bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas-Liquid Chromatographic Determination of Chloroform in Toothpastes, Using the Headspace Analytical Technique
Authors: Stutsman Martin J 
Published: February 2020

Abstract
Chloroform in toothpastes is determined by gas-liquid chromatography of the vapors in the headspace over a diluted sample, using an electron capture detector. The method is sensitive to small amounts of chloroform and avoids the injection of materials deleterious to the column. The 12' × 1/8" od stainless steel column is packed with acid-washed Gas-Chrom R coated with 2 0% Carbowax 20M. Recoveries of chloroform added to toothpastes range from 95 to 104%.
Quantitative Determination of Poly chlorinated Biphenyls—A Computer Approach
Authors: Zobel Michael G R 
Published: February 2020

Abstract
A computer method is presented which enables polychlorinated biphenyl (PCB) residue chromatograms to be resolved and quantitatively measured in terms of a sum of different standard Aroclors. The Aroclors 1242, 1254, and 1262 were used in this work, but the method is capable of using any number or combination from 1 Aroclor upward. The program constructs test chromatograms from standard peak heights, and, by a minimizing procedure, selects the test chromatogram nearest to the unknown. Spuriously large or small peak heights, caused by interfering compounds or metabolism, are automatically sorted and rejected. The results are output as both total and compositional PCB content, and in the form of a constructed line chromatogram. The method was applied to cardboard and pulp samples of widely differing PCB content. A modified program has enabled analysis of a heavily metabolized pork fat sample by comparing only the later eluting peaks. The “pre-metabolism” PCB content was estimated.
Congener Development in Bourbon Whisky Matured at Various Proofs for Twelve Years
Authors: Baldwin Sidney , Andreasen Arthur A 
Published: February 2020

Abstract
The color intensity and congener concentration of bourbon whiskies matured for 12 years decreased as the entry proof increased from 109 to 155°, except for fusel oil content which remained approximately constant. The average annual cumulative evaporation loss rates, in per cent of original proof gallons/year, were approximately the same at all 6 proofs, i.e., 3.0%/year or 3 6% for the 12 year period. The relative rates of formation of total barrel-derived material, a newly proposed parameter defined as the sum of the increase in volatiles and nonvolatiles in an aged product, were quite similar for comparable time intervals regardless of entry proof. There was greater variation among the relative rates of formation of individual congeners at the different entry proofs. Although all congeners except esters attained at least 5 0% of their ultimate (twelfth year) value during the first 4 years, it appears that appreciable congener development continues at least through 12 years. Esters developed linearly over the 12 year period.
Determination of Trace Amounts of Thallium in Urine, Using the Mercury-Film Electrode and Differential Pulse Anodic Stripping Voltammetry
Authors: Curtis Arvine R 
Published: February 2020

Abstract
Thallium concentrations as low as 0.2 ppb may be easily and accurately measured with no sample preparation. The urine is pipetted directly into the electrolysis cell containing 0.1M HClO4 and deaerated; a 2 min electrolysis is performed, and the thallium is oxidized from the mercury-thallium amalgam, using differential pulse anodic stripping voltammetry. The standards are spiked thallium-free urine solutions; thus the samples and standards reflect each other closely, and as the standard curves are repeatable to within ± 5% (down to 2 ppb thallium), the recoveries range from 95 to 105%. Lead is not a serious interference; however, cadmium does interfere and a complexing agent must be used when determining traces of thallium in the presence of cadmium.
A Modification in the Official Methods for the Determination of Metals in Feeds and Fertilizers by Atomic Absorption Spectrophotometry
Authors: Everson Robert J 
Published: February 2020

Abstract
A modification in the official methods for the determination of metals in feeds and fertilizers by atomic absorption spectrophotometry is presented. In lieu of digesting the samples in beakers and then filtering them into a volumetric flask, the samples are digested in a 250 ml volumetric flask, and then diluted to volume. This procedure and subsequent handling eliminates losses from spattering, transferring the sample from the beaker to the volumetric flask, and failure to thoroughly rinse the filter paper. The results obtained by the modification appear comparable to those obtained by the official methods.
Polycyclic Aromatic Hydrocarbon Profile Analysis of High-Protein Foods, Oils, and Fats by Gas Chromatography
Authors: Grimmer Gernot , Böhnke Heinz 
Published: February 2020

