bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Nitrite and Nitrate Determinations in Vegetables: Suitability for Accurate and Automated Measurements
Authors: Lox Frans , Okabe Akitsugu 
Published: February 2020

Abstract
A method is reported for improved accuracy for nitrate and nitrite determinations in aqueous solutions, especially plant extracts. The sampling procedure can be adapted for automated determinations: At least 6 aliquots with increasing volume of nitratecontaining solutions are subjected to the reducing agent under stabilized conditions to obtain nitrite, treated with one of 2 different diazotization reagents, and measured colorimetrically. The slope of the curve, absorbance vs sampled volume, is determined by linear regression; this slope is directly dependent on the nitrate (nitrite) content. Original nitrite is determined by omitting the reducing step. Low nitrate levels (&lt;0.1 μg/mL) can be determined directly with the sulfanilamide-N-(l-naphthyl)ethylenediamine dihydrochloride diazotization procedure or indirectly by constant nitrate addition, with the sulfanilic acid-1-naphthylamine hydrochloride diazotization mixture (Griess reagent). The latter procedure can be used to measure concentrations up to20μg/mL.
Wax in Wool by Wide-Line Proton Magnetic Resonance: Rapid Non-Destructive Method
Authors: O'Keefe John H , Sharry Leo F 
Published: February 2020

Abstract
A wide-line proton magnetic resonance technique (PMR), in which hydrogen response is used as the measure of wax in dried greasy wool, is a viable and preferred alternative to the commonly used Soxhlet procedure in which extracted weight is measured. The validity of the PMR method depends on wax hydrogen composition (inter- and intra-breed) being constant, and on background contribution from non-wax hydrogen (in suint, wool fiber, and vegetable matter) being small and constant. The experimentation reported in this paper shows that both requirements are met. The PMR method for wax is precise (better than 0.1% at mid-range); rapid (200 samples per 8 h day); sensitive (better than 15 mg); and yields a linear calibration graph over the entire range (0-100%) for a 5 g sample. A comparison of the methods shows that the linear regression line for wax by Soxhlet (y) against wax by PMR (x) is given by y = 1.0257 (SE 0.2277) + 0.9894 (SE 0.0142)x, with r2 = 0.99, and n = 20.
Colorimetric Determination of 3-Amino-l,2,4-Triazole in Grain or Meal
Authors: Galoux Michel , Van Damme Jean-C , Bernes Albert 
Published: February 2020

Abstract
This colorimetric method for the determination of 3-amino-l,2,4-triazole in grain or meal is a modification of the Storherr and Burke method. The herbicide is extracted from grain with methanol, and purified by adsorption-desorption on resin. The extract is cleaned by digestion with sulfuric acid and clarified with charcoal. The colored complex formed by coupling with N-(1-naphthyl)ethylenediammonium dichloride is measured spectrophotometrically at 455 nm. The limit of detection is 0.05 ppm.
Gas-Liquid Chromatographic Determination of Residues of Oxadiazon and Its Metabolites in Green and Dry Hops and Hop Foliage
Authors: George Donald A 
Published: February 2020

Abstract
Ronstar EC (emulsifiable concentrate) was applied at rates of 4.48 or 8.96 kg ai/ha as a broadcast spray during the winter, in late spring, and in mid-summer to plots in commercial hop fields. Residues of oxadiazon, the active ingredient, and its 4 metabolites (methoxy, alcohol, acid, and phenol) were determined at harvest (1 month after last treatment) in green and dry hops and in hop foliage, by using gas-liquid chromatography after column chromatographic cleanup. Drying the cone increased residues of oxadiazon, but resulted in loss of the methoxy and alcohol metabolites. Oxadiazon residues in hop foliage ranged from 0.058 to 0.163 ppm. Measurable amounts of metabolites were also found in the foliage.
Spectrophotometric Determination of Carbaryl in Grains
Authors: Appaiah Kalapanda M , Ramakrishna Rasamsetti , Subbarao Kadari R , Kapur Omprakash 
Published: February 2020

