bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of Alkalinity and Acidity of Water by Conductometric Acid-Base Titration
Authors: Sekerka Ivan , Lechner Josef F 
Published: February 2020

Abstract
The alkalinity and acidity of water are parameters of great importance for studies of aquatic ecosystems. This paper describes the determination of total alkalinity by using acid-base titration with trichloroacetic acid solution as titrant. Total acidity is determined by titration with ammonium hydroxide solution. Both titrations are monitored conductometrically. Performance is evaluated and compared with performance of the potentiometric titration. Automated conductometric titration is simple, fast (30 s/titration), sensitive (detection limit 0.1 ppm CaC03), and accurate. Relative error of the determination increased from about 1% at high levels to about 10% at 1 ppm CaC03. The relative standard deviation of alkalinity measurements ranged from to 5%; for acidity, these values ranged from 1.5 to 17%. Relative standard deviation reached 33% at lower detection limits. Samples containing noncarbonate contributory components of alkalinity (borate, silicate, phosphate, organic acids) can be reproducibly analyzed.
Determination of Captan, Folpet, and Captafol in Fruits and Vegetables, Using Two Multiresidue Methods
Authors: Gilvydis Dalia M , Walters Stephen M 
Published: February 2020

Abstract
Two multiresidue methods, the Mills method and the Luke et al. method, are widely used for the determination of pesticides in foods. These methods were evaluated for the determination of the fungicides captan, folpet, and captafol in selected fruits and vegetables. The analytical behavior of standards through these methods was investigated first. Recoveries from apples, strawberries, lettuce, and tomatoes fortified with these compounds at levels of 0.2-5.9 ppm were then obtained. The analytes were quantitated by gas chromatography with electron capture detection, using a column of 5% SP-2401 on 100-120 mesh Supelcoport. Recoveries of captan, folpet, and captafol from fortified crops ranged from 69 to 78, 90 to 93, and 67 to 83%, respectively, by the Mills procedure and from 87 to 102, 81 to 106, and 91 to 109%, respectively, by the Luke et al. method modified to include additional solvent elution of the optional Florisil column.
Improved Cleanup for Liquid Chromatographic Analysis and Fluorescence Detection of Aflatoxins M1 and M2 in Fluid Milk Products
Authors: Ferguson-Foos Jane , Warren J D 
Published: February 2020

Abstract
A rapid method is described for extraction and cleanup of raw and processed milk for determination of anatoxins M1 and M2 by using a C18 Sep-Pak/silica gel cleanup column combination. Anatoxins are separated by normal phase liquid chromatography and their concentrations are determined by fluorescence detection in a silica gel-packed flow cell. Recoveries ranged from 99 to 103% with coefficients of variation less than 2% for Mi levels of 0.117-1.17 ng/mL added to raw milk. Similar recoveries were obtained for M2. The coefficient of variation for analysis of 5 subsamples of naturally contaminated milk was Jess than 1%. Agreement with the official method is satisfactory. Each sample requires less than 25 mL solvent and 10 min actual handling time. Sample chromatograms show no interferences in the M1-M2 elution region and no late-eluting peaks, which permits spacing injections at 13-20 min intervals. Anatoxin levels as low as 0.03 ppb may be determined by this procedure. Extracts have also been analyzed by thin layer chromatography.
Liquid Chromatographic Determination of Nicarbazin in Feeds and Premixes
Authors: Macy Thomas D , Loh Andrew 
Published: February 2020

