bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infrared Studies of the Dynamic Aspects of Hydrogen-Bonding in Hydroxylated Metabolites of 2,5,2′,5′,-Tetrachlorobiphenyl
Authors: Chen Jo-Yun T 
Published: February 2020

Abstract
Infrared spectral studies indicate that the hydroxylated 2,5,2′,5′-tetrachlorobiphenyls (TCBs) exist in a dynamic equilibrium of free, intramolecular, and intermolecular hydrogen-bonded forms. The relative abundances of the various species depend upon the polarity of the solvents as well as the physical state of the compound resulting from different configurations, i.e., the monohydroxylated 2,5,2′,5′-TCBs exist as cis and trans rotational isomers of OH with respect to the chlorine atom in the ortho position, and 3,4-dihydro-3,4-dihydroxy-2,5,2′,5′-TCB exists as 2 trans conformers with the OH groups either axial-axial or equatorial-equatorial with respect to the plane of the attached ring. In the solid state, the dimer or polymer is preferred with intermolecular hydrogen-bonding occurring between OH groups.
Rapid Thin Layer Chromatographic Method for the Detection of Histamine in Fish Products
Authors: Schutz David E , Chang George W , Bjeldanes Leonard F 
Published: February 2020

Abstract
A rapid, convenient thin layer chromatographic (TLC) method for detecting histamine in fish samples is described. Samples of press juice or fish flesh are applied directly to TLC plates. The plates are developed with acetone-ammonium hydroxide (95+5) and the spots are visualized with ninhydrin or Pauly’s reagent. Chromatographic separation of histamine from other fish components is readily achieved by this method.
A Simplified Method for the Gas-Liquid Chromatographic Determination of Methyl Mercury in Fish and Shellfish
Authors: Watts James O , Boyer Kenneth W , Cortez Anthony , Elkins Edgar R 
Published: February 2020

Abstract
A simple acetone wash of the fish sample which removes lipids and other organic materials replaces the cysteine cleanup specified in other methods. Methyl mercury is freed by hydrochloric acid, extracted into benzene, and determined with a gas-liquid chromatograph equipped with an electron capture detector. The method is quantitative for methyl mercury levels as low as 0.10 ppm in fish and shellfish. Ethyl mercury chloride may be used as an internal standard to detect unsuspected error or instrumental parameter variation.
A Simple Spectrophotometric Method for the Determination of Carbofuran Residues
Authors: Rangaswamy Jois R , VijayaShankar Yadathora N , Prakash Shimoga R 
Published: February 2020

Abstract
A method has been developed for carbofuran residues, based on coupling carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methyl carbamate) with diazotized aniline to form a yellow compound with an absorption maximum at 460 nm. The relationship between absorbance and concentration is linear for 1–10 μg carbofuran/5 ml. The method is sensitive and can be applied to the determination of levels as low as 0.025 ppm carbofuran in a 40 g crop or soil sample.
Identification of Human Seminal Acid Phosphatase by Electrophoresis
Authors: Stolorow Mark D , Hauncher James D , Stuver Willard C 
Published: February 2020

Abstract
Recent advances in forensic science in the identification of human seminal acid phosphatase are presented, with particular attention to the acrylamide gel electrophoretic method. In that method a difficulty in distinguishing seminal acid phosphatase from certain fecal phosphatases has been observed and an attempt is made here to distinguish the phosphatases from one another experimentally by differential substrate specificity. 4-Methylumbelliferyl phosphate and α-naphthyl acid phosphate are used as reaction substrates. Although seminal and vaginal acid phosphatases are differentiated by the modified method, fecal phosphatase is not clearly differentiated from seminal acid phosphatase.
Systematic Approach to the Detection of Explosive Residues. IV. Military Explosives
Authors: Midkiff Charles R , Washington Willard D 
Published: February 2020

Abstract
Part IV of the series encompasses tests for the detection and identification of military explosives collected at the scene of a criminal bombing. Major categories and typical formulations of some common military explosives are described. Tests are described and evaluated for the identification of 2,4,6-trinitrotoluene, cyclotrimethylenetrinitramine, and pentaerythritol tetranitrate. Thin layer chromatography and infrared spectroscopy are used for the identification of major explosive components. Tests for minor components to enable characterization and to distinguish similar compositions are included.
Confirmation of Results of Rapid Screening Test for Aflatoxins Performed at Corn Elevator
Authors: Shotwell Odette L , Shannon Gail M , Goulden Marion L 
Published: February 2020