Abstract
A method has been developed for determining carbaryl (1-naphthyl N-methyl carbamate) in grains, based on hydrolysis of carbaryl with methanolic potassium hydroxide to 1-naphthol, reaction with 4-aminophenazone in the presence of alkaline oxidizing agent, and spectrophotometric measurement at the absorption maximum at 475 nm. The relationship between absorbance and concentration is linear in the range of 0.5-20 μg/mL. The method can be applied to levels as low as 0.3 ppm carbaryl in grains.
Colorimetric Determination of Patulin Produced by Penicillium patulum
Authors: Subramanian Thirugnana 
Published: February 2020

Abstract
A quantitative method has been developed for the determination of patulin, a mycotoxin produced by Penicillium patulum. The fungus was grown separately in well defined liquid minimal medium, and on rice and bread for 15 days. Patulin was extracted with ethyl ether and determined colorimetrically, using phenylhydrazine hydrochloride. Recovery of pure patulin added to bread and rice was also studied. The lower limit of detection was 1 μg/g.
Effect of Adsorption of Histamine to Glass Surfaces on Its Estimation
Authors: Murray John , McGill Alister S 
Published: February 2020

Abstract
Histamine is rapidly adsorbed on the surface of glass containers when stored in aqueous or 10% methanol solution at ambient or sub-zero temperatures. This effect can lead to marked errors in the determination of histamine. Addition of acid to the holding medium or storage in polyethylene containers eliminates this effect
Accuracy of Pesticide Reference Standard Solutions. Part I. Factors Affecting Organic Solvent Evaporation
Authors: Hodgson David W , Watts Randall R 
Published: February 2020

Abstract
A gravimetric experiment was undertaken to identify the factors affecting solvent evaporation from analytical reference standard solutions and to establish the magnitude of the resultant solvent evaporation. The evaporation of organic solvent from standard solutions is affected by: (1) solvent, (2) container type, (3) solution volume, and (4) storage temperature. Solvents with low vapor pressure-to-surface tension ratios have low evaporation rates. Screw-cap containers with precision-made caps and seals have the lowest evaporation rates. The use of large-volume standard solutions reduces the percent solvent loss. Storage at refrigerator or freezer temperatures can reduce evaporation rate by as much as a factor of 7.
Simultaneous Electron Capture Detection of Chlorpyrifos and 3,5,6-Trichloro-2-pyridinol Residues in Peach and Bahia Grass Field Samples Following Gel Permeation Cleanup
Authors: Guinivan Richard A , Thompson Neal P , Bardalaye Promode C 
Published: February 2020

Abstract
A recently published method involving the simultaneous extraction, gel permeation cleanup, and electron capture gas chromatographic detection of residues of the insecticide and acaricide chlorpyrifos and its principal metabolite 3,5,6-trichIoro-2-pyridinol is successfully applied to Lorsban-treated peach and Bahia grass samples. Previous quantitation of these compounds has required 2 separate analytical procedures. Multilevel temperature programming and manipulation of the gel permeation column effluent rate are the only adjustments of experimental parameters necessary to avoid large amounts of gas chromatographic interferences. Chromatographic peaks are more clearly defined and easier to integrate with the multilevel program than they are with 2-step or linear programs. This is one reason that recovery data are improved over those reported for the method as applied in the pea vine work. Residue analyses conducted on field-treated peaches and Bahia grass show the newly published procedure to be sensitive and effective.
Analytical Methods for Drugs in the Next Decade
Authors: Zarembo John E 
Published: February 2020

Abstract
Today’s research for new drug substances is moving toward molecules of much larger molecular weight and complexity than the small, modern drug molecules, e.g., polypeptides, interferon, slow-releasing substances, and blood and plasma components. The complexity of natural products derived from human or other animal bodies requires a new analytical chemistry. Simple tests for drug stability, dissolution, and bioavailability will no longer suffice to provide and ensure purity and structural identity of such drugs. During the next decade, the demands on analytical chemists will increase; more biological organic and physical chemistry will be required by analysts to perform their jobs. Criteria for purity will require even greater chromatographic involvement but this will have to be complemented by nuclear magnetic resonance and mass spectrometry. The demands made on AOAC to validate and approve methods to assay drugs and determine their purity will increase enormously in this next decade. The understanding of drug purity will take on a new meaning because of the complex nature of natural products. Stability indication will be significant only when chemical and biological tests can complement and define the active components and the impurities. AOAC will be required to play a major role in assuring the manufacturer and the public that their drugs are adequately tested, safe, and efficacious.
Glass Capillary Gas Chromatography for Sensitive, Accurate Polychlorinated Biphenyl Analysis
Authors: Bush Brian , Connor Steven , Snow John 
Published: February 2020

