bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas Chromatographic Analysis of Amino Acids as the jV-Heptafluorobutyryl Isobutyl Esters
Authors: MacKenzie Samuel L
Published: February 2020

The N-heptafluoroburyryl isobutyl derivatives of proteic amino acids are well resolved by gas chromatography and form the basis of a convenient, rapid assay. The derivatives are prepared by acid-catalyzed esterification at 120°C for 20 min in 3N HCl-isobutanol followed by acylation with heptafluorobutyric anhydride at 150°C for 10 min. The reaction sequence is performed without any transfers or extractions and thus is compatible with microscale analysis. A complete proteic amino acid profile can be completed in less than 20 min by using a packed column or less than 10 min by using a capillary column in combination with an elevated oven temperature program rate. Physiological sample matrixes, which frequently contain a complex mixture of components, and thus require maximum resolution, can be assayed in less than 1 h using a program rate of 4°C/min. A capillary column is recommended for this application. Capillary column chromatography, in combination with a nitrogenspecific detector, is useful for identifying and assaying nonproteic amino acids in physiological sample matrixes. Frequently, a prior cleanup of the sample can be avoided.
Analysis of Amino Acids by Gas Chromatography as the N-Trifluoroacetyl η-Butyl Esters
Authors: Gehrke Charles W , Kuo Kenneth C , Kaiser Floyd E , Zumwalt Robert W
Published: February 2020

This presentation describes amino acid analysis with the gas chromatographic method and experimental conditions using the N-trifluoroacetyl n-butyl ester derivatives; the study we describe here was undertaken to compare gas chromatographic (GC) and ion-exchange chromatographic (IEC) analyses of amino acids in hydrolysates of 9 diverse sample types to gain insight into effects of these 2 chromatographic methods of analysis on variation in amino acid results. Our study showed that values for samples prepared by 2 separate laboratories using the same procedure were generally in good agreement when all of the hydrolysates were analyzed by a single laboratory using a single method of analysis. To compare results from gas chromatography with those from ion-exchange chromatography analyses were performed by 2 different laboratories on the same hydrolysates and on different hydrolysates prepared by the same method by both laboratories. The data demonstrate that GC and IEC can be expected to yield essentially identical results when applied to the same hydrolysate. Agreement is so close that interlaboratory differences in hydrolysate preparation of the same sample contribute as much to variation in amino acid results as does the method of analysis, a fact which should be noted in planning collaborative studies.
Most Probable Number Method for Isolation and Enumeration of Staphylococcus aureus in Foods: Collaborative Study
Authors: Lancette Gayle A , Lanier John
Published: February 2020

Enumeration of Staphylococcus aureus in foods was collaboratively studied by comparing the present AOAC final action method, 46.062, which uses trypticase soy broth with 10% NaCl to a proposed replacment method which uses the same broth with 1% sodium pyruvate added. Fifteen collaborators analyzed uninoculated samples of milk, tuna salad, and ground turkey, as well as samples inoculated with low (102 cells/g), middle (104 cells/g), and high (106 cells/g) levels of S. aureus. The samples were frozen immediately to maintain the inoculated level of S. aureus in the food. A different strain of S. aureus was used for each food; heat-stressed S. aureus cells were used to inoculate the milk samples. The pyruvate-amended broth significantly (α = 0.05) increased enumeration of low, middle, and high levels of S. aureus from milk and ground turkey, and from tuna salad at middle and high levels. The pyruvate-amended media method has been adopted official first action to replace method 46.062
Liquid Chromatographic Determination of Penicillin V Potassium in Tablets and Powders for Oral Solution
Authors: Mopper Barry
Published: February 2020

A reverse-phase liquid chromatographic method is described for the assay of penicillin V potassium in tablets and powders for oral solution. Under isocratic conditions, the combined use of an octadecjrlsilane column, with a mobile phase composed of acetonitrile-methanol- O.OlM monobasic potassium phosphate (21 + 4 + 75, v/v), and photometric detection at 225 nm, separated penicillin V potassium from excipients, related compounds, and degradation products. Sulfadimethoxine was used as an internal standard. Detector responses were linearly related to concentrations of penicillin V over the range 25-225 μg/mL (r = 0.99997). Standard addition recoveries ranged from 98.8 to 99.9% (mean 99.5%, n = 8) for tablets and from 97.9 to 101.6% (mean 99.8%, n = 8) for powders for oral solution. The liquid chromatographic assay results were compared with those obtained by the official iodometric titration method. The proposed method is simple, selective, stability-indicating, and free from interference by excipients and degradation products
Gas Chromatographic Determination of Isofenphos in Technical and Formulated Products: Collaborative Study
Authors: Terry Daniel E
Published: February 2020

A gas chromatographic method for the determination of isofenphos (OFTANOL®) in isofenphos technical and liquid formulations has been developed and collaboratively studied by 11 laboratories. Two technical samples and 2 liquid flowable samples were analyzed after shaking/extracting in methanol which contained diisobutyl phthalate as an internal standard. The extracts were analyzed by gas chromatography using an SP-2100 column and either flame ionization or thermal conductivity detection. Coefficients of variation were 0.57 and 1.27% for the technical and formulated products, respectively. The GC method has been adopted official first action as a AOACCTPAC method.
Determination of Nitrogen and Protein Content of Meat and Meat Products
Authors: Benedict Robert C
Published: February 2020