Abstract
A liquid chromatographic (LC) method has been developed for the determination of nicarbazin in premixes and poultry feed. Liquid chromatography of the 4,4'-dinitrocarbanilide (DNC) portion of nicarbazin is performed isocratically with a reverse phase octadecylsilica column and a UV detector set at 340 nm. The 2-hydroxy-4,6-dimethylpyrimidine (HDP) portion of nicarbazin is chromatographed isocratically with a reverse phase octylsilica column and a UV detector set at 305 nm. Nicarbazin concentration can be calculated by assaying both DNC and HDP, or by assaying DNC or HDP and assuming that nicarbazin is a 1:1 molar ratio of the two. Average recoveries of DNC and HDP added to poultry feed were 101% and 87%, respectively. This procedure provides an alternative to existing colorimetric procedures for determining nicarbazin in premixes and poultry feeds.
Liquid Chromatographic Determination of Methyldopa and Methyldopa-Thiazide Combinations in Tablets: Collaborative Study
Authors: Susan Ting ,   Collaborators:, Brown R L , Dougherty L A , Schepman J B , Doucette Y H , Schneider P J , Perry P J , Rihbany L A , Gordon K 
Published: February 2020

Abstract
A reverse phase liquid chromatographic method for the determination of methyldopa, methyldopa-hydrochlorothiazide, and methyldopachlorothiazide in tablets was collaboratively studied by 8 laboratories. Each collaborator received 20 samples that included drug substance, synthetic and commercial tablet compositions. The overall repeatability and reproducibility standard deviations for commercial tablets were 1.11 and 1.75% for methyldopa, 0.96 and 1.62% for chlorothiazide, and 1.21 and 2.15% for hydrochlorothiazide, respectively. The overall recoveries of methyldopa, chlorothiazide, and hydrochlorothiazide added to synthetic tablets were 100.78, 100.70, and 101.34%, respectively. The method has been adopted official first action.
Gas Chromatographic Determination of Nonvolatile Organic Acids in Sap of Sugar Maple (Acer saccharum Marsh.)
Authors: Mollica Joseph N , Morselli Maria Franca 
Published: February 2020

Abstract
Qualitative analysis of organic acids has never been reported for sugar maple sap, but only for its products, "sugar sand" and maple syrup. A gas chromatographic (GC) method is described for the simultaneous determination of up to 13 nonvolatile organic acids in sugar maple sap. Sap is filtered through Celite, and acids are isolated via cation- and anion-exchange chromatography. Reaction of dried acids with BSA [N,O-bis(trimethylsilyl)acetamide] in the presence of pyridine and methoxyamine hydrochloride yields the more volatile TMS (trimethylsilyl) esters. Oxalic, succinic, fumaric, L-malic, tartaric, cis-aconitic, citric, and/or shikimic acids were found in maple sap at concentrations ranging from less than 50 ppb to more than 45 ppm, depending on the particular acid and the date of sap flow. Percent recoveries and coefficients of variation for the acids at the 500 ppm level were 46.0 (3.2), 92.0 (2.9), 73.0 (0.77), 94.0 (2.0), 95.0 (−), 72.0 (−), and 97.0 (0.38), respectively. Various amounts of nonvolatile organic acids are reported in the sap of one sugar maple tree throughout a sap season, and of 3 individual maples during an early sap flow. Quantitation limits were as low as 15 ppb for individual acids in the analysis of a 100 mL sap sample. Esters were separated on a mixed liquid phase column of 4% SE-52/2% SE-30 on Chromosorb W-HP. They were identified by relative retention time, using a dual flame ionization detector. Naphthalene was used as the internal standard. Concurrent identification of pyruvic, malonic, glutaric, α-ketoglutaric, cis-aconitic, and isocitric acids with those previously mentioned is also possible.
Liquid Chromatographic Determination of Tetracycline Residues in Meat and Fish
Authors: Onji Yoshiki , Uno Masakiyo , Kaoru Tanigawa 
Published: February 2020