Abstract
A simple method is described for preparing Apiezon L-coated glass capillary columns for polychlorinated biphenyl (PCB) analysis. The mass represented by each of 72 chromatographic peaks separated on this column from a mixture of Aroclors 1221,1016,1254, and 1260 was determined; the mixture could then be used as a universally applicable calibration standard for analysis of environmentally modified polychlorinated biphenyl mixtures at the parts per billion (ng/g) level. Analytical sensitivity is &lt;10 ng/mL for total PCBs and &lt;0.1 ng/mL for individual PCB congeners.
High Performance Liquid Chromatographic Method for Determination of Temephos in Technical and Formulated Products: Collaborative Study
Authors: Miles James W , Mount Dwight L 
Published: February 2020

Abstract
An HPLC method for the determination of temephos in temephos technical and formulated products has been subjected to an international collaborative study with 14 laboratories participating. Samples were extracted with ethyl acetate and eluted on a silica gel column with ethyl acetate-hexane (1 + 9); p-nitrophenyl p-nitrobenzoate served as the internal standard. Collaborators were furnished samples of technical, 20 and 50% emulsifiable concentrates, 50% water-dispersible powder, and 1% sand granules. The coefficients of variation of the values obtained on the 5 samples were 1.21,2.02,1.26,1.89, and 9.90%, respectively. The method has been adopted official first action.
Detection of Invasiveness of Mammalian Cells by Escherichia coli: Collaborative Study
Authors: Mehlman Ira J , Romero Aida , Atkinson John C , Aulisio Calvin , Sanders Arvey C 
Published: February 2020

Abstract
In a collaborative study of 2 standard procedures (Procedure I, presented in J. Assoc. Off. Anal. Chem. 60, 546-562 (1977) and Procedure II in the Bacteriological Analytical Manual, 1978), 7 laboratories evaluated the invasive potential of Escherichia coli. Monolayers of HeLa cultures were infected with E. coli (infectivity ratio 100 bacteria/mammalian cell) suspended in 2 menstrua: heat-inactivated fetal bovine serum (Procedure I) and 0.2% bovine albumin Fraction V dissolved in Earle’s buffered salts (Procedure II). After uptake of the bacteria, intracellular growth, and differential staining, the percentages of HeLa cells containing a minimum of 5 bacteria were determined microscopically. All laboratories correctly identified invasiveness of E. coli by Procedure I; 5 of 6 laboratories recognized invasiveness by Procedure II. Although Procedure I was more reproducible than Procedure II, repeatability did not differ significantly. Procedure I was adopted official first action for presumptive recognition of invasiveness in E. coli.
High Pressure Liquid Chromatographic Determination of Aflatoxins by Using Radial Compression Separation
Authors: Shepherd Eric C , Phillips Timothy D , Heidelbaugh Norman D , Hayes A Wallace 
Published: February 2020

Abstract
A rapid method for the determination of aflatoxins was developed using high pressure liquid chromatography and a radial compression separation system. A standard solution of aflatoxins B1, B1, G1, G2, and M1 was analyzed at flow rates of 2.0 and 6.0 mL/min. Retention times, peak heights, and peak areas were reproducible over a 3-day period. Coefficients of variation for aflatoxin B1 at 2.0 and 6.0 mL/min were, respectively, 1.04 and 0.87% (retention time); 2.9 and 4.7% (peak height); and 8.2 and 4.7% (peak area). At 6.0 mL/min there was an approximate 25% loss in sensitivity but a greater than 50% reduction in retention time. Separation of all the aflatoxins was excellent using a dual flow rate of 2.0 mL/min with a change to 8.0 mL/min at 15 min post-injection. The applicability of the radial compression separation system for the rapid determination of aflatoxins in human tissues was also tested. Spiked samples of liver, serum, and urine showed good resolution of all aflatoxin peaks at the higher flow rates.
Caution on Nitric Acid Digestion of Organic Samples in Closed Systems
Authors: Borggaard Ole K , Willems Marta 
Published: February 2020

