of the AOAC dithizone method. A quantitative method for laboratory confirmation of lead in egg albumen and/or yolk has also been developed in which lead is determined by atomic absorption spectrophotometry or anodic stripping voltammetry after closed-system Tefloncup digestion with nitric acid.
Mass Spectral Quantitation of Cocaine HCl in Powders
Authors: Clark Charles C 
Published: February 2020

Abstract
Gas-liquid chromatography (GLC) using a mass spectrometer (MS) as a detector is used for the quantitative determination of cocaine HCl in powders. After the sample is dissolved in methanol containing deuterated cocaine HCl internal standard, an aliquot is injected into the GLC-MS system with the mass spectrometer operating in the scan mode. The cocaine HCl concentration is calculated from the 303/308 m/e ratio. The procedure has a relative deviation of approximately 2.3% and is applicable to samples containing a wide variety of diluents and adulterants.
Pre-enrichment Broths for Recovery of Salmonella from Milk Chocolate and Edible Casein: Collaborative Study
Authors: Poelma Paul L , Andrews Wallace H , Wilson Clyde R ,   Collaborators:, Coles C M , Edwards A W , Hayden M A , Haymond R E , Heagy J , Kallander K , Lappin D , Latt T G , McDonald R L , McKee C R , Mihm J , Palmieri M J , Quinones L , Richter S G , Roderick C N , Sado P N , Sellers R L , Singleton E , Smith M , Tardio J L , Wagner D E , White C H , Williams M P 
Published: February 2020

Abstract
A collaborative study was conducted to compare the relative efficiency of nonfat dry milk with brilliant green dye (NFDM-BG) and buffered peptone water (BPVV) as pre-enrichment broths for recovery of Salmonella from milk chocolate. Lactose broth and modified lactose broth with added 1% NaHCO3 and brilliant green dye were compared as pre-enrichment broths for recovery of Salmonella from edible casein. Two sets of 8 samples each of milk chocolate, containing initial levels of Salmonella ranging from &lt;0.03 to 43 organisms/g, were examined by 13 collaborators. Of 104 determinations, 102 (98.1%) and 100(96.2%) using NFDM-BG and BPW, respectively, were in agreement with sample results of the control laboratory. Two sets of 7 samples each of edible casein, containing initial levels of Salmonella ranging from &lt;0.03 to 93 organisms/g, were also examined by the 13 collaborators. Of 91 determinations, 87 (95.6%) and 88 (96.7%) using lactose broth and modified lactose broth, respectively, were in agreement with sample results of the control laboratory. For recovery of Salmonella, therefore, NFDM-BG pre-enrichment is recommended for milk chocolate, and lactose broth is recommended for casein. The proposed revision of official final action method 46.054-46.067 has been adopted official first action
Simplified Apparatus for Determination of Mercury by Atomic Absorption and Inductively Coupled Plasma Emission Spectroscopy
Authors: Suddendorf Ronald F , Watts James O , Boyer Kenneth 
Published: February 2020

Abstract
A simplified apparatus has been applied to the determination of mercury by cold vapor generation. The equipment consists of a reaction flask incorporating a side arm in which a rubber septum is mounted. A sample solution is injected from a syringe through the rubber septum into the reaction flask, where it is mixed with a stannous chloride reducing solution. The elemental mercury generated is then swept with a carrier gas to the inductively coupled plasma (ICP), an absorption cell of an atomic absorption spectrometer, or a nondispersive UV monitor for determination. Detection limits were 0.00.9 and 0.005 μg with atomic absorption and the UV monitor, respectively, and 0.09 μg with the ICP. Repeatability of the procedure was 1.4% at 0.66 μg injected mercury with the ICP and 5.2% at 0.45 μg injected with atomic absorption. Tuna and halibut samples fortified with from 0.09 to 1.31 μg mercury/g were analyzed by the AOAC official method and the procedure described here. The average mercury recovery was 103% with the ICP, and 99% with the UV monitor and with atomic absorption. The procedure is free from interference by elements commonly present in biological material.
Analysis and Evaluation of Barley Used in the Malt Beverage Industry
Authors: West Dwight B 
Published: February 2020