Abstract
A method is described for the determination of polycyclic aromatic hydrocarbons (PAHs) with 3–7 rings in (I) meat, poultry, fish, and yeast; and (II) oils and fats. The extraction of PAHs from group I is incomplete, and, therefore, group I samples must be dissolved homogeneously by saponification in 2N methanolic potassium hydroxide. The PAHs are concentrated by liquid-liquid extraction (methanolwater - cyclohexane, N,N - dimethylformamide - water-cyclohexane) and by column chromatography on Sephadex LH 20. The PAHs are separated by high-performance gas-liquid chromatography (GLC) with columns containing 5% OV-101 on Gas-Chrom Q and estimated by integration of the flame ionization detector signals in relation to an internal standard (3,6-dimethylphenanthrene and/or benzo(b)chrysene). The sensitivity is significantly higher than that obtained with ultraviolet spectroscopic methods. The reproducibility and margin of error were tested with meat samples fortified with 11 PAHs and with samples of sunflower oil. The method was further applied to meat, smoked fish, yeast, and unrefined sunflower oil. All samples investigated contained more than 100 PAHs (characterized by mass spectrometry) of which only the main components were determined: phenanthrene, anthracene, fluorene, fluoranthene, pyrene, benzo (a) anthracene, chrysene, benzo (b) fluoranthene + benzo (j) fluoranthene + benzo(k)fluoranthene, benzo(e)pyrene, benzo (a) pyrene, perylene, dibenz(a,j)anthracene, dibenz(a,h)anthracene + indeno (1,2,3-cd)pyrene, benzo(ghi)perylene, anthanthrene, and coronene. In contrast to other methods, the GLC profile analysis allows the recording of known and unknown PAH peaks simultaneously and also allows a compilation of all PAHs.
Semiautomated Analysis of Ergonovine Maleate or Methylergonovine Maleate Tablets and Injections by Colorimetric or Fluorometric Systems
Authors: Kirchhoefer Ross D , Wells Clyde E 
Published: February 2020

Abstract
Two semiautomated analytical systems have been developed to determine ergonovine and methylergonovine maleate in single tablets and injections. The active ingredient is dissolved in a tartrate buffer. In the fluorometric method the stream is automatically diluted with tartrate buffer and excited with ultraviolet light; the resulting fluorescence is measured and recorded. In the colorimetric method, the stream is automatically made basic with sodium hydroxide and extracted with n-butanol. The extract is mixed with p-dimethylaminobenzaldehyde reagent. After reaction, the solution is mixed with sodium nitrite solution, and the developed color is measured at 550 nm. Recoveries of 100% were obtained from spiked placebos. Standard deviations for powdered tablet and injection samples ranged from 0.63 to 1.24%. Comparisons with the USP XVIII methods are presented.
Simultaneous Assay for Six Alkaloids in Opium, Using High-Performance Liquid Chromatography
Authors: Ziegler Howard W , Beasley Thomas H , Smith David W 
Published: February 2020

Abstract
A method is described for the quantitative determination of morphine, codeine, cryptopine, thebaine, papaverine, and narcotine in opium by high-performance liquid chromatography. The alkaloids are isolated from a dilute acid extract by adsorption on an Amberlite XAD-2 resin column and eluted first with methanol and then with chloroform-methanol ( 3+1 ) . After solvent removal by reduced pressure evaporation, the alkaloids are redissolved in chloroformmethanol ( 3+1 ) . The sample solution, plus brucine as an internal standard, is injected onto a Corasil II column and eluted with hexane that is gradient programmed with a solution of chloroform-methanol-diethylamine ( 100+300+1). The absorbances of the separated alkaloids are continuously monitored at 254 nm, using a flow-through ultraviolet double-beam photometer.
Collaborative Study of a Semiautomated Method for the Determination of Crude Protein in Animal Feeds
Authors: Noel Rodney J , Hambleton Larry G 
Published: February 2020