Abstract
A simple and rapid method was developed for quantitative determination of common tetracyclines, such as oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC), in meat and fish. Tetracyclines were extracted with aqueous HCI, and then centrifuged. The supernate was applied to an Amberlite XAD-2 column, which was washed with water and eluted with methanol. The eluate was concentrated to about 0.5 mL under vacuum at 35°C, and then measured by liquid chromatography and UV detection. Two analytical columns were used for confirmation. The average recoveries of OTC, TC, and CTC from meat and fish fortified at 1, 1, and 3 ppm were 82.6, 81.5, and 67.0% respectively.
Determination of Aflatoxins in Vegetable Oils
Authors: Miller Noah , Pretorius Helena E , Trinder Donald W 
Published: February 2020

Abstract
A simple method is proposed for determination of aflatoxins in vegetable oils. The method was successfully applied to both crude and degummed oils. The oil sample, dissolved in hexane, was applied to a silica column and washed with ether, toluene, and chloroform; aflatoxins were eluted from the column with chloroform-methanol (97 + 3). As quantitated by thin layer chromatography and liquid chromatography, the oils analyzed contained aflatoxin Bx at levels of 5-200 αg/kg. Recoveries of aflatoxin Bi standards added to aflatoxin-free oils were between 89.5 and 93.5%, with coefficients of variation of 6.3- 8.0%.
Detection and Determination of Error in Analytical Methodology Part IIB. Direct Calculational Technique for Making Corrigible Systematic Error Corrections
Authors: Cardone Mario J , Lehman Jay G 
Published: February 2020

Abstract
The direct calculational technique described allows extrapolation to an infinite-size sample. The relationship between conventional calibration curve-based concentration values and reciprocal sample weights over the linear dynamic range of interest is obtained by linear regression. The intercept is shown to be the concentration result for the sample which has been corrected for the systematic corrigible constant error bias. In an analogous procedure described, the concentration result, corrected for both the corrigible systematic bias proportional and constant errors, may also be directly determined. The theoretical basis of the fundamental relationship is presented as well as theoretical derivations for the conventional calculation in calibration curve-based analyses and for the calculation used in the method of standard additions
Gas Chromatographic Determination of Ethylene Dibromide in Flour Products
Authors: Mckay Gordon 
Published: February 2020

Abstract
A method based on gas chromatography with electron capture detection was developed for the determination of ethylene dibromide (EDB) extracted from flour products. The procedure relies on the organic extraction of flour/water mixtures and uses an internal standard, 1- bromo-3-chloropropane. Recoveries of EDB at 10 and 100 ppb were 80.1 ± 2.8% (SD) and 84.4 ± 4.3%, respectively; recovery of the internal standard at the working concentration 500 ppb was 98.3 ± 6.7%. Calibration curves were linear over the range 5-400 ppb, with a mean overall coefficient of variation of &lt;5%. The reliability of the procedure was assessed by using gas chromatography combined with mass spectrometry. Results are shown for determination of EDB in locally milled flour products.
Fractionation Of Radioactivity In The Milk Of Goats Administered 14c-Aflatoxin B1
Authors: Goto Tetsuhisa , Hsieh Dennis P H 
Published: February 2020

Abstract
A detailed fractionation of radioactivity in the milk of goats administered 14C-aflatoxin Bx at low doses was performed. The milk collected in the first 24 h following dosing contained radioactivity equivalent to 0.45-1.1% of the dose given. The radioactivity in each sample was partitioned into 4 fractions: ether, protein, dichloromethane, and wateralcohol. Over 80% of the radioactivity was detected in the dichloromethane fraction, of which over 95% was attributable to aflatoxin M1. No aflatoxin B, or other known aflatoxin metabolites were detected in any fraction. The results indicate that the major metabolite of aflatoxin B, in goat milk is aflatoxin M] and that other metabolites, including conjugates, are of minor significance.
Rapid Gas Chromatographic Determination of Ethylene Oxide, Ethylene Chlorohydrin, and Ethylene Glycol Residues in Rubber Catheters
Authors: Muzeni Richard J 
Published: February 2020