Chemical and instrumental methods for determination of nitrogen and protein are reviewed for their mode of action and utility in analysis of meat proteins and products. Although the Kjeldahl digestion method is satisfactory for determining total nitrogen, it is imprecise for determining total protein content. Presence of variable amounts of nonprotein nitrogenous components and of connective tissue proteins such as collagen and elastin produces error if the formula (N x 6.25) is used to calculate crude protein. Such fibrous proteins have higher nitrogen levels (over 18%) than other muscle proteins (about 16%), and a higher than actual protein value will be determined unless a lower conversion factor is used to correct for their content. To determine meat protein content more accurately, a combination of Kjeldahl determination with one or more additional tests to correct for nonprotein and fibrous protein content is recommended. The choice of the additional method(s) is based on the user's requirement for protein characterization, available time, type of meat product, and sample size.
Wiley Led the Way: A Century of Federal Honey Research
Authors: White Jonathan W
Published: February 2020

Jonathan W. White, Jr, received the AOAC Harvey W. Wiley Award at the 100th AOAC Annual International Meeting and Exposition in Scottsdale, AZ, September 15, 1986. In 1942, after earning his Ph.D. at Purdue University, White became assistant chemist at the Eastern Regional Research Center (ERRC) of the U.S. Department of Agriculture at Wyndmoor, PA, where he spent almost his entire professional career. In 1948, he began the extensive research on honey for which he was selected as the 1986 Wiley Award recipient. He was named chief of the ERRC Plant Products Laboratory in 1965; 10 years later he requested reassignment to conduct research on the detection of adulteration of honey by high-fructose corn syrup. He retired from USDA in 1978 and until recently headed a honey testing service called Honeytech, Inc. White was elected a Fellow of AOAC in 1969 and was named Associate Referee of the Year in 1977
Gas Chromatographic Determination of Calcium Propionate Added as Preservative to Bread
Authors: Lamkin William M , Unruh Natalie C , Pomeranz Yeshajahu
Published: February 2020

A simple and rapid gas chromatographic procedure was developed for determining low concentrations of propionate added as a preservative to bread. A bread sample to be analyzed was ground in a meat grinder with a 3 mm hole plate and finely divided by rubbing through a No. 8 sieve. The propionate was then extracted into 0.050M formic acid in a blender at low speed for 5 min, and an aliquot of a filtrate was analyzed directly by gas chromatography. Chromatographic separation was accomplished on a Carbopack C column coated with 0.3% (w/w) Carbowax 20M and 0.1% (w/w) phosphoric acid. Less than 0.2 ppm propionic acid could be detected in the aqueous extract. Over the range of 0.03-0.23% calcium propionate, average relative error was —1.20% with an average coefficient of variation of 2.02%.
Total Nitrogen Determination of Various Sample Types: A Comparison of the Hach, Kjeltec, and Kjeldahl Methods
Authors: Watkins Kevin L , Veum Trygve L , Krause Gary F
Published: February 2020

Conventional Kjeldahl analysis with modifications, Kjeltec analysis with block digestion and semiautomated distillation, and the Hach method for determining nitrogen (N) were compared using a wide range of samples. Twenty different sample types were ground and mixed. Each sample type was divided into 5 subsamples which were analyzed for N by each of the 3 methods. In each sample type, differences (P < 0.05) were detected among the 3 N determination methods in 5 of the 20 N sources analyzed. The mean N content over all 20 samples was higher with Kjeldahl analysis (P < 0.05) than with Kjeltec, while Hach analysis produced intermediate results. Results also indicated that the Hach procedure had the greatest ability to detect differences in N content among sample types, being more sensitive than either other method (P < 0.05).
Ceramic Fiber as Filter Aid in Determination of Acid-Insoluble Lignin in Forages
Authors: McQueen Ralph E
Published: February 2020

Ceramic fiber was found to be a suitable alternative to asbestos in determining the acid-insoluble lignin content of 59 forages by AOAC official final action method 7.074-7.077. Replacement of asbestos is necessary because it is a recognized carcinogen. Blank values for ceramic fiber were less than those for asbestos, and repeatability of duplicate lignin determinations was similar for both filter aids. Lignin content (%) by the ceramic fiber method (X), over the range 0.74-12.63%, was highly correlated (0.997) with that using the asbestos method (Y) by the relationship: Y = 1.008X - 0.093. Correction of forage lignin estimates using ceramic fiber is necessary if they are compared with those obtained using asbestos because of the negative Mas of 0.093%.
Improved Method for Determination of Volatile Nitrosamines in Baby Bottle Rubber Nipples and Pacifiers
Authors: Sen Nrisinha P , Seaman Stephen W , Kushwaha Santosh C
Published: February 2020

A method is described for determining volatile nitrosamines in baby bottle rubber nipples and pacifiers. The method consists of (a) overnight soaking of the sample with dichloromethane in the presence of propyl gallate, an inhibitor for artifactual formation of nitrosamines; (b) extraction with dichloromethane using an ambient temperature column procedure; (c) distillation from aqueous alkali; (d) extraction of the aqueous distillate with dichloromethane and concentration of the extract using a Kuderna-Danish concentrator; and (e) final analysis by gas chromatography with detection by thermal energy analyzer. Major improvements over other published methods include a simpler extraction, a more efficient distillation and concentration to minimize losses, and incorporation of propyl gallate inhibitor as well as of a test to detect unsuitable dichloromethane solvent that otherwise might lead to artifactual formation. The method is highly accurate (~90% recovery) and precise (av. CV = 4.7% at >9 ppb levels) and is applicable to determination of nitrosamines in both rubber- and plastic-based products.
Liquid Chromatographic Determination of Melamine in Beverages
Authors: Ishiwata Hajimu , Inoue Takiko , Yamazaki Takeshi , Yoshihira Kunitoshi
Published: February 2020

