bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of 2-Ethylhexyl 4-(N-Methyl-N-Nitrosamino) Benzoate in Commercial Sunscreens and Cosmetic Products
Authors: Chou Hardy J , Yates Ronald L , Havery Donald C , Wenninger John A 
Published: February 2020

Abstract
An analytical method has been developed for determination of 2-ethylhexyl 4-(N-methyl-N-nitrosamino) benzoate (NMPABAO), a nitrosamine contaminant in sunscreen products containing 2-ethylhexyl 4-(N,N-dimethylamino) benzoate (Padimate O). The method involves extraction of NMPABAO by column chromatography followed by liquid chromatographic separation and analysis with a nitric oxide detector. To confirm the presence of NMPABAO in sunscreen products, the N-nitrosamine was synthesized and its structure was determined by infrared spectrophotometry, nuclear magnetic resonance spectrometry, and mass spectrometry (MS). For method validation, recovery studies were performed on a commercial suntan lotion, cream, and gel. Recoveries of NMPABAO added to representative test samples averaged 83%. The method has an estimated detection limit of 30 ppb. The method was used to analyze 25 commercial cosmetic and sunscreen products containing Padimate O. Eleven products contained NMPABAO at levels ranging from 160 to 21 000 ppb. NMPABAO presence in 4 products was confirmed by MS at levels ≥4000 ppb. The highest levels of NMPABAO were associated with products that contained the nitrite-releasing preservative 2-bromo-2- nitro-1,3-propanediol.
Determination of Combined Residues of Metalaxyl and 2,6-Dimethylaniline Metabolites in Urine byGas Chromatography/Mass Spectrometry
Authors: Headley John V , Maxwell Donald B , Swyngedouw Christopher , Purdy John R 
Published: February 2020

Abstract
A gas chromatographic/mass spectrometric (GC/MS) method for determination of combined residues of the fungicide metalaxyl and its metabolites in urine containing the 2,6-dimethylaniline moiety is described. The method is a modification of a method of Balasubramanian and Perez for analysis of metalaxyl invegetables. Noted modifications include replacement of steam extraction with extraction by methylene chloride and use of electron impact ionization GC/MS in the selected-ion mode. The method is linear over the range of 0.1-5 μg 2,6- dimethylaniline/g urine and has a detection limit of 0.025 μg/g.
Comparison of Cleanup Techniques for Simple Method for Analysis of Selected Organophosphorus Pesticide Residues in Molluscs
Authors: Hernández Félix , Serrano Roque , Beltran Joaquim , López Francisco J 
Published: February 2020

Abstract
A simple method for determination of 5 organo phosphorus pesticides (dimethoate, chlorfenvin phos, chlorpyrifos, methidathion, and phosmet) in molluscs (Mytilus galloprovincialis and Venus gallina) was developed, with special attention to cleanup. Organophosphorus pesticides were extracted with acetonitrile-acetone (90 + 10, v/v) in a high-speed blender. Two cleanup procedures were used to defat extracts prior to injection into a gas chromatograph: liquid-liquid partition with acetoni trile-hexane and adsorption column chromatography with silica gel. The latter was more efficient for elimination of fat and fractionation of pesticides with different polarities. Limits of detection of the overall procedure including extraction and cleanup ranged from 0.2 to 1 ng/g. Quantitative recoveries for pesticide concentrations ranging from 1 to 10 000 ng/g were obtained.
Collection and Analysis of Butyltin Compounds in Air at Nanogram-Per-Cubic-Meter Levels
Authors: Swami Kamal , Narang Rajinder S 
Published: February 2020

Abstract
An analytical method for determining butyltin chlo rides in air at low nanogram-per-cubic-meter levels was developed. Butyltin chlorides investigated were mono-n-butyltin trichloride (MBTC),di-n-butyltin dichloride (DBTC), and tri-n-butyltin chlo ride (TBTC). These tin chlorides were trapped on cartridges packed with Porapak-N, eluted with methylene chloride containing 0.3% HCI, hy dridized with sodium borohydride, and analyzed by capillary gas chromatography with flame photometric detection. On the basis of a 20 m3 sample, a detection limit of 0.05 ng/m3 can be achieved.
Identification of Phylloquinone (Vitamin K1) as an Unknown Peak in Electron Capture Detection Gas Chromatograms of Pyrethroid Insecticide Residues
Authors: Imanaka Masaaki , Kadota Minoru , Kumashiro Kazuo , Mori Tadashige 
Published: February 2020