Abstract
Isothermal gas chromatography with flame ionization detection was used to determine residual ethylene oxide (EtO), ethylene chlorohydrin, and ethylene glycol in soft rubber catheters that had been sterilized with EtO. Catheter samples were extracted by shaking with carbon disulflde, and the extract was analyzed on a 3% Carbowax 20M on 80- 100 mesh Chromosorb 101 column, using nitrogen as the carrier gas. Ten replicate injections of a mixed standards solution gave coefficients of variation of 1.91, 1.23, and 4.74% for EtO, ethylene chlorohydrin, and ethylene glycol, respectively. A linear response was obtained with concentrations ranging from 1.0 to 7.9 μg EtO, 14.0 to 88.0 μg ethylene chlorohydrin, and 31.0 to 98.5 μg ethylene glycol. The proposed method detected as little as 0.5, 5.0, and 16.5 ng EtO, ethylene chlorohydrin, and ethylene glycol, respectively.
Rapid Hydrophobic Grid Membrane Filter Method for Salmonella Detection in Selected Foods: Collaborative Study
Authors: Entis Phyllis 
Published: February 2020

Abstract
A collaborative study was carried out in 36 laboratories to validate a hydrophobic grid membrane filter method for rapid (2-3 days) Salmonella detection by comparing its performance against the AOAC/ BAM reference method. Six products were included in the study: semisweet chocolate, raw ground poultry meat, ground black pepper, cheese powder, egg powder, and nonfat dry milk. With the exception of the naturally contaminated poultry, all products were inoculated in advance with low concentrations of a variety of Salmonella serotypes. The hydrophobic grid membrane filter method detected the following numbers of positive samples (results of the AOAC/BAM reference method are shown in parentheses): chocolate, 67(68); raw ground poultry, 133(131); ground black pepper, 57(56); cheese powder, 81(80); egg powder, 51(45); and nonfat dry milk, 68(72). The 2 methods did not differ significantly at the 95% confidence level in any of the 6 foods. The hydrophobic grid membrane filter method has been adopted official first action for detection of Salmonella in selected foods.
Improved Procedure for Determination of Acrylonitrile in Foods and Its Application to Meat
Authors: Page Denis B , Charbonneau Claudette F 
Published: February 2020

Abstract
The previously described headspace-gas chromatographic procedure for the determination of acrylonitrile (AN) in several foods, with N/P selective detection, has been modified to include packaged luncheon meats. The loss of AN during equilibration at 100°C in meat samples as well as the previously described loss in cold pack cheese and peanut butter has been studied. The loss of AN could be prevented by the addition of 10% phosphoric acid, which increases the acidity of the food-acid-salt slurry to pH 1.2-1.5. This acidification permits detection of AN at 2 ppb (5% FSD at 16 x 102 amp/mV) in all foods studied. AN was not detected in 10 samples of luncheon meat packaged in AN-based plastic which contained up to 2.6 ppm AN.
Liquid Chromatographic Determination of Vitamin K1 Trans- and Cis-Isomers in Infant Formula
Authors: Hwang Shie-Ming 
Published: February 2020

Abstract
The normal phase liquid chromatographic (LC) method for determination of trans- and c/s-isomers of vitamin K1 (phylloquinone) in infant formula described here uses an Apex silica column, isocratic elution, and UV absorption detection at 254 nm. Vitamin Kt is extracted quantitatively from the product matrix by pretreating the as-fed liquid with concentrated ammonium hydroxide and methanol, and then extracting it with a 2:1 mixture of dichloromethane and isooctane. The extract is cleaned up by silica open-column chromatography and concentrated for LC analysis. For trans-vitamin K1, the method precision is ≤3% RSD (relative standard deviation), and the spike recovery is 98 ± 4%. For cis-vitamin K1,, the precision is &lt;12% RSD, determined at levels near the detection limit, and the spike recovery is 95 ± 9%. The detection limit is 0.3 ng for both isomers at signal/noise = 3.
Liquid Chromatographic Determination of N-Methylcarbamate Insecticides and Metabolites in Crops. I. Collaborative Study
Authors: Krause Richard T 
Published: February 2020