A liquid chromatographic method is described for the determination of melamine in beverages. Melamine is separated by column chromatography using cation and anion exchange resin and determined by ion-pair liquid chromatography using an ODS column and a mixture of acetonitrile and 0.05M phosphate buffer (pH 3.0) containing 0.005M sodium 1-laurylsulfate (1 + 4, v/v) as mobile phase. Recoveries of melamine ranged between 90.3 ± 7.8 and 102.1 ± 5.6% at levels of 0.6 to 2.4 ppm in 4 kinds of beverages. The quantitation limit was 2.5 μg melamine in 50 mL beverage. The method was applied to the migration test of melamine from melamine-formaldehyde resin products to the beverages.
Determination of Sorbic, Dehydroacetic, and Propionic Acids in Cheese by Liquid Chromatography and Gas Chromatography
Authors: Saito Isao , Oshima Harumi , Kawamura Norihisa , Uno Keiichi , Yama Masuo
Published: February 2020

A convenient and accurate method is presented for the determination of sorbic, dehydroacetic, and propionic acids in cheese by liquid chromatography and gas chromatography. The volatile acids are separated from cheese by steam distillation. Sorbic and dehydroacetic acids are determined by liquid chromatography using a reverse phase column and a mobile phase mixture (30 + 70) of methanol and 0.02M phosphate buffer, pH 7.2, containing 0.005M tetrabutyl ammonium. The effluent is monitored at 235 nm. After the distillate is acidified with formic acid, propionic acid is determined by gas chromatography with a flame ionization detector using a Porapak QS column. Average recoveries of sorbic, dehydroacetic, and propionic acids ranged from 92.3 to 99.5%. By this method, the acids could be determined without using organic solvent during extraction and cleanup.
Reverse Phase Liquid Chromatographic Assay for Calcium Pantothenate in Multivitamin Preparations and Raw Materials
Authors: Timmons Jo Anne , Meyer John C , Steible Daniel J , Assenza Sebastian P
Published: February 2020

A reverse phase liquid chromatographic (LC) method has been developed for the assay of calcium pantothenate in commercial multivitamin tablet formulations and raw materials. The assay was validated according to the Pharmaceutical Manufacturers Association Quality Control HPLC Committee guidelines. The chromatographic system includes a C-18 column and a mobile phase consisting of 0.25M sodium phosphate buffer, pH 2.5, and acetonitrile (97 + 3 v/v). The column effluent is monitored by UV detection at 205 nm. The sample preparation involves only extraction in water followed by filtration. The method is stability-indicating with a detection limit of approximately 50 ng/mL of the calcium pantothenate in the samples. The system is linear from at least 0.02 to 0.10 mg/mL. The mean recovery of spiked placebos ranged from 98.7 to 99.8%. The within-day precision of the assay on finished products (N = 6) ranged from 0.3 to 2.0% CV. A system suitability criterion for resolution is based on the separation between calcium pantothenate and 2 closely eluting compounds, saccharin and a saccharin degradation product, 2-sulfamoylbenzoic acid.
Evaluation of Selected Enzymes for Thiamine Determination
Authors: Defibaugh Phillip W
Published: February 2020

Seven commercially available enzymes were studied for suitability as substitutes in the AOAC thiamine determination, because the enzyme Takadiastase used in the method has not been available since 1976, and alternative enzymes were likewise unavailable or unsuitable for releasing thiamine from its phosphate esters. Four factors (substrate ester, enzyme level, time/temperature, and pH) at 2 levels were studied in a 24 factorial arrangement of treatments. Data were expressed in terms of mean percentage conversion (MPC) and were statistically evaluated by analysis of variance. Significant main effects and any interactions among treatments were calculated. Takadiastase and a-amylase (Miles) with MPCs of 101 and 102, respectively, appeared effective in dephosphorylation within method parameters. Potato phosphatase appeared marginally suitable. Wheat germ phosphatase, α-amylase (Sigma), Mylase 100, and Clarase 40,000 were judged unacceptable as enzyme substitutes.
Spectrophotometric Determination of Ascorbic Acid in Canned Fruit Juices, Cordials, and Soft Drinks with Iron(III) and 1,10-Phenanthroline as Reagents
Authors: Lau Oi-Wah , Luk Shiu-Fai
Published: February 2020

A simple and accurate spectrophotometric method has been developed for the determination of ascorbic acid in canned fruit juices, cordials, and soft drinks, based on the reduction of iron(III) by ascorbic acid to iron(II), which is then complexed with 1,10-phenanthroline. Background correction is necessary for most samples and can be achieved by copper(II)-catalyzed oxidation of the acid. The calibration graph was linear from 0 to 8 μg/mL of ascorbic acid with a slope of 0.12/ppm. The precision for the determination of ascorbic acid in a lemon drink containing 210 μg/mL of the acid was 0.9%. Many ingredients commonly found in fruit juices, cordials, and soft drinks do not interfere; however, tannic acid, pyrogallol, and sulfite interfere with the method. A wide range of samples was analyzed for ascorbic acid content by the proposed method. The samples included mango and lemon tea drinks and also grapefruit juices, for which no background correction is needed.
Limitations of the A-IM Method for Fecal Coliform Enumeration in the Pacific Oyster (Crassostrea gigas)
Authors: Kaysner Charles A , Weagant Stephen D
Published: February 2020