Abstract
The American Society of Brewing Chemists methods for barley moisture, extract, and potential diastatic power are presented. These methods were reviewed by a Barley Analysis Subcommittee during 1975–1980 and published as recommended procedures. The moisture determination has been adopted as an official first action ASBC-AOAC method.
Colorimetric Alpha-Amylase, Falling Number, and Amylograph Assays of Sprouted Wheat: Collaborative Study
Authors: Mathewson Paul R , Fahrenholz Charles H , Booth Gordon D , Miller Byron S , Pomeranz Yeshajahu ,   Collaborators:, Ahmed S R , Axford D W , Bass E J , Boiling H , Chapman D W , Dot J W , Dur R H , Egber D C , Hempleman E W , Marchyl B , Meredit P , Naga S , Perten H , Perten P , Prasad K , Rubenthaler G L , Sawabe T , Sog L , Spillan P , Sundberg D F , Udy D C , Wyant R N 
Published: February 2020

Abstract
Results are reported of a collaborative study on the determination of sprout damage in wheat. Methods of analysis included falling number, amylograph, and a colorimetric α-amylase assay. Data for the 3 methods were linearly interrelated. Primary source of error for each method was lack of agreement among collaborators. The 3 tests adequately differentiated among sprout damage levels within a single laboratory. The colorimetric test was the most sensitive to change in α-amylase content and appeared to have greater potential for standardization than the other 2 methods
High Pressure Liquid Chromatographic Determination of Aflatoxins in Spices
Authors: Awe Michael J , Schranz John L 
Published: February 2020

Abstract
High pressure liquid chromatography with fluorescence detection is used to determine aflatoxin in 5 common spices. A 10 µm microparticulate silica gel column is used with a dichloromethane-cyclohexane-acetonitrile solvent system to resolve aflatoxins B1, G1, B2, and G1. The fluorescence detector contained a silica gel-packed f lowcell. Samples of black, white, and red pepper, ginger, and nutmeg were extracted according to a previously published method. Recoveries from aflatoxin-free samples of white pepper, ginger, and red pepper spiked with 1-50 µg aflatoxin/kg ranged from 64 to 92%.
Oscillating U-Tube Density Meter Determination of Alcoholic Strength: Analysis of Parameter Errors
Authors: Kovář Jan 
Published: February 2020

Abstract
Determination of density by using the density meter was superior to pycnometry and hydrometry in precision, accuracy, insensitivity to operator, temperature control, speed, and adaptability to automation. The linearity between oscillation period and density in the range of ethanol-water solutions is more than adequate. The method is practically insensitive to changes in air pressure; the single most important influence on the error in results is temperature reading errors. It is recommended that the Organisation Internationale de Métrologie Légale General Formula be used to correlate densities with alcoholic strength.
High Performance Liquid Chromatographic Determination and Clearance Time of Aflatoxin Residues in Swine Tissues
Authors: Miller Doris M , Wilson David M , Wyatt Roger D , Mckinney Jerry K , Crowell Wayne A , Stuart Barry P 
Published: February 2020

Abstract
Liver, kidney, and muscle tissues from swine given a single oral dose of 1.2 mg aflatoxins/kg body weight and from young pigs fed an aflatoxin-contaminated diet (0,400, or 800 ng/g feed) for 10 weeks were analyzed for aflatoxin residues. Extraction was performed according to the method of Stubblef ield and Shotwell. Aflatoxin residues were detected by high performance liquid chromatography (HPLC), and residue levels were correlated with withdrawal times. Residues were present in liver and kidney but not muscle by 12 h post-dosing; residues were detected in muscle after 24 h. Residue levels decreased over the 72 h period in all tissues. No aflatoxin residues were detected in the muscle from any pig 72 h postdosing or in those pigs fed the 400 ng/g diet, but were present in the muscle of pigs fed the 800 ng/g diet.
High Pressure Liquid Chromatographic Determination of Physostigmine Salicylate and Physostigmine Sulfate in Liquids and Ointments: Collaborative Study
Authors: Tymes Norlin W ,   Collaborators:, Briguglio G , Corcoran C , Everett R , Feyns L V , Fisher E , Gray V , Hughes D , Lazar A , Marks A , Radin J , Thompson R 
Published: February 2020