Abstract
A screening method for corn and corn products, based on a minicolumn, was modified slightly to assay 60 lots of corn at one elevator to determine whether they could be sold as animal feed. To be salable, the lots had to contain less than 20 ppb total aflatoxin. Aflatoxin levels in the lots were later determined by the official AOAC method for corn to check effectiveness of the screening. No lot had been designated for sale that contained 20 or more ppb total aflatoxin.
Stability of Patulin to Sulfur Dioxide and to Yeast Fermentation
Authors: Burroughs Leonard F 
Published: February 2020

Abstract
The affinity of patulin for sulfur dioxide (SO2) is much less than was previously reported and is of little significance at the SO2 concentrations (below 200 ppm) used in the processing of apple juice and cider. However, at concentrations of 2000 ppm SO2 and 15 ppm patulin, combination was 90% complete in 2 days. Removal of SO2 liberated only part of the patulin, which suggests that 2 mechanisms are involved: one reversible (opening the hemiacetal ring) and one irreversible (SO2 addition at the double bond). Tests with 2 yeasts used in English commercial cider making confirmed that patulin is effectively removed during yeast fermentation.
Mass Spectral Confirmation of Aflatoxins
Authors: Haddon William F , Masri M Sid , Randall V Garcia , Elsken Richard H , Meneghelli Barry J 
Published: February 2020

Abstract
Two methods for mass spectral (MS) confirmation of aflatoxins in agricultural products and in physiological fluids are described. In the first method, electron ionization (EI) mass spectra are obtained following isolation by thin layer chromatography (TLC) and compared with available reference mass spectra to provide structural confirmation. Extensive sample cleanup is required for confirmation at the 10—1000 ppb level and minimum sample size is 10—50 ng aflatoxin isolated by TLC. The second method restricts the MS scanning to particular ions which are characteristic of the suspected aflatoxins and requires spectrometer resolution above 5000. The latter method, called high resolution selected ion monitoring (HRSIM), has a sensitivity below 0.0001 μg for aflatoxin B1 and makes possible direct analysis of complex mixtures. Employing HRSIM analysis on complex mixtures lowers the detection limit for aflatoxins M1 and B1 by 100-fold or more below the limit for highly purified samples. We attribute this dramatic sensitivity enhancement to a reduction in surface bonding between the aflatoxins and the glass sample containers used to introduce the samples. The HRSIM is generally applicable to compounds that cannot be separated by gas chromatography prior to MS analysis.
High Performance Liquid Chromatographic Determination of Provitamin A in Orange Juice
Authors: Stewart Ivan 
Published: February 2020

Abstract
A quantitative method has been developed for the determination of α- and β-carotenes and β-cryptoxanthin, the provitamin A carotenoids in orange juice. The carotenoids were separated by high performance liquid chromatography on a single column in approximately 30 min. The procedure may also be used to measure zeta-carotene and α-cryptoxanthin.
Practical Considerations in the Use of High Performance Liquid Chromatographic Columns
Authors: Majors Ronald E 
Published: February 2020

Abstract
The practical aspects of high performance liquid chromatographic (HPLC) column preparation and operation are reviewed. Recent advances in columns are briefly covered. Porous layer beads and the new microparticles are compared. The design of HPLC columns with respect to optimum dimensions in analytical and preparative techniques and the materials used for column construction are detailed. The effects on column performance of extra-column volumes (i.e., connecting tubing and fittings) and injection procedures and techniques are pointed out. Procedures for preparing the column, including slurry packing techniques for microparticles, are given. The influence of solvent purity in isocratic and gradient elution in column operation and practical techniques for removing impurities are presented. Solvents and buffers useful for operation in the far ultraviolet region (190—210 nm) are tabulated, and a practical example of the use of this wavelength region for the detection of carbohydrates is presented. The practical aspects of liquid-solid chromatography (LSC) including activity and retention time reproducibility are discussed. Difficulties encountered in LSC are listed and suggestions are made to solve them. The advantages and disadvantages of the new chemically bonded phase packings are covered. Details of a new technique, ion-pair partition chromatography, are presented along with suggested applications.
Identification of Hexachlorobenzene as a Contaminant in Laboratory Plastic Wash Bottles
Authors: Rourke David R , Mueller Wolfgang F , Yang Raymond S H 
Published: February 2020