Use of the A-IM method, which was originally devised for testing water samples, has recently been extended for enumeration of fecal coliforms and Escherichia coli in shellfish and other food products. Results of our study indicate that while this method is reliable for analysis of growing waters, the use of the A-IM method for testing Pacific oysters may be less reliable because bacteria not belonging to the coliform group but which are sometimes present in these animals also give a positive reaction.
Square-Wave Voltammetric Determination of Acetaldehyde in Povidone
Authors: Lanniello Robert M , Colonnese Regina , Machnicki Nancy
Published: February 2020

A rapid, precise, and accurate method is described for the determination of acetaldehyde in povidone (polyvinyl pyrrolidone). The sample is dissolved in a basic aqueous electrolyte and analyzed using square-wave voltammetry. The proposed method allows for direct measurement of acetaldehyde under gentle conditions, thus avoiding loss of analyte due to volatility of acetaldehyde. The method is specific for acetaldehyde in the presence of other aldehydes and povidone process impurities.
Colorimetric Determination of Terbutaline Sulfate and Orciprenaline Sulfate via Nitrosation and Difference Spectrophotometry
Authors: El-Sadek Mohamed E , Abdel Latef Hisham E , Aboul Khier Afaf A
Published: February 2020

A colorimetric method is proposed for determination of terbutaline sulfate, orciprenaline sulfate, and their dosage forms. The suggested method depends on nitrosation of the 2 drugs by using sodium nitrite and hydrochloric acid. Addition of sodium hydroxide increases the intensity of the color developed. The difference between absorption values measured in acid and alkaline media is taken as a measure of concentration. Variables were carefully studied and optimized. Results for both compounds adhered to Beer's law over the range 2- 28 μg/mL. The method has proved to be accurate and precise for analysis of pharmaceutical dosage forms.
Rapid Liquid Chromatographic Determination of Dimetridazole and Ipronidazole in Swine Feed
Authors: Roybal Jose E , Munns Robert K , Hurlbut Jeffrey A , Shimoda Wilbert , Morrison Thomas R , Vieira Cassandra L
Published: February 2020

A simple and rapid method is described for the determination of dimetridazole (DMZ) and ipronidazole (IPR) in swine feeds at various levels (0.11-110 ppm). The drugs are released from feed by prewetting with a buffer, followed by extraction with either methanol or methylene chloride, depending on the drug level; if necessary, an acid-base cleanup is used before the liquid chromatographic analysis. The analytes are separated on a C18 column and monitored at 320 nm for detection and quantitation. Recoveries of DMZ from several feed formulations averaged 108% at the 92.8 ppm level with a standard deviation (SD) of 4.00% and a coefficient of variation (CV) of 3.70%, 101% at the 11.2 ppm level with an SD of 11.9% and a CV of 11.8%, and 100% at the 0.112 ppm level with an SD of 9.27% and a CV of 9.25%. Recoveries of IPR averaged 77.1% at the 12.9 ppm level with an SD of 1.75% and a CV of 2.27%; IPR recoveries averaged 35.2% at the 0.129 ppm level with an SD of 3.39% and a CV of 9.63%.
Standardization of Bacterial Numbers on Penicylinders Used in Disinfectant Testing: Interlaboratory Study
Authors: Cole Eugene C , Rutala William A , Samsa Gregory P
Published: February 2020

An interlaboratory study was conducted to evaluate a method of standardizing bacterial numbers on penicylinders used in the AOAC use-dilution method (4.007-4.015) of disinfectant testing. Eight participating laboratories followed a broth adjustment method using their media and stock cultures of Staphylococcus aureus ATCC 6538, Salmonella choleraesuis ATCC 10708, and Pseudomonas aeruginosa ATCC 15442. The culture broths that were used to inoculate the penicylinders were incubated for 48 h at 37°C after several (4-6) 24 h passages. McFarland turbidity standards of 1.0 and 0.5 were used to adjust visually the cultures of S. aureus and P. aeruginosa, respectively. S. choleraesuis was used undiluted. The results showed significant variability in numbers of test bacteria which adhered to die penicylinders, with mean values of 1.6 x 106 for S. choleraesuis, 3.5 x 106 for S. aureus, and 8.2 x 106 for P. aeruginosa. The results from collaborating laboratories attempting standardization of bacterial numbers on penicylinders demonstrated significant interlaboratory and cylinder variation for all 3 test organisms.
Development of Mass Spectral Library of Trichothecenes Based on Positive Chemical Ionization Mass Spectra
Authors: Hewetson David W , Mirocha Chester J
Published: February 2020

The positive chemical ionization (PCI) mass spectra of the trichothecenes were acquired on a quadrupole mass spectrometer and assembled into a computer-searchable library. These were compared with spectra generated by electron impact ionization (EI) for ease and efficiency in identification. The trichothecenes were derivatized as trifluoroacetic acid esters, trimethylsilyl ethers, and heptafluorobutyric acid esters. The PCI spectra were found to be more useful than those generated by EI, although both types need careful evaluation in making an identification. Software programs called PBMULT and PEAKS were created. The former searches each scan generated, whereas the latter was designed to search only those scans found within selected peaks of the total ion current. The results of both search routines are spooled and stored in a retrievable file. The search can be conducted without attendance of the operator.
Spectrophotometric Estimation of Rifampin-Isoniazid Mixture in Dosage Form
Authors: Sharma Suresh C , Das Sukomal , Talwar Santosh K
Published: February 2020

