bluuebunny/crossref_metadata_2025_split huggingface dataset:
Passive Diffusion through Polymeric Membranes: A Novel Cleanup Procedure for Analysis of Azinphos-Methyl and Azinphos-Ethyl Residues in Fruits and Vegetables
Authors: Ahmad Nazir , Guo Lin , Mandarakas Peter , Appleby Sbmeone , Bugueno George 
Published: February 2020

Abstract
A novel procedure is described for simple removal of coextractives prior to analysis of fruits and vegetables for azinphos-methyl and azinphos-ethyl residues. The solvent extract is concentrated, placed in a polymeric membrane tube, and then dialyzed in cyclohexane. Both azinphos-methyl and azinphos- ethyl diffuse into the surrounding solvent while coextractants remain inside the membrane. The dialyzing solvent is exchanged during concentration with n-hexane and analyzed without further cleanup by gas-liquid chromatography with a specific thermionic detector. The detection limit for a 25 g grape sample with final volume of extract made to 15 mL was 0.01 mg/kg. Recoveries of both residues from grapes averaged 107% (spike levels of 0.3 to 2.0 mg/kg). From a 20 g spinach sample, recoveries averaged 82% for azinphos-methyl and 72% for azinphos-ethyl when final volume of extract was made to 5 mL (spike levels of 0.1 to 1.0 mg/kg). Recoveries from 20 types of fruits and vegetables (20 g sample spiked at 1 mg/kg for both azinphos-methyl and azinphos-ethyl) were consistently greater than 70%, except for strawberries (61–67%) and avocado (28–34%). The high lipid content of avocado may impede diffusion of azinphosmethyl and azinphos-ethyl through the polymeric membrane. A field evaluation of the procedure showed a strong correlation (r = 0.957) between azinphos-methyl residues on grapes and treatments with 2 spray formulations. The membrane cleanup procedure is a simple and cost-effective alternative to other column or liquid–liquid partitioning procedures for azinphos-methyl and azinphosethyl residue analysis.
Modification of AOAC Multiresidue Method for Determination of Synthetic Pyrethroid Residues in Fruits, Vegetables, and Grains. Part II: Acetone Extraction System
Authors: Pang Guo-Fang , Chao Yan-Zhong , Fan Chun-Lin , Zhang Jin-Jie , Li Xue-Min , Liu Yong Ming , Zhao Tee-Sheng 
Published: February 2020

Abstract
To optimize conditions and to evaluate further a multiresidue method for pyrethroids, various extraction solvents and partitioning conditions were examined. Acetone and acetonitrile (for fruits and vegetables) and acetone–water and acetonitrile–water (for grains) were used as solvents with or without acetonitrile partitioning. Twenty crops fortified with 8 pyrethroid insecticides at low, medium, and high levels were analyzed. For limit of detection (LOD) levels, repeatability tests were completed with acetone–water as extraction solvent. Recoveries of 8 pyrethroid insecticides at LOD levels were 76.2–99.6%, with coefficients of variation (CVs) of 2.08–10.90% for narrow-bore capillary gas chromatography (GC) (n = 6) and 80.1–107.3% with CVs of 3.76–15.38% for wide-bore capillary GO (n = 6). Both acetone or acetone–water extraction with acetonitrile partitioning and acetonitrile or acetonitrile–water extraction with acetonitrile partitioning are suitable for multiresidue analysis of pyrethroid insecticides. However, acetonitrile and acetonitrile– water as extraction solvents were better than acetone and acetone–water at LOD-fortified levels. This finding was confirmed chromatographically with pear, cucumber, and barley control samples.
Rapid Determination of Neomycin by a Microbiological Agar Diffusion Assay Using Triphenyltetrazolium Chloride
Authors: Yamamoto Célia H , Pinto Terezinha J A 
Published: February 2020

Abstract
The standard, quantitative determination of neomycin activity by the agar diffusion method requires an 18 to 24 h incubation time. To reduce incubation time, an alternative method using triphenyltetra- zolium chloride has been developed. The inhibition zoneappears much earlier; hence, an effort was made to standardize it. This indicator develops a physical response, related to the biological one, after a determined period. A Staphylococcus epidermidis suspension inoculated into solid medium ata concentration low enough that growth is not visible can reduce the dye to formazan. There is enough contrast to read the inhibition zone optically after a7 h incubation. There is no significant difference between standard curves for 7 and 24 h incubations.Comparative assays for some pharmaceutical drugs containing neomycin in different forms show that it is possible to reduce incubation time. This modification is valid because no dispersion of results was detected by statistical analysis, which indicates that they belong to the same population. Thus, a rapid microbiological assay of neomycin has been validated and standardized
Use of Amino Acid Profiles of Pretermand Term Human Milks in Evaluating Scoring Patterns for Routine Protein Quality Assessment of Infant Formulas
Authors: Sarwar Ghulam , Darling Pauline , Ujiie Mariko , Botting Herbert G , Pencharz Paul B 
Published: February 2020