Abstract
Hexachlorobenzene (HCB) is identified as a contaminant in some Nalgene plastic wash bottles by gas-liquid chromatography-mass spectrometry. Of 34 new, unused Nalgene bottles tested, all 30 of the conventional polyethylene wash bottles contained significant quantities of HCB; the remaining 2 linear polyethylene and 2 polyvinyl chloride storage bottles contained little or no HCB.
Gas-Liquid Chromatographic Determination of Butylated Hydroxyanisole and Butylated Hydroxytoluene in Edible Oils
Authors: Senten Jozef R , Waumans Jozef M , Clement Jean M 
Published: February 2020

Abstract
A method is described for the quantitative determination of butylated hydroxyanisole and butylated hydroxytoluene in edible oils. Both antioxidants are extracted with acetonitrile, and quantitated by gas-liquid chromatography, using a hydrogen flame ionization detection system and di-tert-butyl-4-hydroxyanisole as an internal standard. The standard addition technique is used. Recoveries from oils containing 70–400 ppm by weight of both antioxidants ranged from 88 to 104%.
Survey of Finfish and Shellfish for Volatile N-Nitrosamines
Authors: Havery Donald C , Fazio Thomas 
Published: February 2020

Abstract
A variety of finfish and shellfish obtained on the local retail market were analyzed for 14 volatile N-nitrosamines by using a gas-liquid chromatographic method demonstrated to be sensitive to 10 ppb (μg/kg). A total of 78 samples (fresh, frozen, and canned), representing 26 varieties of fish, were analyzed. No nitrosamines were found.
Method for the Flotation Oil Extraction of Light Filth from Ground Capsicums
Authors: Thrasher Joel J , Colliflower Emma Jean 
Published: February 2020

Abstract
The present official first action method for ground capsicums, 44.123, was adopted in 1945 and there have been great changes in processing and examination of spices since that time. The proposed method involves isopropanol pretreatment, followed by wet sieving and extraction of the light filth from 60% ethanol with flotation oil. The filter papers were clean and recoveries were good (95%) for 5 different lots of capsicums and annato spiked with insect fragments and rodent hairs.
New Colorimetric Method for Folic Acid Assay in Dosage Forms
Authors: Ramana Rao Griddaluru , Mahajan Surinder N , Kanjilal Geeta , Mohan Katta R 
Published: February 2020

Abstract
A new colorimetric method has been developed for estimating folic acid. The British Pharmacopoeial method has been modified to reduce folic acid to 2,4,5-triamino-6-hydroxypyrimidine (TAHP), which is treated with nin-hydrin to yield a stable purple complex. Participation of 5-amino and 6-hydroxy groups of TAHP in the color reaction with ninhydrin is suggested on the basis of experimental evidence. The color obtained has an absorbance maximum at 555 nm and obeys Beer’s law in the concentration range of 4.5 to 45 μg folic acid/ml. The method has been successfully used for assaying folic acid, its tablets, and injections.
Fluorometric Determination of Glycerol in Wine—Comparison with Other Known Procedures
Authors: Avellini Paolo , Damiani Pietro , Burini Giovanni 
Published: February 2020

Abstract
The glycerol content of 6 wines was evaluated by using 3 different preliminary treatments and, subsequently, a variety of instrumental and chemical procedures (fluorometric, vapor phase chromatography of trimethylsilyl derivatives, volumetric, and colorimetric). The data showed that all these procedures are applicable; in particular, the fluorometric procedure, which has not been used until now, provides average recoveries of added glycerol ranging from 99.3 to 100.9%, with relative standard deviations ranging from 2.9 to 3.2%. Vapor phase chromatography provides average recoveries of added glycerol ranging from 99.8 to 100.1%, with relative standard deviations ranging from 1.0 to 2.7%. Therefore, the fluorometric procedure appears especially useful for reliable routine analyses, because it is specific for glycerol and provides results that are unaffected by preliminary treatment. Thus it allows analysis of diluted wine, when the sugar content does not exceed 5 g/L; sweet wines must undergo an ion exchange pretreatment.
Spectroscopic and Chromatographic Identification of Dimethylamphetamines
Authors: Bailey Keith , Gagné Denise R , Legault Donald , Pike Richard K 
Published: February 2020