Abstract
An unknown peak was observed in spinach extract during routine analysis of 7 pyrethroid insecticides by gas chromatography with electron capture detection (GC-ECD) using a DB-1 column (20 m x 0.25 mm id, 0.1 μm film thickness). It eluted later than the 7 pyrethroids, and it was also found in other agricultural crops. The intensity of the unknown peak was related to the green color of the sample: It was absent in white vegetables such as radish root or onion. Data from GC/direct deposi- tion/Fourier-transform infrared spectroscopy (FTIR) suggested it might be phylloquinone (vitamin K1). The identity was confirmed also by using electron impact capillary GC/mass spectrometry (MS). Although phylloquinone has no halogens, it showed very high sensitivity by ECD (63Ni), responding to 10 pg.
Determination of Thiabendazole Residues in Whole Citrus Fruits by Liquid Chromatography with Fluorescence Detection
Authors: Arenas Rene V , Rahman Hafizur , Johnson Nelson A 
Published: February 2020

Abstract
An existing liquid chromatographic (LC) methodfor determination of thiabendazole (TBZ) residues inor on whole green bananas and potatoes was applied to whole, unwashed citrus fruits. The method is applicable for determining TBZ residues in whole oranges,grapefruits, tangerines, and lemons. TBZ is extracted from citrus homogenate with ethyl acetate, and theextract is cleaned up on a cation-exchange, solid-phase extraction column. The purified extract is analyzed by LC with a cation-ex change column and fluorescence detection. Average recovery of TBZ from whole citrus fruits fortified with TBZ at 0.05-20 ppm was 96%. The assay provides a simple, rapid, and sensitive method for monitoring TBZ residues in whole citrus fruit.
Gradient Liquid Chromatographic Method for Determination of Chlorhexidine and Its Degradation Products in Bulk Material
Authors: Doub William H , Ruhl Don D , Hart Brad , Mehelic Paul R , Revelle Larry K 
Published: February 2020

Abstract
A liquid chromatographic method was developed for determination of chlorhexidine and its degradation products in unformulated drug substance. A nonlinear gradient from 80% 0.1 M ammonium acetate buffer, pH 5.0, to 20% buffer over 90 min (balance is acetonitrile) is applied to a 3 μm octadecylsilane bonded-phase column. The drug and some of its degradation products are determined at 230 nm. Of 11 previously identified degradation products, 9 are determined with good precision (relative standard deviation of peak area is &lt;2%).
Liquid Chromatographic Determination of Benzylpenicillin and Cloxacillin in Animal Tissues and Its Application to a Study of the Stability at –20°C of Spiked and Incurred Residues of Benzylpenicillin in Ovine Liver
Authors: Gee Hock-Eng , Ho Koon-Bay , Toothill John 
Published: February 2020

Abstract
A method was developed for determining benzylpenicillin and cloxacillin in animal tissues. Samples are extracted with acetonitrile, and the extract is cleaned up on a C18 solid-phase extraction (SPE) cartridge, derivatized, and quantitated by liquid chromatography with UV detection at 325 nm. The method was validated on spiked bovine kidney, liver, and muscle tissues. Kidney was spiked at 0.01,0.05, and 0.20 mg/kg; liver and muscle were spiked at 0.20 mg/kg. Recoveries were 75–100%, with coefficients of variation of 2–7%. The method was further validated on kidney, liver, and muscle tissues from 2 sheep dosed with Aquacaine G suspension (containing benzylpenicillin). Mean levels of benzylpenicillin in these tissues ranged from 0.02 to 4.06 mg/kg, with coefficients of variation of replicate analyses between 3 and 7%. The limit of detection was approximately 0.005 mg/kg for benzylpenicillin and cloxacillin in kidney, liver, and muscle tissues. This method was used to study the stability of both spiked and incurred residues of benzylpenicillin in ovine liver during storage at –20°C for 3 months. Assuming the rate of loss follows a first-order kinetic decay, the mean half-life of benzylpenicillin in liver is 62 days for spiked tissues and 71 days for tissues with incurred residues.
Analysis of Fermented Milk Products by Near-Infrared Reflectance Spectroscopy
Authors: Rodríguez-Oxero José L , Hermtoa Marià 
Published: February 2020