A spectrophotometric method for the simultaneous determination of rifampin and isoniazid in dosage form is described. By using a mixtore of methanol and water (2 + 3) as solvent, the absorbance of the mixtures of rifampin and isoniazid is measured at 264 nm and 335 am. The concentration of each can then be calculated by solving 2 simultaneous equations. The procedure was successfully applied to a number of commercial samples; the results agreed well with those for compendial method.
Determination of Olaquindox Residues in Swine Tissues by Liquid Chromatography
Authors: Nagata Tomoko , Saeki Masanobu
Published: February 2020

A liquid chromatographic (LC) method is described for determination of olaquindox residues in swine tissues. The drug is extracted from tissues with acetonitrile, and the extract is evaporated to dryness. This residue is cleaned up by alumina column chromatography. LC analysis is carried out on a Nucleosil C18 column, and olaquindox is quantitated by ultraviolet detection at 350 nm. The average recoveries of olaquindox added to tissues at levels of 0.2, 0.1, and 0.05 ppm were 74.0, 68.6, and 66.3%, respectively. The detection limit was 2 ng for olaquindox standard and 0.02 ppm in tissues.
Determination of Nitrogen, Phosphorus, and Potassium in Water-Soluble Fertilizers by Inductively Coupled Plasma Emission Spectrometry
Authors: Nygaard Danton D , Sotera John J
Published: February 2020

A modification of an inductively coupled plasma (ICP) emission spectrometer is described that enables the simultaneous determination of nitrogen, phosphorus, and potassium in water-soluble fertilizers. A quartz extension tube is added to the ICP torch to exclude air from the plasma, thus allowing accurate nitrogen determination without adversely affecting sensitivity for other analytes. The modification also requires an 18 mg/L argon coolant flow to protect the tube from the heat of the plasma. Detection limits are 20 mg/L for nitrogen and 50 μg/L for phosphorus and potassium. Three NBS reference salts and 2 commercially available fertilizers were analyzed by the method, and results are in excellent agreement with known values.
Sample Preparation and Liquid Chromatographic Determination of Vitamin D
in Food Products
Authors: Bui Mai H
Published: February 2020

Vitamin D in different fortified foods is determined by using liquid chromatography (LC). Sample preparation is described for fortified skim milk, infant formulas, chocolate drink powder, and diet food. The procedure involves 2 main steps: saponification of the sample followed by extraction, and quantitation by LC analysis. Depending on the sample matrix, additional steps are necessary, i.e., enzymatic digestion for hydrolyzing the starch in the sample and cartridge purification before LC injection. An isocratic system consisting of 0.5% water in methanol (v/v) on two 5 /im ODS Hypersil, 12 x 0.4 cm id columns is used. Recovery of vitamin D added to unfortified skim milk is 98%. The results of vitamin D determination in homogenized skim milk, fortified milk powder, fortified milk powder with soybean, chocolate drink powder, and sports diet food are given
Spectrofluorometric Determination of BAY Vp 2674 Residues in Poultry Tissues
Authors: Waggoner T Bill , Bowman Malcolm C
Published: February 2020

A spectrofluorometric (SPF) method is described for determination of residues of BAY Vp 2674 in chicken and turkey tissues. The drug is extracted from tissues with dichloromethane-methanol. The organic extract is concentrated to near dryness and cleaned up by a series of partitionings with n-hexane, then dichloromethane against pH 2 buffer and dichloromethane against pH 12 buffer. The drug is partitioned into dichloromethane from pH 7 buffer and concentrated to dryness. The residue is dissolved in pH 3.5 buffer for SPF analysis at 282 nm (excitation) and 445 nm (emission). Recoveries of BAY Vp 2674 added to chicken and turkey tissues at levels of 0.05, 0.1, and 0.2 ppm range from 86 to 92% with a coefficient of variation of 3.4-10.1%. Detection limit is 0.02 ppm. A liquid chromatographic confirmatory procedure is also described, with ultraviolet and fluorescence detection
Determination of Cytotoxic Trichothecenes in Corn by Cell Culture Toxicity Assay
Authors: Porcher Jean-Marc , Lafarge-Frayssinet Christiane , Frayssinet Charles , Nurie Ahmed , Melcion Dominique , Richard-Molard Daniel
Published: February 2020

The great sensitivity of some cell species to toxins has been adapted to a direct biological determination of trichothecene contamination of food and feeds. The murine spleen lymphocyte stimulated by PHA (Phaseolus vulgaris phytohaemagglutinin) appeared to be the most convenient cells because of their particular sensitivity to cytotoxic trichothecenes and the opportunity to translate this cytotoxicity to immunosuppressive hazard, one of the most important concerns for trichothecenes. In this paper, the use of cell cultures was adapted for a survey of corn. The toxins were extracted by aqueous methanol, and the extract was defatted with hexane and purified on a silica gel/ Florisil column. This extract was then used for a gas chromatographic (GC) determination and the biological test. The growth of cells was measured by the incorporation of tritiated thymidine (3H Tdr), and the inhibition was expressed by the IC^: concentration of corn extract inhibiting by half the 3H Tdr incorporation. We have tested pure toxins, control corn, corn spiked with T-2 toxin, corn experimentally inoculated with toxigenic Fusarium strains, and naturally contaminated corn. A good correlation exists between IC50 and the T-2 toxin concentration as determined by GC analysis. The response is not affected by the presence of zearalenone or by small amounts of deoxynivalenol. A quantitative evaluation of cytotoxic trichothecenes in corn is valuable in the range of 100 ppb to 10 ppm, expressed as T-2 toxin equivalents. The result is obtained in 48 h
Liquid Chromatographic Determination of Amprolium in Poultry Feed and Premixes Using
Postcolumn Chemistry with Fluorometric Detection
Authors: Vanderslice Joseph T , Huang Mei-Hsia A
Published: February 2020