Abstract
The qualitative analysis of the 6 isomeric dimethylamphetamines (both methyl groups on the aromatic ring) is described. Their ultraviolet, mass, and proton magnetic resonance spectra are similar, but infrared spectra allow a positive identification to be made, and reference spectra are provided. Melting point and gas-liquid and thin layer chromatographic data are also presented.
Specific Determination of Sucrose in Honey
Authors: White Jonathan W 
Published: February 2020

Abstract
This paper describes a procedure for determining sucrose in honey without its preliminary separation. Interference from the large excess of glucose is removed by treating with glucose oxidase-catalase, and then the glucose from invertase hydrolysis of sucrose is measured. Sucrose is difficult to measure in honey because of its low concentration and the presence of at least 24 other sugars. Standard deviation between duplicates for 50 honey samples containing from 0.06 to 10.6% sucrose was 0.19; no known honey sugars interfered. The selective adsorption method for separating sucrose from interfering oligosaccharides is too slow for repetitive analysis of honey for sucrose only, although it is 8 times more sensitive than the procedure described. Results of analysis of 13 honey samples for sucrose by this procedure (averaging 1.66%) and the selective adsorption method (averaging 1.59%) did not differ significantly.
Separation and Analysis of the Pyrethrins by Combined Gas-Liquid Chromatography-Chemical Ionization Mass Spectrometry
Authors: Holmstead Roy L , Soderlund David M 
Published: February 2020

Abstract
Pyrethrins, the 6 naturally occurring insecticidal esters of pyrethrum extract, were analyzed by combined gas-liquid chromatography-chemical ionization mass spectrometry. Separation was best on an OV-25 column with temperature programming. The chemical ionization mass spectra for the 6 esters as well as for the thermally isomerized pyrethrins I and II are reported and discussed. Using selective ion monitoring, a lower limit of detectability of all 6 esters was 114 ng of total extract injected on the column.
Determination of Free Urea in Fertilizers Containing Urea Formaldehyde Polymers
Authors: Barbera Andrea , Canepa Diego 
Published: February 2020

Abstract
This report describes a method for determining free, unreacted urea nitrogen in mixed compounds containing condensation products of urea and formaldehyde by using an ammonia gas-sensing electrode. Free urea is determined by potentiometrically measuring the ammonia produced following exhaustive hydrolysis by urease and subtracting the amount of ammonia present before enzymatic hydrolysis. Urea of condensed polymers does not interfere in free urea determination.
Collaborative Study of High Pressure Liquid Chromatographic Method for Determining Methyl Parathion
Authors: Jackson Edwin R 
Published: February 2020

Abstract
Methyl parathion in technical material, 4 lb/gal. emulsifiable concentrate, and 6 lb toxaphene-3 lb methyl parathion/gal. emulsifiable concentrate was chromatographed on microparticulate silica with 40% water-saturated chloroform mobile phase and 254 nm ultraviolet detection. Ten collaborators reported results on 3 matched pairs of samples by peak height measurements with acetophenone as internal standard. The mean of the coefficients of variation for the 6 samples was 1.71%. Results for 4 of the samples were compared with gas-liquid chromatographic results on the same samples. No difference in the means by the 2 methods was noted at the 95% confidence level. The method has been adopted as official first action.
Reverse Phase High Pressure Liquid Chromatography of Vitamin A in Margarine, Infant Formula, and Fortified Milk
Authors: Thompson James N , Maxwell William B 
Published: February 2020

Abstract
Retinol was determined in margarine (50 mg), infant formula (1 ml), and fortified milk (1 ml) by saponification in centrifuge tubes, extraction of the unsaponifiable lipid with hexane, and high pressure liquid chromatography (HPLC) in 90% methanol on a 25 cm × 3.2 mm column containing 10 μm LiChrosorb reverse phase. β-Carotene was determined using the same column and 99% methanol as eluant. The vitamins in the eluate were identified and measured from their absorption at 325 (retinol) and 453 nm (β-carotene), using a computing integrator. Retinol and carotene were prominent peaks in the chromatograms from properly fortified samples and were satisfactorily separated from other materials. In a survey of 12 different margarines for retinol, the results from liquid chromatography agreed with those of a variety of Spectrophotometric and fluorometric procedures but they were obtained with greater ease and they could be interpreted more confidently. The recovery of retinol from oil was better than 99%. The coefficients of variation were 6.8% for 12 replicate analyses of a margarine for retinol and 5.4% for 10 replicate analyses of a margarine for β-carotene.
Argon Plasma Emission Spectroscopic Determination of Boron in Fertilizers
Authors: Melton James R , Hoover William L , Morris Patricia A 
Published: February 2020