Abstract
Results of 11 laboratories are presented for the collaborative study of a proposed method for the quantitative reverse phase high pressure liquid chromatographic (HPLC) determination of physostigmine salicylate and physostigmine sulfate in pharmaceutical formulations. The samples consisted of commercial solution, injection, and ointment preparations, each containing one of the physostigmine salts. The physostigmine salt is extracted from ointments with acetonitrile after the ointment is dissolved in hexane. Liquid preparations are diluted directly. Physostigmine is determined at 254 nm on a C18 column by comparison with a physostigmine standard. Flurazepam hydrochloride is the internal standard. The method has been adopted official first action for the solution dosage form.
Evaluation of Analytical Methods Used for Regulation
Authors: Horwitz William 
Published: February 2020

Abstract
Regulatory analysis requires methods for analysis for 3purposes: surveillance, to detect problems; monitoring, to follow trends; and compliance, to enforce specifications (standards, action levels, tolerances). Each purpose requires a different weight to be assigned to the relative importance of the scientific characteristics of methods of analysis: systematic error, repeatability, reproducibility, limit of determination, and specificity. Evaluation consists of balancing the level of scientific requirements against the practical considerations of cost, time, and level of (raining required. In trace analysis, FDA utilizes recovery limits of 80-110% at ≥0.1 ppm and 60-100% below. The criterion for acceptable reproducibility (total of between- and within-laboratories) of methods of analysis can be represented by a relationship between coefficient of variation and concentration. The results of collaborative studies show that 10% outliers must be tolerated, but above 20% is excessive. Other new, important criteria for evaluation of methods at trace levels are % false positives, false negatives, and the magnitude of the blank.
Dry Ashing, Hydride Generation Atomic Absorption Spectrometric Determination of Arsenic and Selenium in Foods
Authors: Tam Gerard K H , Lacroix Gladys 
Published: February 2020

Abstract
A dry ashing, flameless atomic absorption spectrometric method was evaluated to determine arsenic and selenium in foods. Samples were dry-ashed with Mg(N03)2-MgO and dissolved in HC1. Selenate was reduced to selenite by boiling in 4N HC1, and arsenate to arsenite by treatment with KI. Hydrides of arsenic and selenium were generated by the addition of NaBH4 and were swept by nitrogen and hydrogen into a thermally heated silicate tube furnace. The detection limit was about 5 ppb for each element based on a 10 g sample. Analytical results obtained for several samples of NBS reference materials agreed with the certified values. The procedure was evaluated by another laboratory and results were satisfactory.
Evaluation of Thin Layer, Paper, and High Performance Liquid Chromatography for Identification of Dyes Extracted as Ion-Pairs with Tri-n-octylamine
Authors: Puttemans Marc L , Dryon Louis , Massart Désiré L 
Published: February 2020

Abstract
Food dyes, extracted into chloroform as ion-pairs with tri-n-octylamine, are chromatographed directly in various liquid chromatographic systems. Dyes can be identified by comparison of the chromatographic behavior of ion-pairs with behavior of reference dyes dissolved in water. In thin layer and paper chromatography, the ion-pairs dissociate when polar eluants are used; thin layer chromatography is preferred because of less tailing. In high performance liquid chromatography, a reverse phase ion-pair system is used with tetrabutylammonium as the counter ion; chloroform-extracted dyes show retention times similar to reference dyes dissolved in water.
Modification of the AOAC Gas-Liquid Chromatographic Method for Indole in Shrimp: Collaborative Study
Authors: Chambers Theodore L ,   Collaborators:, Netz E C , Ogger K 
Published: February 2020