Two extraction and liquid chromatographic procedures are presented which separate amprolium from compounds in poultry feed or premixes that could interfere with its fluorometric determination. The procedures are based on earlier work on the determination of thiamine in food samples. Amprolium is extracted from feed with a hexane- aqueous sulfosalicylic acid mix, separated on a C18 column, and detected fluorometrically after postcolumn derivatization. For premixes, water extraction is used. Values for the amprolium content of poultry feed obtained with these procedures are in good agreement with those obtained with AOAC official methods. It is suggested that these methods with suitable modifications may be of use for routine analysis of amprolium in feeds. The overall methods are rapid and appear to give reasonable results
Simple Method for Distinguishing Maneb, Zineb, Mancozeb, and Selected Mixtures
Authors: Afsar HüYSEYIN , Demirata Birsen
Published: February 2020

Maneb, zineb, mancozeb, and arbitrarily selected mixtures of those can be differentiated by a simple method. Compounds are differentiated on the basis of colors produced after treatment of saturated solutions ofthe fungicides in n-propanol-acetone mixture (1 + 1 v/v), first with dithizone and then with monosodium dihydrogen phosphate solution in the same solvent. The color depends on the type and concentration of metal present in the sample
Chloride Determination in Foods with Ion-Selective Electrode After Isolation as Hydrogen
Chloride
Authors: Cerklewski Florian L , Ridlington James W
Published: February 2020

This report describes a sample preparation method in which chloride is isolated as hydrogen chloride from food samples prior to analysis with the chloride ion-selective electrode. Chloride analyses of selected foods with this method agreed with chloride values reported in food composition tables. Chloride analysis with the present procedure also agreed with the certified value for the chloride content of the National Bureau of Standards (NBS) Standard Reference Material, Nonfat Milk Powder. Reliability of the chloride isolation procedure was evident by the complete recovery of chloride added to food samples and a narrow range of 95% confidence limits calculated for each set of analyses. The usefulness of the chloride ion-selective electrode to determine chloride in foods is greatly enhanced by this procedure because matrix interference by other sample components is removed prior to analysis
Gas Chromatographic Determination of Alachlor in Microencapsulated Formulations: Mini-Collaborative Study
Authors: Tomkins David F
Published: February 2020

An isothermal gas chromatographic method for measuring alachlor in Micro-Tech® (microencapsulated) formulations was tested by 5 collaborators. The samples were prepared in acetone, and alachlor was determined using a gas chromatographic column of 10% SP- 2250 on 100-120 mesh Supelcoport. Di-n-pentylphthalate was used as the internal standard. Collaborators made single determinations on 5 samples distributed as blind duplicates. The mini-collaborative study generated 47 data points. The coefficient of variation (CV„- pooled) was 1.35%, and CVx-pooled was 0.73%. The method was simple to use and did not reveal any interferences in samples tested. The method has been adopted official first action as an AOACCIPAC method.
Spectrometric and Liquid Chromatographic Determination of Natamycin in Cheese and
Cheese Rind
Authors: Deruig Willem G , Van Oostrom Jacobus J , Leenheer Koos
Published: February 2020

Methods for determining natamycin content of cheese rind and cheese are presented. Cheese and rind samples are extracted with methanol and the fat precipitated by cooling the sample solution in methanolwater at -15 to -20°C for ca 1 h. Natamycin levels are measured by UV spectrometric detection at absorbance minimum 311 nm, maximum 317 nm, and at exactly 329 nm, or by LC separation over Lichrosorb RP-8 column with detection at 303 nm. For measuring low levels, a concentration step is provided. The method is applicable to natamycin in cheese rind and in the interior of the cheese. Detection limit is 0.5 mg/kg. The method is suitable for controlling a maximum tolerance of natamycin on the cheese rind, at a level of 1 mg/dm2, and for detecting migration of natamycin into the cheese.
Determination of Natamycin in Cheese and Cheese Rind: Interlaboratory Collaborative Study
Authors: Deruig Willem G
Published: February 2020

A collaborative test on the determination of natamycin in cheese and cheese rind was conducted. Participants were from 37 laboratories in 13 countries. Eight samples, consisting of 4 duplicates, were investigated by a spectrometric method and a liquid chromatographic (LC) method. The spectrometric method gave good results (coefficient of variation [CV] = 12%) and the LC method with ultraviolet detection gave reasonable results (CV = 25%) for levels down to 15 mg/ kg (0.9 mg/dm2). For very low levels, a preconcentration step is necessary, but even then quantitation is poor (CV = 35-37%) for both methods at 1.7 mg/kg, although the presence of natamycin can be detected qualitatively. For a level of 0.3 mg/kg, quantitation is poor (CV = 39%) for the LC method and impossible (CV = 60%) for the spectrometric method.
Validation of HPLC Method for Determination of Histamine in Human Immunoglobulin Formulations
Authors: Tanio Michikazu , Nakamura Toru , Kusunoki Hideki , Ideguchi Kyohei , Nakashima Kazuyuki , Hamaguchi Isao
Published: February 2020

Background

Histamine fixed-immunoglobulin formulations, which consisted of 0.15 µg of histamine dihydrochloride and 12 mg of human immunoglobulin in a vial, are used for anti-allergic treatments, and controlling the amounts of histamine in the formulations is essential to avoid histamine intoxication.

