bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid Chromatographic Determination of Nitrofuran Residues in Bovine Muscle Tissues
Authors: Angelini Nora M , Rampin Oscar D , Mugica Héctor 
Published: February 2020

Abstract
A liquid chromatographic (LC) method was developed and statistically validated for simultaneous determination of nitrofurazone, nitrofurantoin, furazolidone, and furaltadone residues in bovine muscle tissues. These antimicrobial residues in samples stabilized at pH 6.0 were extracted with acetonitrile and purified by liquid-liquid partition between dichloromethane-ethyl acetate and hexane saturated with acetonitrile. The acetonitrileethyl acetate extract was concentrated, and drug residues were dissolved in LC mobile phase, filtered, and determined by LC. A Cis reversed-phase (ODS Hypersil) column at 35°C, a mobile phase of 0.01 M sodium acetate buffer (pH 4.5)-acetonitrile (70 + 30), and a UV/visible diode array detector at 365 nm were used. The retention times and UV spectra of peaks in spiked samples were compared with those of known nitrofurans. Limits of detection (LD) and quantitation (LQ) were 1 and 2 μg/kg, respectively. Average recoveries were 76% (range, 60-110%). Relative standard deviations ranged from 6 to 18% at 5 fortification levels from 1.5 to 20 μg/kg. (Fortification levels for furaltadone were 3 to 40 μg/kg). The method was used to analyze 350 samples per year from 1993 to 1995.
Determination and Degradation of Methomyl in Tomatoes and Green Beans Grown in Greenhouses
Authors: Garcia M D Gil , Vidal Martínez , Galera M Martínez , Torreblanca C Rodríguez , Gonzalez C 
Published: February 2020

Abstract
A liquid chromatographic (LC) method using UV detection at 233 nm was used to study the degradation of methomyl in tomatoes and green beans grown in greenhouses. A liquid-liquid extraction with CH2CI2-methanol (90 + 10, v/v) and a cleanup step with Florisil were combined with LC to isolate, recover, and quantitate the pesticide. Average recoveries obtained at spike levels of 0.03 and 0.40 mg/kg were 83.2-84.7% for tomatoes and 83.387.5% for green beans. Determination limits were 0.03 mg/kg for tomatoes and 0.01 mg/kg for green beans. Levels of methomyl residues were studied in tomatoes and green beans grown in an experimental greenhouse to establish the effect of the kind of greenhouse, application dose, species grown, and climatic conditions on the degradation of this pesticide. Analysis of variance showed that doses did not affect the response. The half-life, however, is greater in a flat-roof greenhouse than in an asymmetric-roof greenhouse and is significantly longer for green beans than for tomatoes and longer in winter than in spring. A preharvest time of about 5 days may be suitable for green beans sprayed with methomyl. Tomatoes show residue levels at the time of application lower than Spanish minimum residue levels.
Planar Chromatography for the Multiclass, Multiresidue Screening of Chloramphenicol, Nitrofuran, and Sulfonamide Residues in Pork and Beef
Authors: Abjean Jean-Pierre 
Published: February 2020

Abstract
A method is described for multiclass and multiresidue qualitative detection of chloramphenicol, nitrofuran, and sulfonamide residues in animal muscle. The drugs are extracted from 1 g tissue with 2 mL ethyl acetate and purified by silica solidphase extraction. After elution of the cartridge, the collected solution is evaporated, and the residue is dissolved in methanol and chromatographed on a Si60 high-performance thin-layer chromatography plate. After evaporation of solvent, nitrofurans are visualized first by their specific UV photochemical reaction with pyridine. Then chloramphenicol is reduced to its amino derivative, and this derivative and the sulfonamides are visualized by long-wave UV after reaction with fluorescamine. Chloramphenicol, nitrofurans, and sulfonamides are detected at residue level of 10, 5, and 100 μg/kg, respectively, or less in pork and beef.
Liquid Chromatographic Determination of Inositol Hexanicotinate in Formulated Preparations
Authors: Nagarajan Mythili , Waszkuc Ted W , Sun Jidong 
Published: February 2020

Abstract
A precise and selective liquid chromatographic procedure for determining inositol hexanicotinate (IHN) in formulated preparations was developed and validated. IHN was dissolved in dimethyl sulfoxide, diluted with acetonitrile, chromatographed on a Nova-Pak C18 column with a mobile phase of water-methanol (40 + 60, v/v), and detected at 262 nm. The correlation coefficient of the calibration curve was 0.9995 over the range 0.050.15 mg/mL. Overall recovery of IHN was &gt;97%. Coefficients of variation for intra- and interday precisions were &lt;2%.
Determination of Glucose in Nonalcoholic Beverages by a Biosensor Coupled with Microdialysis Fiber Samplers
Authors: Centonze Diego , Zambonin Carlo G , Palmisano Francesco 
Published: February 2020

Abstract
Glucose in soft drinks, fruit juices, and milk was determined by an interference-free amperometric biosensor coupled with microdialysis fiber samplers. The biosensor was based on glucose oxidase (GOx) immobilized on a platinum electrode by an electroproduced bilayer of overoxidized polypyrrole (Pt/PPyox,GOx/PPyox). The first undercoating of PPyox entrapped GOx, and the second, grown onto the first, limited glucose diffusion, hence improving linearity of response. Such a biosensor coupled with microdialysis sampling extended the linear range to 500 mM. The biosensor response was not affected by sample pH variations in the range 2–10. The influence of flow rate on biosensor response was also investigated. The glucose response of the device in both continuous and discontinuous flow injection experiments showed good repeatability and sensitivity. Real samples containing high glucose concentrations were easily analyzed without pretreatment such as dilution or filtration. Results were in good agreement with those of the reference method.
Determination of Biogenic Amines in Cheese
Authors: Vale Silvana R , Glória M Beatriz A 
Published: February 2020