Abstract
Reports on the amino acid composition of human milk vary considerably with respect to concentrations of sulfur amino acids. Often, analyses forego tryptophan determination. A complete analysis of protein and amino acid concentrations was performed on human milk samples (5-10 days postpartum) collected from mothers of preterm (gestations of 25-32 weeks) and term (gestations of &gt;36 weeks) infants. Careful attention was given to quantitate amino acids such as cysteine and tryptophan, which are vulnerable to acidic hydrolysis conditions. Differences in concentrations of total amino acids (expressed on protein basis) between preterm and term milks were small, despite the higher true protein content of preterm milk versus term milk (19.20 versus 12.60 g/L). The methionine + cyst(e)ine contents of term and preterm milks (3.72-3.84 g/100 g protein) were comparable with those reported in 1991 by the Food and Agricultural Organization/World Health Organization (FAO/WHO) for mature human milk (4.20 g/100 g protein) but higher than those reported in 1991 by the European Commission (2.9 g/100 g protein).The amino acid pattern of human milk obtained in this study confirms that the 1991 FAO/WHO amino acid scoring pattern for predicting protein quality of infant formulas is representative of the amino acid quality of both preterm and term human milks.
Liquid Chromatographic Determination of Mebendazole and its Metabolites, Aminomebendazole and Hydroxymebendazole, in Eel Muscle Tissue
Authors: Hajee Christiaan A J , Haagsma Nel 
Published: February 2020

Abstract
An analytical method is presented for liquid chromatographic (LC) determination of mebendazole (MBZ), hydroxymebendazole (MBZ-OH), and aminomebendazole (MBZ-NH2) in eel muscle tissue. Muscle tissue is extracted with ethyl acetate at pH 7.5. After addition of n-hexane, the extract is cleaned up and concentrated on an aminopropyl solid-phase extraction column. The test solutions are analyzed isocratically on a ChromSpher B LC column with acetonitrile–phosphate buffer, pH 6.2, as mobile phase. Limits of detection and quantitation were 0.7 and 1.1 ¼g/kg, respectively, for MBZOH; 1.4 and 2.3 ¼g/kg, respectively, for MBZ; and 1.5 and 2.1 ¼g/kg, respectively, for MBZ-NH2. Interand intraday coefficients of variation were 3.5 and 3.4%, respectively, for MBZ-OH; 2.5 and 3.1%, respectively, for MBZ; and 5.8 and 4.8%, respectively, for MBZ-NH2. Mean recoveries were 90% for MBZ, 74% for MBZ-NH2, and 92% for MBZ-OH. A linear range of applicability of at least 10–1000 ¼g/kg was found for each analyte. Incurred MBZ-NH2 (181.3 ¼g/kg) was identified in eel muscle tissue apart from MBZ (23.7 ¼g/kg) after 48 h exposure ina treatment bath containing MBZ at 1 mg/L.
Determination of Fruit Juice Authenticity by Capillary Gas Chromatography with Flame Ionization Detection
Authors: Low Nicholas H 
Published: February 2020

Abstract
A method using capillary gas chromatography with flame ionization detection was developed to determine the addition of high�fructose syrup and beet or cane invert syrup to apple or orange juice. Fingerprint oligosaccharides in these inexpensive sweeteners were not detectable (area &lt; 1000) in pure apple or orange juice. One hundred twenty- three pure apple juice and 60 pure orange juice samples representing growing regions around the world were analyzed. Ten samples were intentionally adulterated with each sweetener at levels of 5, 10, and 15%. The detection limit for each sweetener was 5%.
Determination of Selenium in Urine by Hydride Generation Atomic Absorption Spectrometry
Authors: Navarro Miguel , Lopez Herminia , Lopez Maria C , Perez Vidal 
Published: February 2020