Objective

A high-performance liquid chromatography (HPLC) method for determination of histamine contents of the formulations was established and validated.

Methods

Histamine extracted from the formulation was labeled with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate and was analyzed by gradient elution HPLC with UV detection at 260 nm.

Results

The method showed linearity in the range 0.8–2.4 µM (R > 0.999), accuracy (100.1–105.8% recovery), and precision (relative standard deviation ≤ 1.93%). The validated method was applied for five lots of the pharmaceutical, and their histamine contents were determined to be 0.149–0.155 µg/vial.

Conclusions

These results indicated that the validated method is useful to control amounts of histamine in biopharmaceutical products.

Highlights

The HPLC method was developed for quantitative determination of histamine content of the histamine fixed-immunoglobulin formulations.
Squat and gait biomechanics 6 months following hip arthroscopy for femoroacetabular impingement syndrome
Authors: Cvetanovich Gregory L , Farkas Gary J , Beck Edward C , Malloy Philip , Jan Kyleen , Espinoza-Orias Alejandro , Nho Shane J
Published: February 2020

The purpose of this study was to (i) assess whether squat and gait biomechanical measures improve in patients with femoroacetabular impingement syndrome (FAIS) 6 months after surgery compared to pre-operative measures and (ii) compare biomechanical properties to controls without FAIS. In this prospective study, biomechanical data during a double leg squat task and gait for 15 FAIS patients and 9 controls were collected using three-dimensional motion analysis. Data were collected in the FAIS group at two-time points, pre-operatively and 6-month post-operatively following arthroscopic hip surgery, and at a single time point for the healthy controls. Independent sample’s t-test were used to compare the FAIS group to the controls, and paired samples t-test were used to determine within-group differences before and after hip arthroscopy in the FAIS group. The results indicated that there were significant within-group increases for sagittal plane moment rate during the double leg squat task (P = 0.009) between the pre-operative and post-operative time points for the FAIS group. Between-group differences showed that FAIS patients pre-operatively exhibit slower squat velocities during the descent (P = 0.005) and ascent phase (P = 0.012) of a double leg squat when compared healthy controls. Reduced hip external rotation moments during gait (P = 0.02) were also found between FAIS patients pre-operatively and controls. In conclusion, alterations in hip biomechanics are present before surgery for FAIS when compared to healthy controls, and joint mechanics change 6 months after surgery. However, the biomechanical differences during a double leg squat and gait were minimal.
TERT Promoter Mutation Analysis to Distinguish Glioma From Gliosis
Authors: Hewer Ekkehard , Phour Jaison , Gutt-Will Marielena , Schucht Philippe , Dettmer Matthias S , Vassella Erik
Published: February 2020

Among the most challenging diagnostic issues in surgical neuropathology is the distinction between scant infiltration by diffuse gliomas and reactive gliosis. The best documented ancillary marker to establish a definitive diagnosis of glioma in this setting is the identification of hotspot mutations in the isocitrate dehydrogenase 1 and 2 (IDH1/IDH2) genes, which is limited, however, by the low prevalence of these mutations in gliomas of elderly adults. Since telomerase reverse transcriptase (TERT) promoter mutations are present in the vast majority of IDH-wildtype diffuse gliomas, we hypothesized that combined analysis of IDH and TERT might overcome these limitations. For this purpose, we analyzed a series of non-neoplastic and neoplastic CNS samples for the prevalence of TERT hotspot mutations. TERT mutations were identified in none out of 58 (0%) reactive gliosis samples, and in 91 out of 117 (78%) IDH-wildtype gliomas. Based on a series of 200 consecutive diffuse gliomas, we found that IDH mutation analysis alone had a sensitivity of 28% (63% and 12%, respectively, in patients below and above age of 50) for detection of gliomas, whereas a combined analysis of IDH and TERT was 85% sensitive (87% and 84%, respectively, below and above age of 50). In sum, our findings suggest that TERT promoter mutation analysis contributes favorably to a molecular panel in cases equivocal for glioma versus gliosis on morphological grounds, especially in patients above age of 50, in which IDH analysis alone performs poorly.
Traumatic arteriovenous fistula: a 25-year delay in presentation
Authors: Stathis Alexandra , Gan John
Published: February 2020

A 64-year-old lady presented with a 6-month history of worsening unilateral leg swelling, with an audible bruit of the popliteal artery. Arterial duplex ultrasound confirmed the presence of an arteriovenous fistula (AVF) between the posterior tibial artery and vein. Upon thorough history, it was discovered that the patient had sustained a stab wound to this region some 25 years prior. The fistula was successfully managed endovascularly by means of a covered stent. This case highlights an unusual delayed presentation of an AVF and demonstrates the effectiveness of endovascular treatment of this condition.
Translating the Eastside: Embodied Translation in Helena María Viramontes’s Their Dogs Came with Them
Authors: Martín Desirée A
Published: February 2020

“Translating the Eastside: Embodied Translation in Helena María Viramontes’s Their Dogs Came With Them” argues that translation—specifically embodied translation—is the central mode through which Chicanx bodies confront the painful condition of inhabiting the fragmented spaces and temporalities that simultaneously construct and exclude them. In Dogs, translation is above all a process of carrying across, transferring, expressing and contesting meaning from one place to another through the physicality of the body. Embodied translation does not solely carry across meaning across texts or languages, but is itself a source of new knowledge, including insofar as it refuses to transfer meaning through the body. However, embodied translation is only transformative as much as it disrupts the direct translation imposed by the state which contains and regulates Chicanx bodies.