Abstract
A semiautomated method consisting of digestion of animal feeds in a block digestor and determination of ammonia by ammonia-salicylate reaction has been studied collaboratively, along with the official final action Kjeldahl method, sec. 7.016. Each collaborator analyzed 16 feed samples, tryptophan, ammonium dihydrogen phosphate NBS standard, and ammonium sulfate primary standard. Statistical analysis showed that the 2 methods agreed. The semiautomated method has been adopted as official first action.
Separation of Pesticide Residues from Lipids Prior to Gas-Liquid Chromatographic Analysis
Authors: Lea Robert 
Published: February 2020

Abstract
Lipids are separated from dieldrin, endrin, and p,p′-DDE residues by saponification in ethanolic sodium hydroxide, acidification with dilute sulfuric acid, and adsorption chromatography on deactivated alumina, using petroleum ether as the eluant. Dieldrin, endrin, and p,p′-DDE are efficiently recovered (95–102%), and p,p′-DDT is converted to p,p′-DDE, which is then recovered with high yield (90–96%). Extremely low lipid carryover (&lt;0.3–0.5%) is observed for 0.5–1.0 g samples of chicken fat.
High-Pressure Liquid Chromatographic Determination of Vitamin D3 in Resins, Oils, Dry Concentrates, and Dry Concentrates Containing Vitamin A
Authors: Hofsass Henry , Grant Anne , Alicino Nicholas J , Greenbaum Sheldon B 
Published: February 2020

Abstract
A high-pressure liquid chromatographic (HPLC) procedure has been developed for the determination of vitamin D3 in resins, oils, dry concentrates, and dry concentrates containing vitamin A. Specificity of the method for vitamin D3 in the presence of isomers and other related constituents was shown by ultimate recovery of the vitamin D3 and the individual constituents and their characterization by other methods such as ultraviolet spectrophotometry. Precision and accuracy are within 2%, and as many as 20 determinations may be completed in a working day. Excellent agreement with the official AOAC biological assay was found. A comparison of the response of isomers of vitamin D3 by the HPLC method vs. other instrumental and chemical procedures shows HPLC to be the most specific method for determining the bioactive isomers.
High-Performance Liquid Chromatographic Determination of Warfarin
Authors: Billings Toby J , Hanks Alan R , Colvin Billy M 
Published: February 2020

Abstract
A high-performance liquid chromatographic (HPLC) method for determining warfarin, 3-(α-acctonylbenzyl)-4-hydroxycoumarin, in rodenticide formulations is described. Samples containing warfarin are ground, extracted 1 hr on a rotary shaker with dioxane-1% sodium pyrophosphate (85+15), centrifuged, and filtered. The filtrate is injected onto an HPLC column containing C18-μBondapak with a precolumn of C18-Corasil. The eluting solvent is 0.0025N H3PO4-methanol (1+2) at a flow rate of 1.5 ml/min. Chromatography is complete within 10 min and warfarin is detected by ultraviolet absorption at 283 nm. Results indicate good reproducibility with a 2.4% average coefficient of variation for a variety of commercial samples containing 0.025–0.5% warfarin. This method is also applicable to samples containing sodium warfarin. The HPLC method is rapid and specific. Results obtained agree with those from more commonly employed ultraviolet spectrophotometric methods.
Detection of Sprouted Wheat by a Rapid Colorimetric Determination of α-Amylase
Authors: Mathewson Paul R , Pomeranz Yeshajahu 
Published: February 2020

Abstract
A method is described for the rapid, convenient detection or estimation of sprout-damaged wheat by determining its α-amylase content colorimctrically. A commercially available substrate in the form of dyed amylose tablets is used. The extent of sprout damage can be determined qualitatively, or quantitatively when actual α-amylase concentration is required. Amylase content is determined by visual comparison with prepared colored standards or by spectrophotometric analysis. The method requires only 5 min incubation time and no elaborate equipment, and is sufficiently simple for use at locations having minimal laboratory facilities.
Modified AOAC Method for Determination of Moisture in Corn Sirups
Authors: Engel C Earl 
Published: February 2020