Abstract
A procedure has been developed for determination of total selenium in urine by hydride generation atomic absorption spectrometry. Mineralization was performed with a nitric acid–perchloric acid mixture on a thermostated digestion block. The method was validated by comparison with the method involving mineralization in a microwave acid digestion bomb containing nitric acid and small amounts of vanadium pentoxide. Se(VI) was reduced to Se(IV) by dissolution in 7N HCI. Sample recoveries, precision studies, and analyses of a certified reference material demonstrated the reliability and accuracy of this technique. Urine samples had selenium concentrations ranging from 4.6 to 50.3 μg/L. These values correspond to an average of 54.9 μg per person per day total ingested and bioavailable Se in the daily diet.
Determination of Bensulfuron Methyl in Rice and Crayfish by Liquid Chromatography with a Column- and Eluant-Switching System and UV Detection
Authors: Zhou In , Bramble Fred Q , Devine Tim J , Norwood Gwen I 
Published: February 2020

Abstract
Bensulfuron methyl (an active ingredient of Londax herbicide) was determined in rice and crayfish by liquid chromatography with column switching (LCCS), using a simple extraction and cleanup scheme. After bensulfuron methyl was extracted from sample with methylene chloride, the extract was concentrated, cleaned up, and reconstituted into acetonitrile–water (1+1, v/v). The extract was further cleaned up chromatographically, and then bensulfuron methyl was quantitatively determined by reversed-phase LC using a column- and eluantswitching system and UV detection at 254 nm. Bensulfuron methyl was recovered at 90 ± 8% over a range of 0.008 to 1.0 ppm from fortified samples of polished rice, rice grain, rice straw, rice hull, rice bran, aspirated grain fractions, and crayfish. Method quantitation limits were 0.008 ppm for polished rice and rice grain; 0.02 ppm for rice hull, rice bran, aspirated grain fractions, and crayfish; and0.05 ppm for rice straw.
Emergence of Rapid Methods for Identifying Microbial Pathogens in Foods
Authors: Feng Peter 
Published: February 2020

Abstract
Because of the complexities of food analysis, conventional microbiological methods must use timeconsuming enrichment steps for culturing viable bacterial cells in foods. With rapid advancements in technology, however, numerous so-called rapid methods were introduced into the field of food microbiology in a relatively short time. Culture methods that were once used to obtain profiles for bacterial identification were simplified or automated. Many microbiological procedures were also streamlined or automated to reduce assay time, labor, and materials. Nucleic acid-based assays are used to identify gene sequences in foodborne bacteria, and antibody-based assays are used in numerous formats to detect bacterial pathogens and toxins in foods. The difficulties of analyzing food, however, remain challenging, and rapid methods need to be evaluated thoroughly before they are used for routine food analysis.
Indirect Spectrophotometric Determination of Chromium
Authors: Balasubramanian N , Maheswari V 
Published: February 2020

Abstract
A sensitive spectrophotometric method for determining trace amounts of chromium(VI) is described. In the presence of acetate buffer, chromium(VI) oxidizes hydroxylamine quantitatively to nitrite at pH 4.0 ± 0.5. The nitrite diazotizes p-nitroaniline to form a diazonium salt that, in acidic medium, couples with N-(1-naphthyl)ethylenediamine dihydrochloride to form an azo dye with a molar absorptivity of 4.1 x 104 L/mol-cm at 545 nm. The color is stable for 5 h, and the system obeys Beer's law in the range 0-8 μg chromium(VI) in a final volume of 10 mL. The detection limit of chromium(VI) is 0.6 μg. Chromium(lll) can be determined after it is oxidized with bromine water in alkaline medium to chromium(VT). Extraction of the azo dye in alkaline medium with methyl isobutyl ketone followed by addition of methanolic hydrochloric acid permitted determination of chromium(VI) down to 10 ng/mL. The method has been used to determine chromium in alloy steels, pharmaceutical preparations, and industrial effluents.
Determination of Citrinin in Barley by Indirect and Direct Enzyme Immunoassay
Authors: Abramson David , Usleber Ewald , Martlbauer Erwin 
Published: February 2020

Abstract
Polyclonal antibodies against the mycotoxin citrinin were raised in rabbits after immunization with citrinin conjugated to keyhole limpet hemocyanin. The antibodies were used in a competitive indirect enzyme immunoassay (EIA) with citrinin coupled to glucose oxidase as the solid-phase antigen for coating microtiter plates. Detection limits of this indirect EIA for citrinin ranged from 0.4 to 0.8 ng/mL for buffer solutions. Recoveries of citrinin added to ground barley at 100–2000 ng/g ranged from 105 to 112%, with coefficients of variation between 4.5 and 12%. A direct competitive EIA also was established, with citrinin coupled to horseradish peroxidase as the labeled antigen. Detection limits of this direct EIA for citrinin ranged from 2 to 4 ng/mL for buffer solutions. Recoveries of citrinin added to ground barley at 500–2000 ng/g ranged from 108 to 111%, with coefficients of variation between 8.4 and 26.9%. In naturally contaminated barley samples assayed with the indirect EIA, optimum extraction of citrinin was obtained in 30 min, and only one extraction was necessary to recover 72–76% of the analyte.
Modification of AOAC Multiresidue Method for Determining Synthetic Pyrethroid Residues in Fruits, Vegetables, and Grains. Part III: Studies of Analyte Stability and Method Ruggedness
Authors: Pang Guo-Fang , Cao Yan-Zhong , Fan Chun-Lin , Zhang Jin-Jie , Li Xue-Min 
Published: February 2020