Abstract
Fat, protein, and total solids in fermented milk were determined by near-infrared reflectance spectroscopy (NIRS). A set of 107 samples from diverse types of fermented milk (whole, skimmed, with added flavors, and without added flavors) were used to calibrate the instrument by modified partial least-square regression. Global calibration, using all samples, was more effective than specific calibrations using fewer samples of each type. Standard errors of a calibration were 0.071 for fat, 0.075 for protein, and 0.083 for total solids. Values of the correlation coefficient square (R2) were 0.997 for fat, 0.981 for protein, and 1.000 for total solids. Calibration was validated with an independent set of 34 samples of the same types. Standard errors of validation were 0.08,0.14, and 0.25 for fat, protein, and total solids, respectively, and values of R2 for the regression of measurements by NIRS versus reference methods were 1.00 for fat and total solids and 0.94 for protein. When Standard 128 of the International Dairy Federation was used to compare NIRS results with those from reference methods, no significant differences were found (p = 0.05).
Liquid Chromatographic Determination of Fentin Acetate in Fentin and Maneb Formulations
Authors: Papadopoulou-Mourkidou Euphemia , Patsias John , Papadopoulos George , Galanis Costas 
Published: February 2020

Abstract
A normal-phase liquid chromatographic (LC) system is presented for determination of fentin acetate in fentin and fentin-maneb wettable powder formulations. Fentin acetate is extracted from both formulations with glacial acetic acid-hexane (20 + 80), and the extract is analyzed after appropriate dilution. An isocratic LC system equipped with a photodiode array detector and a silica gel column, which is eluted with glacial acetic acid-hexane (5 + 95), are used. Quantitation at 258.5 nm is based on an external standard calibration curve. Relative standard deviations were 0.2 and 2.3% for the mean levels (w/w) of fentin acetate determined in fentin and fentin-maneb formulations, respectively.
Determination of Low Concentrations of Acetochlor in Water by Automated Solid-Phase Extraction and Gas Chromatography with Mass-Selective Detection
Authors: Lindley Chris E , Stewart Jeff T , Sandstrom Mark W 
Published: February 2020

Abstract
A sensitive and reliable gas chromatographic/mass spectrometric (GC/MS) method for determining acetochlor in environmental water samples was developed. The method involves automated extraction of the herbicide from a filtered 1 L water sample through a C18 solid-phase extraction column, elution from the column with hexane-isopropyl alcohol (3 + 1), and concentration of the extract with nitrogen gas. The herbicide is quantitated by capillary/column GC/MS with selected-ion monitoring of 3 characteristic ions. The single-operator method detection limit for reagent water samples is 0.0015 μg/L Mean recoveries ranged from about 92 to 115% for 3 water matrixes fortified at 0.05 and 0.5 μg\L. Average single-operator precision, over the course of 1 week, was better than 5%.
Suitability of Several Statistical Models to Simulate Observed Distribution of Sample Test Results in Inspections of Aflatoxin-Contaminated Peanut Lots
Authors: Whitaker Thomas , Giesbrecht Francis , Wu Jeremy 
Published: February 2020

Abstract
The acceptability of 10 theoretical distributions to simulate observed distribution of sample aflatoxin test results was evaluated by using 2 parameter estimation methods and 3 goodness of fit (GOF) tests. All theoretical distributions were compared with 120 observed distributions of aflatoxin test results of farmers' stock peanuts. For a given parameter estimation method and GOF test, the negative binomial distribution had the highest percentage of statistically acceptable fits. The log normal and Poisson-gamma (gamma shape parameter = 0.5) distributions had slightly fewer but an almost equal percentage of acceptable fits. For the 3 most acceptable statistical models, the negative binomial had the greatest percentage of best or closest fits. Both the parameter estimation method and the GOF test had an influence on which theoretical distribution had the largest number of acceptable fits. All theoretical distributions, except the negative binomial distribution, had more acceptable fits when model parameters were determined by the maximum likelihood method. The negative binomial had slightly more acceptable fits when model parameters were estimated by the method of moments. The results also demonstrated the importance of using the same GOF test for comparing the acceptability of several theoretical distributions.
Determination of Phenylbutazone Residues in Bovine Milk by Liquid Chromatography with UV Detection
Authors: De Veau E J  Ian 
Published: February 2020

Abstract
A published liquid chromatographic (LC) method was modified for quantitation of phenylbutazone (PBZ) residues in the range of 25-300 ng/mL in bovine milk. Milk samples (1 m└) were diluted with absolute ethanol and 25% NH4OH. Diethyl ether and petroleum ether were added sequentially to the milk extract and the mixture was agitated on a Vortex mixer to partition out milk fat. The organic phase was removed and discarded. Tetrahydrofuran- hexane (1 + 4) was added to the aqueous phase and the extract was acidified with 3M HCI. The samples were mixed on a Vortex mixer for 30 min, and centrifuged. The organic layer, containing PBZ, was transferred to a clean test tube. The organic solvents were evaporated to dryness under a stream of N2 at room temperature. The resulting extract was dissolved in 1 m└ mobile phase and filtered before injection. The chromatographic system was a C18 reversed-phase column connected to a UV detector set at 264 nm. Recoveries of PBZ from raw bovine milk fortified at 25- 300 ng/mL ranged from 79 to 84%; relative standard deviations (RSDs) ranged from 6 to 7%. The RSDs for incurred PBZ quantitated from 34 to 229 ng/mL ranged from 1 to 4%.
Determination of Decarbamoyl Saxitoxin and Its Analogues in Shellfish by Prechromatographic Oxidation and Liquid Chromatography with Fluorescence Detection
Authors: Lawrence James F , Wong Barbara , Ménard Cathie 
Published: February 2020