Abstract
There is a risk of explosion when organic samples are digested with nitric acid in a closed vessel at elevated temperatures for elemental analysis. Sample size and the size, material, and thickness of bomb walls should be carefully considered. Digestion in an open flask may be a safer alternative.
Defining a Lowest Level of Reliable Measurement for Lead in Foods
Authors: Capar Stephen G , Subjoc Cheryl A 
Published: February 2020

Abstract
Procedures are outlined for defining and demonstrating a lowest level of reliable measurement for Pb in foods. The method of analysis studied was a dry ash sample mineralization with quantitation by differential pulse anodic stripping voltammetry at a hanging mercury drop electrode. Past experience with analyses for Pb in foods indicated that the lowest measurement of Pb in foods was limited by the Pb contributed from the reagents, apparatus, and laboratory environment. The magnitude of contamination from these 3 sources was investigated. Once a specific source of contamination was identified, attempts were made to eliminate or minimize the amount of Pb it contributed to the analysis. After contamination was controlled to the degree our facilities would allow, low level Pb determinations were performed on infant formula.
Application of Gel Permeation Chromatography and Nonaqueous Reverse Phase Chromatography to High Performance Liquid Chromatographic Determination of Retinyl Palmitate and α-Tocopheryl Acetate in Infant Formulas
Authors: Landen William O 
Published: February 2020

Abstract
A high performance liquid chromatographic (HPLC) method was developed for determining retinyl palmitate and α-tocopheryl acetate in infant formulas. The lipid-soluble components were extracted from the aqueous phase by homogenizing in a solvent mixture of isopropanol and methylene chloride with magnesium sulfate added to remove water. The vitamins were fractionated from the lipid material by using high pressure gel permeation chromatography (HP-GPC) followed by quantitation using nonaqueous reverse phase (RP)-HPLC. Three μStyragel (lOOÅ) columns connected in series were used for HP-GPC fractionation of sample extracts in methylene chloride. A Zorbax ODS (6 μm) column and methylene chloride-acetonitrile-methanol (30 + 70 + 0.2) were used for RP-HPLC quantitation. The 32 commercial infant formulas that were analyzed represent a wide variety of formulations manufactured at various fortification levels. Vitamin A results ranged from 89 to 242% of the declared levels. Vitamin E values, determined as the supplemental form a-tocopheryl acetate, ranged from 83 to 272% of the' declared levels. Determination of vitamin A in 6 samples and vitamin E in one sample by this method and the official AOAC method gave comparable results. This method, which requires no saponification, was successfully used to determine vitamins A and E in ready-to-use, liquid concentrated, and powdered infant formulas.
Gas Chromatographic Determination of Propionates as Paranitrobenzyl Ester in Bakery Products
Authors: Takatsuki Keigo , Sakai Keiichi 
Published: February 2020

Abstract
A procedure was developed to determine propionates used as mold inhibitors and preservatives in bakery products. Propionates were extracted from the sample with water alkalinized by potassium carbonate. Water was evaporated, and the residue was reacted with paranitrobenzyl bromide in dimethylformamide- water (90 + 10) at room temperature to convert propionates to paranitrobenzyl ester, which was determined with a gas chromatograph equipped with a flame ionization detector. Bakery products, such as bread, sponge cake, cookies, and biscuits, were analyzed by this procedure. Recoveries from samples fortified with propionates ranged from 94 to 101%, with a standard deviation of 3.32. The concentrations determined were 50 to 2500 μg/g sample.
Extract for Stable Isotope Ratio Isolation of Vanillin from Vanilla Analysis: Interlaboratory Study
Authors: Guarino Philip A 
Published: February 2020

Abstract
The Technical Committee of the Flavor and Extract Manufacturers' Association collaboratively tested 3 methods for isolation of vanillin from vanilla extract. Each of the 3 methods provided vanillin which was useful for the intended purpose, although 2 of the selected methods were preferred by the collaborators. The vanillin isolated by each of the 3 methods was suitable for stable isotope ratio analysis to determine whether the vanillin was of natural origin or had been added to the extract.
Verification of Authenticity of Apple Juice
Authors: Brause Allan R , Raterman Joseph M 
Published: February 2020