Abstract
The stability of 8 synthetic pyrethroids in 9 crops during storage for 90 days were studied. The 8 pyrethroid insecticides were highly persistent in the 6 grains during storage. But their stabilities in 3 kinds of fruits and vegetables were different from those in the 6 grains: Most of them were degraded. Florisil purification conditions were studied with 6 batches of Florisil from 3 countries at various extents of deactivation and amounts. The best conditions of Florisil purification found in this present research agree with those found 1 year ago. The efficiencies of acetonitrile and acetone to extract the 8 pyrethroids from 6 fruit and vegetable samples were compared. The extraction efficiency of acetone was competitive with that of acetonitrile for the 6 fruit and vegetable samples. Method performance was evaluated by 6 analysts from different areas. The ruggedness tests demonstrate further that the proposed method is simple, accurate with good precision, and suitable for multiresidue analysis of pyrethroids in various agriculture products.
Determination of Chlordane and Chlorpyrifos in Ambient Air at Low Nanogram-Per-Cubic Meter Levels by Supercritical Fluid Extraction
Authors: Swami Kamal , Narang Amarjit S , Narang Rajinder S 
Published: February 2020

Abstract
A method for the determination of termiticides present in ambient air was simplified by modifying the extraction thimbles used in the Hewlett-Packard supercritical fluid extractor so they could be used for collection as well as extraction of termiticides. The method was applied to the determination of chlorpyrifos and technical chlordane. The termiticides were trapped on cartridges containing Florisil and foam plugs, extracted with carbon dioxide in the supercritical fluid extractor, and determined by capillary gas chromatography with electron capture detection. On the basis of a 20 m3 sample, detection limits were 0.1 ng/m3 for chlorpyrifos and 1.0 ng/m3 for technical chlordane.
Fine Tuning a Bile-Enzymatic-Gravimetric Total Dietary Fiber Method
Authors: Cranker Kenneth J , Phillips Katherine M , Gonzales Maria Carmen Rita V , Stewart Kent K 
Published: February 2020

Abstract
A recently proposed bile-enzymatic-gravimetric total dietary fiber (TDF) method was modified and the new procedure was compared with the original method, the traditional AOAC enzymatic-gravimetric determination (AOAC Official Method 985.29), and another simplified AOAC procedure by analyzing several diet composites, including National Institute of Standards and Technology 1548 total diet reference material. The original and modified bile-enzymatic-gravimetric procedures also were compared by analyzing 9 food samples from a collaborative study of the original method. The modified method consistently yielded values about 10% lower than the original method but closer to reference values and to values from AOAC Offical Method 985.29, suggesting results that are more in line with accepted TDF standard methodology. Our modified method was used to analyze 180 fresh-frozen diet composites with TDF values ranging from 0.6 to 3.2 g/100 g wet weight. Samples were from 2 multicenter feeding studies sponsored by the National Heart, Lung and Blood Institute: DELTA (Dietary Effects on Lipoproteins and Thrombogenic Activity) and DASH (Dietary Approaches to Stop Hypertension). The mean relative standard deviation (RSD) for duplicate analyses was 1.1%. For 40 assays of a quality control diet composite over 9 months, the standard deviation was 0.1 g/100 g wet weight (4.9% RSD), indicating the method’s excellent precision for routine use.
Chiral Gas Chromatographic Determination of Ephedrine-Type Alkaloids in Dietary Supplements Containing Má Huáng
Authors: Betz Joseph M , Gay Martha L , Mossoba Magdi M , Adams Sarah , Portz Barbara S 
Published: February 2020