Abstract
Oxidation and chromatographic conditions for detecting the decarbamoyl analogues of several paralytic shellfish poison (PSP) toxins were studied. Prechromatographic oxidation with periodate or hydrogen peroxide under slightly alkaline conditions was used as previously reported for the parent PSP toxins. Both periodate and hydrogen peroxide oxidations produced 2 fluorescent products separable by liquid chromatography for each decarbamoyl (dc) toxin (dc-saxitoxin, dc-neosaxatoxin and dcgonyautoxins 2 and 3). Decarbamoyl saxitoxin produced the same 2 products as did dc-neosaxitoxin but in different ratios. One of these products was the same as the one obtained with neosaxitoxin after periodate oxidation. Decarbamoyl gonyautoxins 2 and 3 (together) produced 2 products, one of which was the same as the major product obtained with gonyautoxins 1 and 4 (together) after periodate oxidation. Decarbamoyl gonyautoxins 1 and 4 were not available for study. The method was used to detect dc-saxitoxin and dc-gonyautoxins 2 and 3 in shellfish extracts
TCDD Residues in Fish and Shellfish from U.S. Waterways
Authors: Firestone David , Fehrtnger Norbert V , Walters Stephen M , Kozara Ronald J , Ayres Russell J , Ogger John D , Schneider Louis F , Glidden R Michael , Ahlrep James R , Brown Patrick J , Ford Susanna E , Davy Raphael A , Gulick Daniel J , Mccullough Bruce H , Sittig Robert A , Smith Paul V , Syvertson Carl N , Barber Mildred R 
Published: February 2020

Abstract
TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) in the edible portion of fish and shellfish from various U.S. waterways has been monitored since 1979. Analytical results for the period 1979-1994 are reported. Extracts obtained after column chromatographic and liquid chromatographic cleanup were examined by electron capture detection-gas chromatography (GC), and final quantitation and confirmation were performed by GC/mass spectrometry with multiple ion detection. Analyses of 1623 test samples indicated that TCDD residues in fish and shellfish were not widespread but rather were localized in areas near waste sites, chlorophenol manufacturers, and pulp and paper mills. Analytical results indicated that levels in aquatic species from these sites have been declining steadily. No TCDD (limit of detection and confirmation, 1 - 2 ppt) has been found in recent years in aquatic species from most Atlantic, Pacific, and Gulf of Mexico sites and Great Lakes other than Lake Ontario and Saginaw Bay (Lake Huron).
A Simplified Method for Determining Undeclared Sweeteners Added to Pure Orange Juice
Authors: Iuliano Theresa A 
Published: February 2020

Abstract
Previous research has described methods for monitoring unique oligosaccharides as indicators of adulteration of pure orange juice with undeclared sweeteners. Modifications are reported here that streamline the method for routine analysis of large numbers of samples. Sample preparation is faster and more efficient, allowing preparation of up to 24 samples at one time. Oligosaccharides are eluted isocratically at 30�C, decreasing retention times and eliminating the need for column reequilibration between injections. Oligosaccharide profiles of commercially available sweeteners and fortified orange juice samples analyzed under the modified conditions demonstrate that the method reduces analysis time by &gt;50%, while at the same time improving resolution and maintaining established detection limits.
Escherichia coli 0157:H7 Visual Immunoprecipitate Assay: A Comparative Validation Study
Authors: Feldsine Philip T , Forgey Robin L , Falbo-Nelson Maria T , Brunelle Sharon L 
Published: February 2020

Abstract
A wide variety of food products, with emphasis on raw meat products, were analyzed simultaneously by 3 methods: the Assurance Escherichia coli 0157:H7 (EHEC) enzyme immunosorbent assay (EIA), the EHEC visual immunoprecipitate assay (VIP), and a modified Bacteriological Analytical Manual (BAM) culture method. This paper reports results of a comparative study of the Assurance and modified BAM methods. In this comparative study, 1050 samples and controls gave false-negative rates of 1.0 and 0%, respectively, for the Assurance EIA and the modified BAM culture methods. The overall agreement between the 2 methods was 99.4%. Cultural confirmation of presumptive positive samples was problematic because competitive flora were present in higher levels than EHEC in the enrichment broth after incubation and the target organism had nondescript characteristics on the primary selective agar, hemorrhagic coli agar, which necessitated picking of additional colonies in many instances.
Effect of Seeds on Bile-Enzymatic-Gravimetric Analysis of Total Dietary Fiber
Authors: Cranker Kenneth J , Phillips Katherine M , Gonzales Maria Carmen Rita V , Stewart Kent K 
Published: February 2020