Abstract
Several changes were suggested for standardization of the AOAC official final action gas chromatographic method for the determination of indole in shrimp. In a collaborative study, 3 FDA laboratories compared the modified method with the current method. At a 95% confidence level, the same results were obtained for each respective sample by the AOAC or the modified method, which had the following changes. The cleanup column was standardized by drying the silica gel for 2 h at 125°C and equilibrating with 3 g of water/25 g of silica gel. Concentrated ethyl acetate shrimp extracts were treated with anhydrous sodium sulfate before column cleanup and indole was eluted from the column with 15% ethyl ether/hexane. A reduced amount of the internal standard, 2-methylindole, was used to improve peak height measurements at the 25 μg% indole level. The modified method has been adopted official first action to replace method 18.075.
Determination of Background Levels of Lead and Cadmium in Raw Agricultural Crops by Using Differential Pulse Anodic Stripping Voltammetry
Authors: Satzger R Duane , Clow Charles S , Bonnin Evelyn , Fricke Fred L 
Published: February 2020

Abstract
A method is described for the simultaneous determination of ultratrace levels of lead and cadmium in selected agricultural crop samples by differential pulse anodic stripping voltammetry. Samples are dry ashed at high temperature with H2SO4 as an ashing aid. Techniques are described to control the lead and cadmium blank levels of 2 ng and 0.4 ng, respectively. Typical relative standard deviations for the crop analyses are 13% at 100 ng/g and 25% at 10 ng/g for lead, and 5% at 100 ng/g and 10% at 10 ng/g for cadmium. The lowest quantifiable level, based on 3 g dry sample, is 2 ng/g for lead and 1 ng/g for cadmium. Recovery studies, precision studies, and analyses of NBS Standard Reference Materials demonstrate the accuracy and reproducibility of this technique. A summary of results for over 1700 crop samples is reported.
High Performance Liquid Chromatographic Determination of Difenzoquat Residues in Water
Authors: Ahmad Ijaz 
Published: February 2020

Abstract
A simple analytical method is described for the quantitative determination of difenzoquat (1,2- dimethyl-3,5-diphenyl-lH-pyrazolium methyl sulfate) residues in water. The method involves high performance liquid chromatography with ultraviolet detection at 255 nm. The procedure is used to determine 2 ppb to 1 ppm levels of difenzoquat in pure and tap water. Samples which contain ≥50 ppb difenzoquat are injected directly into the liquid chromatograph without prior separation, concentration, or purification. Samples containing ≤50 ppb difenzoquat are first enriched on C18 Sep-Pak reverse phase cartridges and then injected into the liquid chromatograph. Average recoveries of difenzoquat were greater than 92% with a coefficient of variation less than 4.5%. The method can be used for water samples with difenzoquat concentrations as low as 2 ppb.
High Performance Liquid Chromatographic Determination of Caffeine in Decaffeinated Coffee, Tea, and Beverage Products
Authors: Ashoor Samy H , Seperich George J , Monte Woodrow C , Welty Jim 
Published: February 2020

Abstract
A method was developed for determining caffeine in decaffeinated coffee, tea, and beverage products by high performance liquid chromatography (HPLC). The HPLC system consisted of a Bio-Sil ODS-5S C18 column, methanol-water (25 + 75) mobile phase at 1 mL/min, and a UV detector. The method is simple and specific. Caffeine recoveries were 93.8-98.3% and coefficients of variation were 0.90-2.25%.
High Performance Liquid Chromatographic Determination of Seven Antioxidants in Oil and Lard: Collaborative Study
Authors: Page B Denis ,   Collaborators:, Bigornia R , Blanc M , Charbonneau C , Lamontagne J-C , Minnee J S , Perfetti G , Wong L , Zorniak D 
Published: February 2020