Abstract
Má Huáng is a traditional Chinese medicine derived from the aerial parts of several Ephedra species (Ephedraceae). These plants produce (–)-ephed- rine, (+)-pseudoephedrine, (–)-norephedrine, (+)- norpseudoephedrine, (–)-N-methylephedrine, and (+)-N-methylpseudoephedrine. Racemic and (–)- ephedrine, (+)-pseudoephedrine, and (±)-norephe- drine (phenylpropanolamine) are used clinically in the United States and are largely synthetic in origin. Current interest in Má Huáng is spurred by reports describing a “thermogenic” (calorie burning) effect provided by mixtures of ephedrine, caffeine, and aspirin. Products providing the key thermogenic compounds from natural sources are available as dietary supplements in retail outlets. Reports of potentially unsafe levels of the alkaloids, as well as possible fortification of Má Huáng-containing products with synthetic Ephedra alkaloids, prompted the development of a chiral gas chromatographic (GC) method that allows determination of alkaloid patterns and identification of isomerically impure synthetic alkaloids. Nine products were analyzed on a γ-cyclodextrin capillary GC column. Identity of the alkaloids was verified by GC/mass spectrometry (MS) and GC/matrix isolation/Fourier transform infrared spectroscopy. No synthetic isomers were found in the dietary supplements analyzed. Three products contained only one of the ephedrine-type alkaloids. One product that listed Má Huáng as an ingredient contained no detectable ephedrine-type alkaloid. In products containing measurable quantities of these compounds, total alkaloid levels ranged from 0.3 to 56 mg/g.
Spectrophotometric Method for Determination of Paraquat in Food and Biological Samples
Authors: Kesari Ritu , Rai Manish , Gupta Vinay Kumar 
Published: February 2020

Abstract
A sensitive spectrophotometric method was developed for determination of paraquat, a widely used herbicide. Paraquat was reduced with glucose in an alkaline medium, and the blue radical ion obtained was measured at 600 nm. Beer’s law was obeyed at 0.1–1.2 ppm paraquat. The molar absorptivity was 1.26 × 105 L mol-1 cm-1. The standard deviation and relative standard deviation were ± 0.007 and 2.0%, respectively, for 5 μg paraquat/10 mL analyzed over 7 days. The method was free from interference by other commonly used pesticides and metal ions. The method may be used to the determine paraquat in plants, fruits, grains, water, blood, and urine.
Quantitative Analysis of Aloe vera Mucilaginous Polysaccharide in Commercial Aloe vera Products
Authors: Ross Samir A , Elsohly Mahmoud A , Wilkins Scott P 
Published: February 2020

Abstract
A quantitative method using size exclusion chromatographic (SEC) analysis was performed to determine the concentration of Aloe vera mucilaginous polysaccharide (AVMP) in 18 selected commercial preparations. Of the 18 preparations studied, 9 contained quantitatable amounts of AVMP at 0.22 to 1.30 mg/mL, and 2 showed trace amounts (&lt;0.2 mg/mL). Seven preparations showed no detectable levels of AVMP. The method may be adapted to standardize these and similar preparations.
Simultaneous Determination of Alliin and Allicin in Allium Plants and Their Products by Liquid Chromatography
Authors: Mochizuki Emiko , Yamamoto Takao , Horie Masakazu , Ikai Yoshitomo , Nakazawa Hlroyuki 
Published: February 2020

Abstract
Alliin and allicin in garlic and their products are determined simultaneously by ion-pair reversedphase liquid chromatography (LC) with diode array UV detection. Alliin is extracted from fresh garlic, purified by ion-exchange chromatography, and appliedas external standard. Allicin is generated enzymatically from alliin, confirmed by LC, and applied as external standard. Compounds areextracted from samples with water and chromatographed on an octadecylsilane column with gradient elution from 0.01 M phosphate buffer (pH 2.5) with 5 mM heptanesulfonic acid (A) to 0.01 M phosphate buffer (pH 2.5)-acetonitrile (1 + 1; B). Themethod can be used to analyze fresh garlic, spices, garlic preparations, and health foods.
Determination of Phosphorus, Potassium, and Magnesium in Fertilizers by Inductively Coupled Plasma–Atomic Emission Spectroscopy and Comparison with Other Techniques
Authors: Hamalovâ Martina , Hodslavská Jiřina , Janos Pavel , Kanický Viktor 
Published: February 2020

Abstract
Phosphorus, potassium, and magnesium in 12 fertilizers were determined by inductively coupled plasma–atomic emission spectroscopy (ICP–AES), and results were compared with those obtained by standard gravimetry (phosphorus) and atomic absorption spectrometry (AAS) (potassium and magnesium). ICP–AES and gravimetry were also used to determine water- and citrate-soluble phosphorus in fertilizers. In all cases, precision and accuracy of the ICP–AES method were satisfactory. Certain differences, probably not significant for routine analyses, were observed between ICP–AES and gravimetry in determinations of total and citrate-soluble phosphorus when the measurements were performed strictly under conditions of repeatability.