Abstract
A liquid chromatographic (LC) multiresidue method for determining residues of iV-methylcarbamate insecticides in crops was collaboratively studied in 6 laboratories. Methanol and a mechanical ultrasonic homogenizer are used to extract the carbamates. Water-soluble plant coextractives and nonpolar plant lipid materials are removed from the carbamate residues by liquid-liquid partitioning. Additional crop coextractives (e.g., carotenes, chlorophylls) are removed with a Nuchar SN-silanized Celite column. The carbamate residues are then separated on a reverse phase LC column, using an acetonitrile-water gradient mobile phase. Eluted residues are detected by an in-line post-column fluorometric detection technique. Seven carbamates and 2 carbamate metabolites were included in the collaborative study. Each collaborator determined all the carbamates at 2 levels (approximately 0.05 ppm and United States tolerance) in blind duplicate samples of grapes and potatoes. Fortified and control samples were analyzed. Repeatability coefficients of variation for all the carbamates on the 2 crops averaged 4.7% and ranged from 2.4 to 7.1%. Reproducibility coefficients of variation for all the carbamates on the 2 crops averaged 8.7% and ranged from 5.3 to 12.4%. Accuracy, measured by comparison with fortification values, averaged 95% and ranged from 79 to 103%. The estimated limit of quantitation is 0.01 ppm. The method has been adopted official first action.
Liquid Chromatographic Determination of N-Methylcarbamate Insecticides and Metabolites in Crops. II. Analytical Characteristics and Residue Findings
Authors: Krause Richard T 
Published: February 2020

Abstract
Four laboratories obtained 177 carbamate recovery values using a liquid chromatographic method. The average recovery of 11 carbamates (aldicarb, aldicarb sulfone, bufencarb, carbaryl, carbofuran, 3- hydroxy carbofuran, 3-keto carbofuran, methiocarb, methiocarb sulfoxide, methomy 1, and oxamyl) from 14 crops was 99% with a coefficient of variation of 8% (0.03-1.8 ppm fortification levels). No statistical difference in recovery was found between oxime and phenyl carbamates, or between parent and metabolite carbamates. Average recovery of aldicarb sulfoxide was 59% due to loss in the liquid-liquid partitioning because of the polarity of this compound. A fifth laboratory contributed 34 carbamate recoveries (average 99%) on table-ready food products for 4 carbamates. Bendiocarb, dioxacarb, isoprocarb, and propoxur are also quantitatively recovered through the method. Previously reported carbamate and noncarbamate recovery data are also discussed. In the Food and Drug Administration's (FDA) analysis of 319 samples (mainly crops), 86 (27%) were found to contain residues of carbamate insecticides and/or toxic carbamate metabolites. Carbaryl and methomyl were the most common carbamate residues found on the food products excluding the aldicarb sulfone and sulfoxide residues found on potatoes. In one FDA Total Diet Program "market basket", 11 of 69 table-ready food commodities contained from 0.005 to 0.094 ppm carbamate residues. Carbaryl was the most prevalent residue. Several laboratories reported adverse effects on the determinative system when inadequately purified reagents were used.
Use of Microwave Oven and Nitric Acid-Hydrogen Peroxide Digestion to Prepare Botanical Materials for Elemental Analysis by Inductively Coupled Argon Plasma Emission Spectroscopy
Authors: White Thomas R , Douthit Garnett E 
Published: February 2020