Abstract
A high performance liquid chromatographic procedure for the determination of propyl gallate (PG), 2,4,5-trihydroxybutyrophenone (THBP), tert-butylhydroquinone (TBHQ), nordihydroguaiaretic acid (NDGA), 2- and 3-tert-buty1-4-hydroxyanisole (BHA), 2,6-di-tert-buty1-4-hydroxymethylphenol (Ionox-100), and 3,5-di-tert-buty1-4-hydroxytoluene (BHT) was collaboratively studied by 8 laboratories. The 14 samples analyzed consisted of 10 vegetable oil samples spiked in matched pairs at about 200,100, and 20ppm and 4 lard samples spiked in matched pairs at about 100 and 40 ppm for each antioxidant except NDGA which was spiked only at the 2 lower levels in oil. In the method studied, the samples were dissolved in hexane and the antioxidants were partitioned into acetonitrile. The acetonitrile was concentrated and diluted with isopropanol to give isopropanol-acetonitrile (1 + 1). The antioxidants were separated by reverse phase gradient elution and detected at 280 nm. The results from one laboratory were rejected as outlying and were not considered in any calculations. For the remaining 7 laboratories, the overall mean recoveries for PG, THBP, TBHQ, NDGA, BHA, Ionox-100, and BHT were 93.2, 95.1,95.6,95.5,98.3,95.8, and 84.8%, respectively, and the overall mean coefficients of variation were 5.02,7.74, 19.3,4.36,3.75,6.33, and 3.45%, respectively.
High Pressure Liquid Chromatographic Determination of Nitrogen Derived from Urea and Water-Soluble Methylene Ureas in Urea Formaldehyde Fertilizers: Collaborative Study
Authors: Davidson Allan D ,   Collaborators:, Austin E R , Christensen B M , Coggin D , Diuguid J , Francis H K , Johnson F J , Porterfield D G , Proksa P , Quick F E , Reese B , Teague R T 
Published: February 2020

Abstract
A melhod for measuring nitrogen derived from urea, melhylenediurea (MDU), and dimethylenetriurea (DMTU) was tested by 9 collaborators. Collaborators made single determinations on 2 separate days on 5 sets of paired samples. Samples were extracted with water, filtered, and analyzed after high pressure liquid chromatographic separation on a C-8 or C-18 bonded silica column, using a refractive index detector. Peak heights compared to external standard of each component were used for quantitation. Mean coefficients of variation for the completed study were 3.24% for urea, 3.48% for MDU, and 6.56% for DMTU. The method has been adopted official first action.
High Pressure Liquid Chromatographic Determination of Oxazepam Dosage Forms: Collaborative Study
Authors: Bargo Eileen S ,   Collaborators:, Aranda E , Bonnin C , Hauser S , Henry K , Murphy C , Newman A , Perry J , Reed G , Rutgers J , Williams P 
Published: February 2020

Abstract
A reverse phase high pressure liquid chromatographic method for the determination of oxazepam in tablets and capsules was collaboratively studied by 9 laboratories. Collaborators were supplied with 6 samples that included synthetic and commercial formulations. Tablet and capsule composites are diluted with methanol and filtered. Oxazepam is determined at 254 nm by using a C18 column. Mean recoveries of oxazepam from synthetic tablet and capsule formulations were 97.2 and 99.0%, respectively. Mean coefficients of variation for tablets and capsules ranged from 1.85 to 2.86%. The method has been adopted official first action.
Enumeration of Coliforms in Nonfat Dry Milk and Canned Custard by Hydrophobic Grid Membrane Filter Method: Collaborative Study
Authors: Entis Phyllis ,   Collaborators:, Ciebin B W , Gipson V , Grahn M , Hunt S , Idziak E , Kalinowski R J , Kreiger F , Lachapelle G , Lancette G A , Lanier J M , Lister M M , Martin A , Maserang D L , Nath E J , Oji R T , Plank W M , Ponycharierks D , Smith A M , Varney G W , Wong P , Zapatka F A 
Published: February 2020

Abstract
A collaborative study was conducted in 14 laboratories to evaluate the performance of the hydrophobic grid membrane filter method against the official final action method, 46.016, for enumeration of colif orms in foods. Twelve artificially contaminated samples of nonfat dry milk and canned custard were analyzed by each laboratory. The random errors (Sr2) associated with the hydrophobic grid membrane filter method were significantly lower than those of the official method, and the counts obtained by the new method fell within the 95% confidence interval of the reference method. The colif orm counts obtained by tiie hydrophobic grid membrane filter method did not differ significantly from those obtained by the reference method as measured by a 3-way analysis of variance. The new method has been adopted official first action.