Abstract
An atomic emission spectroscopic method is described for the rapid, precise, and accurate determination of boron in fertilizers at levels ≥0.002%. Acid-soluble boron is determined by argon plasma emission spectroscopy at 2497. 73Å. Lithium is added to mask enhancement of emissions by other alkali metals.
Comparison of Iodometric Titration, Potentiometric Titration, and Bromide Ion Electrode Determination for Bromide in Brominated Vegetable Oils
Authors: Conacher Henry B S , McKenzie Arthur D 
Published: February 2020

Abstract
Iodometric titration, potentiometric titration, and bromide selective ion electrode techniques have been evaluated for determining bromide in brominated vegetable oils. In general, the 2 titration methods gave similar percentages for the bromide content of several brominated vegetable oils, and similar recoveries of approximately 96% from soft drinks. The specific ion technique gave lower and more variable percentages for the bromide content of the brominated vegetable oils and a lower recovery of 91.6% from soft drinks. Of the first 2 methods, the potentiometric method was selected because of ease and speed of measurement.
Collaborative Study of Gas-Liquid Chromatographic Determination of Methaqualone in Pharmaceutical and Clandestine Preparations
Authors: Hanel Harold F 
Published: February 2020

Abstract
Eight laboratories collaboratively studied a procedure for the quantitative determination of methaqualone. HCl in pharmaceutical and clandestine preparations. Methaqualone is extracted from an aqueous bicarbonate solution into chloroform and quantitated by gas-liquid chromatography on a 3% OV-1 column. Tetraphenylethylene is used as an internal standard. Two commercial preparations and 4 sample mixtures prepared by the author were studied. Recoveries for the 4 prepared samples ranged from 100.0 to 102.6%, and the coefficients of variation ranged from 1.58 to 4.15% for the 6 samples studied. The method has been adopted as official first action.
Gas-Liquid Chromatographic Determination of Residues of Methane sulfonate of m-Aminobenzoic Acid Ethyl Ester in Fish
Authors: Sills Joe B , Luhning Charles W 
Published: February 2020

Abstract
In this gas-liquid chromatographic procedure for determining residues of methanesulfonate of m-aminobenzoic acid ethyl ester (MS-222) in fish muscle, homogenized tissue is extracted with distilled water, and proteins are removed by coagulation with trichloroacetic acid, centrifugation, and filtration. After careful pH adjustment of the filtrate, MS-222 is partitioned into benzene-ethyl ether and measured by alkali flame ionization gas chromatography. Tissues with known additions of 1–19 μg MS-222/ g were analyzed, with recoveries of 84–95%.
Simple Sensitive Technique for Detecting Organochlorine Pesticides on Thin Layer Chromatograms
Authors: Ludwick Adriane G , Lau Aldrich N K , Ludwick Larry M 
Published: February 2020

Abstract
Chlorinated hydrocarbon pesticides can be quickly detected using commercially available thin layer chromatographic plates dipped in an acetone solution of silver nitrate. The limits of detection are functions of the pesticide, adsorbent, developing system, and concentration of the silver nitrate in acetone solution. On exposure to ultraviolet light, 0.002 μg 2,4,5-T produced clear darkening within 30 min on precoated silica gel plates (polyvinyl alcohol binder) coated with a solution of 0.1% silver nitrate in acetone. For this system, a 60-min detection period was necessary for a 0.05% coating solution. On the silica gel plates (polyvinyl alcohol binder, 0.1% silver nitrate), 0.02 μg lindane is detected within 75 min. For alumina plates (polyvinyl alcohol binder, 0.1% silver nitrate), 0.025 μg aldrin is detected within 10 min. Darkening of this plate prohibits the detection of 0.012 μg aldrin. On silica gel plates (polyvinyl alcohol binder, 0.1% silver nitrate), 0.015 μg aldrin can be detected within 45 min. The method described provides sensitivities equal to or exceeding literature values.