Abstract
Investigation of the current AOAC vacuum oven filter aid method for determining moisture in corn sirups revealed that minor modifications are needed to make the method applicable to the com sirups now produced by the wet milling industry. The proposed method incorporates AOAC methodology which requires a drying temperature of 70°C for fructose-containing materials and continues the drying temperature of 70°C for high dextrose products. Other corn sirups will continue to be dried at 100°C. In addition, the proposed method incorporates some of the improvements which were evident in the original publication but were not included in the current AOAC method. The modified method has been adopted as official first action.
Identification of Polychlorinated Styrene Compounds in Heron Tissues by Gas-Liquid Chromatography-Mass Spectrometry
Authors: Reichel William L , Prouty Richard M , Gay Martha L 
Published: February 2020

Abstract
Unknown compounds detected in Ardea herodias tissues are identified by gas-liquid chromatography-mass spectrometry as residues of octachlorostyrene. Heptachlorostyrene and hexachlorostyrene were tentatively identified.
Determination of Protein Nitrogen in Plants
Authors: Gaines T Powell 
Published: February 2020

Abstract
A method is described for determining protein nitrogen (PN) in plants. Plant tissue extracted with 0.5% acetic acid to remove nonprotein nitrogen (NPN) prior to Kjeldahl analysis gave results very close to true PN, whereas AOAC crude PN method 2.049 gave results much too high. True PN was determined as the mean of 3 independently derived values and was used as the basis for comparing the proposed PN method with AOAC method 2.049. Failure of the AOAC method to differentiate between NPN and/or inorganic ammoniacal N and actual PN causes values derived from this method to be too high when it was used to determine PN in plants.
Identification of Post-Explosion Residues
Authors: Kaplan Meyer A , Zitrin Shmuel 
Published: February 2020

Abstract
A scheme for the identification of explosive residues from post-explosion scenes is described. The first step consists of organic and inorganic extractions rather than microscopic examination. The methods of identification which follow include thin layer and gas-liquid chromatography, infrared and ultraviolet spectroscopy, and chemical tests. The system, which has been used routinely by the Israel Police for 5 years, deals efficiently with standard military explosives as well as with home-made, improvised mixtures.
Confirming Heptachlor and Heptachlor Epoxide in Food Samples by Gas-Liquid Chromatography of Their Photo derivatives
Authors: Ward Paul M 
Published: February 2020

Abstract
The food sample extract is cleaned up on a Florisil column and the 6% ethyl ether in petroleum ether eluate is subjected to repeated concentrations, using a micro-Snyder column, to expel volatile materials that absorb ultraviolet (UV) light. The sample and standard solutions of heptachlor and heptachlor epoxide are placed in quartz cells and exposed to UV radiation in the dark. Characteristic photoderivatives of the respective pesticides which form in the sample extract are identified and measured by comparison with those formed in the irradiated standard solutions, using electron capture gas-liquid chromatography. Recoveries of the 2 pesticides from 13 products, fortified at levels from 0.01 to 0.3 ppm and determined after derivatization, ranged from 67 to 110%.
Rapid Digestion and Flameless Atomic Absorption Spectroscopy of Mercury in Fish: Collaborative Study
Authors: Munns Robert K , Holland David C 
Published: February 2020

Abstract
A collaborative study of the determination of mercury in fish has been completed in which wet oxidation of fish tissue in nitric acid, using vanadium as a catalyst, is compared with the AOAC official final action digestion technique, 25.103–25.105, involving a nitric-perchloric acid mixture. The study used tuna fish samples of known mercury content and included spike recovery studies in which methyl mercury solutions of known composition were provided to each laboratory. The study was designed to provide recovery information that bracketed the regulatory level of mercury in fish. The results indicate that the proposed digestion method is at least as precise and accurate as the AOAC method. The proposed method is also more rapid and less hazardous. It has been adopted as official first action.
Glucosinolates and Derived Products in Cruciferous Vegetables: Gas-Liquid Chromatographic Determination of the Aglucon Derivatives from Cabbage
Authors: Daxenbichler Melvin E , VanEtten Cecil H 
Published: February 2020