Abstract
Dietary fiber sometimes is defined chemically as nonstarch polysaccharides plus lignin or as other specific chemical entities. Analysis of dietary fiber according to a chemical definition typically involves gas chromatography, which allows separation and quantitation of chemical constituents that are added to arrive at a dietary fiber value. Other definitions of fiber are broader, defining it to be whatever is not digested in the alimentary tract. Analytically, this definition translates into the gravimetric sum of the material remaining after a series of enzymatic and chemical treatments that simulate in vivo digestion. Various methods reflect the gravimetric definition, which might include as dietary fiber some protein, resistant starch, and even lipids that are not digested by particular assay conditions. We used a recently proposed bile-enzymatic-gravimetric assay for total dietary fiber on commonly consumed seeds (hulled and unhulled sesame, caraway, and poppy) and visually found these seeds to be undigested. We then determined the impact of the undigested seeds on measured dietary fiber content by spiking homogenized daily menus with 5% by weight of these seeds and calculating recoveries with 2 assumptions: seeds are 100% fiber because they are not digested, and the fiber content of seeds is as determined by assay. Calculated recoveries were very different depending on which assumption was made (71-90% or 99109%, respectively), and the difference was closely related to the seed’s protein content.
Determination of Calcium in Certain Fertilizers by Inductively Coupled Plasma Atomic Emission Spectrometry: Studies of Some Spectral and Interelement Effects at Different Wavelengths
Authors: Matilainen Rose , Tummavuori Jouni 
Published: February 2020

Abstract
Four analytical wavelengths (393.366, 396.847, 317.933, and 422.673 nm) were used to determine Ca in 2 fertilizers by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Matrix effects were studied by adding to real fertilizer solutions fertilizer elements that are known or believed to interfere with Ca determination. Matrix effects were calculated by multiple linear regression. Interference was caused by S, K, or B. At 422.673 nm, the interference of B and K is a spectral effect, and at 396.847 and 317.933 nm, the interference of S and K is an interelement effect. At 393.366 nm, no linear interference was found. The best wavelength for determining Ca in fertilizers by ICP-AES is 396.847 nm.
Measurement of Total Starch in Cereal Products by Amyloglucosidase-α-Amylase Method: Collaborative Study
Authors: Mccleary Barry V , Gibson Trevor S , Mugford David C ,   Collaborators:, Lukow O , Jackson D S , Rabe E , Patel N , Williams P C , Gelroth J , Camire M E , Chibbar R N , Ingelin M , Niemann C , Grant L A , Peterson D M , Corke H , Sanders P , Muir J , Choct M , Schmidt J , Walker R , Blakeney A B , Logue S , Tarr A , Gibson T , Batey I , Dynes J , Miklaszewicz T , Panozzo J , McCleary B , Li B W , Hofer P , Arndt E , Thomas M , Depalo R 
Published: February 2020

Abstract
American Association of Cereal Chem- ists/AOAC collaborative study was conducted to evaluate the accuracy and reliability of an enzyme assay kit procedure for measurement of total starch in a range of cereal grains and products. The flour sample is incubated at 95°C with thermostable α-amylase to catalyze the hydrolysis of starch to maltodextrins, the pH of the slurry is adjusted, and the slurry is treated with a highly purified amyloglucosidase to quantitatively hydrolyze the dextrins to glucose. Glucose is measured with glucose oxidase-peroxidase reagent. Thirty-two collaborators were sent 16 homogeneous test samples as 8 blind duplicates. These samples included chicken feed pellets, white bread, green peas, high- amylose maize starch, white wheat flour, wheat starch, oat bran, and spaghetti. All samples were analyzed by the standard procedure as detailed above; 4 samples (high-amylose maize starch and wheat starch) were also analyzed by a method that requires the samples to be cooked first in dimethyl sulfoxide (DMSO). Relative standard deviations for repeatability (RSDr) ranged from 2.1 to 3.9%, and relative standard deviations for reproducibility (RSDr) ranged from 2.9 to 5.7%. The RSDr value for high amylose maize starch analyzed by the standard (non-DMSO) procedure was 5.7%; the value