Abstract
A series of instrumental analyses is described for verification of apple juice authenticity. Liquid chromatography is used to determine sugars and individual phenolics, atomic absorption spectroscopy is used to determine potassium, standard AOAC methods are used to test for polyphenolics arid formol indexes, and stable carbon isotope ratio analysis (SCIRA) is used to detect high fructose corn syrup. These tests will identify fraudulent but not poorly processed apple juice.
Composite Sampling in the Determination of Pyrethrins in Fruit Samples
Authors: Ryan John Joseph , Pilon Jean-Claude , Leduc Raymonde 
Published: February 2020

Abstract
A residue method is described for measuring up to 6 naturally occurring pyrethrins in several varieties of fruits. Fresh samples are extracted into acetone, partitioned between water and hexane-dichloromethane, and cleaned up by adsorption on a Florisil column followed by elution with acetone-hexane (15 + 85). Residues are detected and quantitated by gas chromatography with electron capture detection. Detection limits for single 10 g samples are about 10-30 ng/g. The method was applied to a survey of pyrethrins in fruit samples. Because of the high tolerance (1 ppm) allowed for pyrethrins, the expected low incidence, and the low detection limits of the method, composite samples (up to 5-6) of fruit were used to quickly determine residue levels. This procedure allowed 130 samples to be processed in the time normally needed for 30-40. Provided the above conditions can be met, composite sampling is proposed as an attractive approach to data gathering in pesticide residue analysis.
Field Screening Method for Above-Tolerance Residues of Dithiocarbamate Fungicides
Authors: Ott Daniel E , Gunther Francis A 
Published: February 2020

Abstract
A field screening method has been developed for detecting above-tolerance residues of dithiocarbamate (DTC) fungicides on fruits and vegetables. A harvested crop might be condemned as unfit for market if above-tolerance DTC residues are present; however, by using this screening method, a grower might be able to postpone harvesting a crop until the screening test indicates that residues have dissipated below the tolerance level. The method depends on carbon disulfide generated from DTC fungicides at an elevated temperature into the headspace gas above the contents of a septum-sealed reaction flask, with hydrochloric acid and stannous chloride present. The syringe-withdrawn, headspace carbon disulfide then reacts with the appropriate chromophore reagent already in the syringe. The lower limit of detectability is about 2 ppm DTC fungicide from 30 g chopped crop. A single test can be completed in about 90 min; the average time per test when several are conducted sequentially is considerably shorter.
Toxicology of Lead: Primer for Analytical Chemists
Authors: Biddle Garfield N 
Published: February 2020

Abstract
Through the years, considerable amounts of Pb have been mobilized into our environment, and Pb may represent one of the most ubiquitous of all toxic metal contaminants. Excluding occupational exposure, the general population receives almost 70% of its total exposure to Pb from food. Other important sources of exposure include drinking water and air; minor sources include tobacco products, decorative glassware, and other types of food utensils. For young children, ingestion of Pb-containing soil or dust via normal hand-to-mouth activity or, in extreme cases, pica (the abnormal intake of soil, paint chips, etc.) may represent a significant source of exposure. The severity of clinical manifestations of Pb toxicity depends on both duration and intensity of exposure. Infants and young children are more susceptible to the effects of Pb than are adults. Although there is little debate over the serious consequences of acute, high-level Pb exposure, both controversy and concern have been expressed about the degree of risk that may be associated with chronic exposure to Pb levels that are closer to contemporary levels in the general environment. This concern is particularly high with regard to infants and young children, who may undergo Pb-induced changes that have long-term neurological impact (e.g., learning deficits, gross and/or fine motor dysfunction, impaired cognitive abilities).
The Analytical Blank: Sources and Effects on Lead Analyses
Authors: Skogerboe Rodney K 
Published: February 2020

Abstract
The influence of the analytical blank on the reliability of an analysis is often of paramount importance. It is shown that the magnitude of the blank and the degree of uncertainty associated with it usually limits the ability to complete quantitative analyses at lower concentration levels. Specific sources of lead contamination are discussed and data are presented that indicate the possible contributions from each source. Although exceptions surely occur, it appears that lead contributions from the laboratory environment and/or ancillary analytical equipment and materials are often the primary factor in determining the blank level and the variability therein.