Rather than straightforwardly carrying meaning across, embodied translation foregrounds excess and lack, seemingly producing too much or not enough translation to produce and transfer meaning. Excessive modes of embodied translation, such as repetition or recycling, and those that indicate a lack, such as silence or muteness, are practices of dissent that continually reference space and temporality while calling other kinds of translation into question. As such, embodied translation stands as an excessive, persistent site of resistance that places systemic pressure on dominant institutions, marked through the intersection between bodies, space and temporality. In the process, embodied translation calls both the present and presence of Chicanx peoples into being in the face of their erasure in spaces like East Los Angeles.
Interleukin-37b inhibits the growth of murine endometriosis-like lesions by regulating proliferation, invasion, angiogenesis and inflammation
Authors: He Yongpei , Xiong Ting , Guo Fang , Du Zhenzhen , Fan Yixian , Sun Huanhuan , Feng Zuohua , Zhang Guimei
Published: February 2020

Endometriosis is a gynecological disease with abnormal expression of interleukin (IL)-37 which can suppress inflammation and the immune system. Here we investigated the role of the IL-37b splice variant in endometriosis in vivo and in vitro. In a murine model of endometriosis, in vivo administration of IL-37b significantly inhibited the development of lesions judged by the number (P = 0.0213), size (P = 0.0130) and weight (P = 0.0152) of lesions. IL-37b had no effect on the early stage of lesion formation, however administration in the growth stage of lesions decreased the number (P = 0.0158), size (P = 0.0158) and weight (P = 0.0258) of lesions compared with PBS control, an effect that was not reversed by macrophage depletion. Expressions of inflammatory factors, matrix metalloproteinases and vascular endothelial growth factor-A mRNA/protein were significantly inhibited in ectopic lesions following IL-37b administration, and in uterine segments treated in vitro. In vitro treatment of uterine segments with IL-37b inhibited phosphorylation of Akt and Erk1/2 in uterine segments. Isolated mouse endometrial stromal treated with IL-37b and transfected with pIL-37b plasmid got suppressed cell proliferation, invasion, angiogenesis and the expression of inflammatory factors. In addition, transfection with pIL-37b significantly decreased the phosphorylation of Akt and Erk1/2. IL-37b also inhibited proliferation and the expression of inflammatory and angiogenesis factors in epithelial cell line RL95–2. These findings suggest that IL-37b may inhibit the growth of lesions by regulating proliferation, invasion, angiogenesis and inflammation through Akt and Erk1/2 signaling pathway.
History-dependent percolation on multiplex networks
Authors: Li Ming , Lü Linyuan , Deng Youjin , Hu Mao-Bin , Wang Hao , Medo Matúš , Stanley H Eugene
Published: February 2020

The structure of interconnected systems and its impact on the system dynamics is a much-studied cross-disciplinary topic. Although various critical phenomena have been found in different models, study of the connections between different percolation transitions is still lacking. Here we propose a unified framework to study the origins of the discontinuous transitions of the percolation process on interacting networks. The model evolves in generations with the result of the present percolation depending on the previous state, and thus is history-dependent. Both theoretical analysis and Monte Carlo simulations reveal that the nature of the transition remains the same at finite generations but exhibits an abrupt change for the infinite generation. We use brain functional correlation and morphological similarity data to show that our model also provides a general method to explore the network structure and can contribute to many practical applications, such as detecting the abnormal structures of human brain networks.
The Struggling Infectious Diseases Fellow: Remediation Challenges and Opportunities
Authors: Melia Michael T , Paez Armando , Reid Gail , Chirch Lisa M , Luther Vera P , Blackburn Brian G , Perez Federico , Abdoler Emily , Kaul Daniel R , Rehm Susan , Harik Nada , Barsoumian Alice , Person Anna K , Yun Heather , Beckham J David , Boruchoff Susan , Cariello Paloma F , Cutrell James B , Graber Christopher J , Lee Dong Heun , Maziarz Eileen , Paras Molly L , Razonable Raymund R , Ressner Roseanne , Chen Anne , Chow Brian , Escota Gerome , Herc Erica , Johnson Andrew , Maves Ryan C , Nnedu Obinna , Clauss Heather , Kulkarni Prathit , Pottinger Paul S , Serpa Jose A , Bhowmick Tanaya , Bittner Marvin , Wooten Darcy , Casanas Beata , Shnekendorf Rachel , Blumberg Emily A
Published: February 2020

Remediation of struggling learners is a challenge faced by all educators. In recognition of this reality, and in light of contemporary challenges facing infectious diseases (ID) fellowship program directors, the Infectious Diseases Society of America Training Program Directors’ Committee focused the 2018 National Fellowship Program Directors’ Meeting at IDWeek on “Remediation of the Struggling Fellow.” Small group discussions addressed 7 core topics, including feedback and evaluations, performance management and remediation, knowledge deficits, fellow well-being, efficiency and time management, teaching skills, and career development. This manuscript synthesizes those discussions around a competency-based framework to provide program directors and other educators with a roadmap for addressing common contemporary remediation challenges.