Abstract
A procedure is described for identifying and quantitatively determining the gīucosinolates found in edible cabbage. The intact glucosinolates are extracted and their aglucons are released into solvent after a special enzymatic hydrolysis step. The resulting isothiocyanates and oxazolidinethiones are separated by a gas-liquid chromatographic procedure that allows the individual aglucons to be identified and their amounts to be estimated by comparison with an internal reference.
Application of Reverse Phase Ion-Pair Partition Chromatography to Drugs of Forensic Interest
Authors: Lurie Ira 
Published: February 2020

Abstract
A method is described for determining a wide range of abused drugs by using 1 column, a single isocratic system, and a fixed wavelength (254 nm) ultraviolet detector. Paired-ion chromatography is performed on a reverse phase μBondapak C18 column. Acidic, basic, and neutral drugs, including their corresponding salts, can be determined without prior cleanup. A counter ion, 1-heptane sulfonate, is dissolved in the aqueous organic mobile phase to give a final pH of approximately 3.5. This technique is applicable to ergot alkaloids, phenylethylamines, opium alkaloids, local anesthetics, barbiturates, and other drugs of forensic interest. Five major opium alkaloids in gum opium, namely, morphine, codeine, thebaine, narcotine, and papaverine, can be separated in approximately 20 min.
Microdetermination of Tryptophan in Compounded Poultry Rations
Authors: Datta Salil C 
Published: February 2020

Abstract
A reliable method for the microdetermination of tryptophan in compounded poultry rations has been developed. Samples are hydrolyzed with Ba(OH)2, and the hydrolysate is passed through a Dowex-50 column to remove the salts and soluble carbohydrates. N-l-Naphthylethylenediamine is added to the purified feed hydrolysate, and color is read at 530 nm.
Balancing Patient Care and Force Protection at Military Medical Treatment Facilities
Authors: Nardi Sean , Ferguson Brian , Peck Sean , Ross Elliot , Walrath Benjamin 
Published: February 2020

ABSTRACT

Objectives
This study aimed to identify delays of care due to base access security protocols at a stateside military medical treatment facility (MTF) for patients with a time-sensitive medical condition who are seeking emergency medical care at the MTF.

Methods
We retrospectively analyzed emergency medical services (EMS) run reports from January 1, 2017 to November 12, 2017 to hospital access points to assess patients who were initially denied access to the MTF. Time from EMS activation until patient delivery at the emergency department, number of time-sensitive complaints, number of time-sensitive conditions, and number of unauthorized access attempts are reported.

Results
During the 11-month period of review, 42 delays of care related to EMS activation by the sentry at hospital access points were identified. Of the 42, 14 were associated with a time-sensitive complaint, 2 with time-sensitive conditions, and none were unauthorized access attempts.

Conclusion
We identify the potential for patient harm due to delays in care resulting from the security protocols at our MTF. A review of force protection requirements with consideration for their impact on patient safety, especially in cases of time-sensitive conditions, has been conducted.
It Totally Possibly Could Be: How a Group of Military Physicians Reflect on Their Clinical Reasoning in the Presence of Contextual Factors
Authors: Konopasky Abigail , Ramani Divya , Ohmer Megan , Battista Alexis , Artino Anthony R , McBee Elexis , Ratcliffe Temple , Durning Steven J 
Published: February 2020

ABSTRACT

Introduction
Contextual factors (eg, diagnostic suggestion and burnout) can affect physician clinical reasoning performance, leading to diagnostic error. Yet, contextual factors have only recently been studied and none of that work focused on how physicians appraise (ie, evaluate) the clinical situation as they reason. The purpose of this qualitative study was to use appraisal to describe the effect of contextual factors on clinical reasoning.

Materials and Methods
Physicians (n = 25) either viewed two video cases or participated in two live scenarios, one with contextual factors and one without. Afterwards, they completed a “think-aloud” reflection while reviewing the cases. Transcribed think-alouds were coded for appraisal markers, comparing cases with and without contextual factors.

Results
When contextual factors were present, participants expressed more emotional evaluation and uncertainty about those emotions. Across all types of cases, participants expressed uncertainty about the case and assessed what “could” or “would” have gone differently.

Conclusions
This study suggests that one major effect of contextual factors may be that they induce emotions, which may affect the process of clinical reasoning and diagnostic error. It also suggests that uncertainty may be common in clinical practice, and we should thus further explore its impact.