Abstract
A sample preparation method has been developed that provides a nitric acid-hydrogen peroxide digestion of plant tissue when it is heated internally by the oscillating electromagnetic field generated in a microwave oven. The total elemental concentration for barium, calcium, magnesium, manganese, phosphorus, potassium, sodium, sulfur, and zinc can be determined by inductively coupled argon plasma emission spectroscopy after sample preparation in a microwave oven. The method is rapid and provides quantitative results that agree with certified values for 4 National Bureau of Standards Standard Reference Materials: 1570 Spinach, 1572 Citrus Leaves, 1573 Tomato Leaves, and 1575 Pine Needles.
Identification and Quantitation of Sulfamethazine Metabolites by Liquid Chromatography and Gas Chromatography-Mass Spectrometry
Authors: Paulson Gaylord D , Mitchell Alva D , Zaylskie Richard G 
Published: February 2020

Abstract
Methods for the identification and quantitation of carbon-14 labeled sulfamethazine [4-amino-iV-(4,6-dimethyl-2-pyrimidinyl)benzenesulfonamide], W-acetylsulfamethazine, the N4-glucose conjugate of sulfamethazine, and desaminosulfamethazine in swine tissue are described. Tissues are ground and extracted with methanol, and the 14C-labeled compounds are purified by XAD-2 column chromatography and C-18 reverse phase liquid chromatography (LC) and the relabeled compounds are then methylated and identified by gas chromatography- mass spectrometry analysis. Quantitation is accomplished by measuring the amount of 14C-activity that cochromatographs (C-18 reverse phase LC) with reference compounds.
Antibiotic Identification by High Voltage Electrophoresis Bioautography
Authors: Lott Anthony F , Smither Roy , Vaughan David R 
Published: February 2020

Abstract
The high voltage electrophoresis bioautography method is applicable to meat, milk, and animal feeds. Meat is freeze-dried, powdered, and extracted with acetonitrile-water (9 + 1), and the extract is concentrated by evaporation at room temperature. Milk is examined directly or following acetonitrile-water extraction. Feed is extracted with acetonitrile- water. Samples or extracts are applied to preliminary assay plates of antibiotic medium No. 1 at pH 6 and 8, seeded with Micrococcus luteus (ATCC 9341), M. luteus DHSR (ATCC 9341A), Bacillus cereus (ATCC 11778), or B. cereus K250 TR (NCIB 11183), and nutrient agar at pH 7 seeded with B. subtilis BGA. Inactivation of penicillinase indicates beta-Iactam antibiotics. Addition of trimethoprim increases sensitivity to sulfonamides. After 18-24 h incubation at 30°C, plates yielding clear inhibition zones guide selection of conditions for subsequent electrophoresis bioautography. Extracts are applied (5-100 |xL) to 10 mm diameter wells on electrophoresis plates 60 cm long and 40 cm wide, with a gel depth of 1.6 mm. The support medium is 1% agar and 1 % agarose in Tris/succinic acid buffers pH 6 and pH 8. A potential of 1500 V is applied for 1.5 h at 15°C. Following electrophoresis, the migrated antibiotics are visualized by over-layering with antibiotic medium No. 1, pH 6 or 8, seeded with M. luteus or B. cereus spore suspension; plates are incubated for 18-24 h at 30°C. Identification is based on results of preliminary screening together with electrophoretic migration distances and inhibition zone appearances compared with standards
Microbiological Assay for Chloramphenicol Residues
Authors: Singer Carol J , Katz Stanley E 
Published: February 2020

Abstract
Procedures for the assay of chloramphenicol in milk, urine, serum, and muscle tissue are presented. The procedures specify an assay design with all standards as well as samples present on each plate, oxytetracycline in the buffer-diluent for greater sensitivity, a minimal medium to enhance the inhibitory effect of chloramphenicol on the assay organism, and a tetrazolium dye to improve the ability to measure the zones of inhibition. Recoveries of unbound chloramphenicol from bovine urine were 90.8%, from serum 88.3%, from milk 79.3%, from swine muscle 71.3%, and from beef and chicken muscle 61.0 and 61.4%, respectively. The lower levels of measurement in urine and serum were 0.25 ug/mL, 0.025 n-g/mL in milk, and 0.10 |xg/g in muscle tissue