Abstract
A liquid chromatographic (LC) procedure for determining 10 biogenic amines in cheese is described. The method is based on ion-pair chromatography on a reversed-phase column with postcolumn derivatization with o-phthaldialdehyde and fluorometric detection. It allowed simultaneous determination of 10 amines in &lt;80 min: histamine, tyramine, tryptamine, 2-phenylethylamine, serotonin, agmatine,spermine, spermidine, putrescine, and cadaverine. Linearity for each amine was observed between 0.5 and 6.0 μg/mL. Detection limits ranged from 0.004 to 0.009 μg/20 μL, and determination limits ranged from 0.066 to 0.149 mg/100 g. Amino acids and other amines did not interfere with determination of biogenic amines. Three extractantsmethanol, hydrochloric acid, and trichloroacetic acidwere compared in their efficiency to recover aminesfrom spiked samples. Purification of the cheese extract was required prior to LC to avoid interference from compounds in the cheese matrix. Hydrochloric acid extraction followed by purification with diethyl ether gave best recoveries for all the amines (75.5-112.3%). The method is simple, fast, and reliable. It can be used to study the technological and toxicological implications of biogenic amines in cheeses.
Comparison of Methods and Kits for Colorimetric Determination of Residual Chlorine in Water
Authors: Serrat F Bosch , Morell G Bosch , Polo D Rodriguez 
Published: February 2020

Abstract
The use of 3,3',5,5'-tetramethylbenzidine (TMB) for residual chlorine determination in water offers 2 possibilities, one at pH 1-2 and absorbance measurement at 450 nm and another at pH 3.8-5.8 and measurement at 650 nm. The reaction of chlorine with TMB reaches its maximum sensitivity at pH 1-2. The detection limit is 2 ng/mL. A calibrated scale for colorimetric determination of residual chlorine in water with 3,3',5,5'-tetramethylbenzidine (TMB), prepared with tropaeolin O (C.I. 14270), is described. This scale is stable for several months and can be useful in replacing the conventional and much less stable scale prepared from standard solutions of oxochlorate (I). Kits for determination of residual chlorine in water by visual comparison, including a 3-dimensional scale or a color scale printed on paper or a plastic material, are described in this article. A comparative study of the analytical qualities and applications of the TMB methods against other reagents methods is performed.
Comparison of Environmental Chemical Results for Split Samples Analyzed in Different Laboratories
Authors: Grant Clarence L , Jenkins Thomas F , Mudambi Anand R 
Published: February 2020

Abstract
Data comparisons were made for split or co-located samples analyzed in contract laboratories and quality assurance (QA) laboratories during environmental studies directed by the U.S. Army Corps of Engineers. Archived results were analyzed statistically as concentration ratios (contract laboratory/QA laboratory). Concentration ratios were found to be lognormally distributed, and this was the model used for comparisons. For metals in soils and volatile organic compounds (VOCs) in groundwater, 10.2% of metal ratios in soils and 5.6% of VOC ratios in groundwater exceeded limits of 0.40-2.50. Considering that both methods are multianalyte, we find that only 4.0% of the metal samples and 2.0% of the VOC samples had more than one outlier ratio per sample. More recent data produced very similar results. For VOCs, total petroleum hydrocarbons (TPHs), and explosives in soils, limits of 0.25-4.00 are suggested with the understanding that large improvements are badly needed. Even with these wide limits, approximately 42% of VOCs, 14% of TPHs, and 11% of explosives contract laboratory/QA laboratory ratios were outside these limits. Here, too, the most recent data yielded very comparable results. Sampling and preparation procedures for VOCs in soils requires immediate attention, but all methods can and should be capable of producing improved agreement between laboratories.
Quantitation of Penicillin G in Medicated Premix Feeds by Micellar Electrokinetic Capillary Chromatography
Authors: Cutting Jeffrey H , Hurlbut Jeffrey A , Sofos John N 
Published: February 2020

Abstract
A micellar electrokinetic capillary chromatographic (MECC) method for quantitation of penicillin G in medicated premix feeds was compared with the A0AC microbiological cylinder plate method. Feed was extracted according to the AOAC method, enabling comparison of both methods with the same extract. The MECC method detected penicillin G within 20 min, using a 150 mM sodium dodecyl sulfate (SDS)-20 mM sodium borate run buffer and a UV photodiode array detector at 210 nm. Recoveries from 5 replicates of medicated feed containing 117 g penicillin G/kg and then spiked to give a concentration of 176 g/kg were 98.4-108%, with a relative standard deviation (RSD) of 3.76% for the MECC method, and 102-104% with RSD of 1.06% for the AOAC microbiological cylinder plate method. Using a 5-point calibration curve, the MECC method detected and quantitated penicillin G in medicated premix feeds within 3 h, versus 24 h for the AOAC microbiological cylinder plate method.
Assay of Chlortetracycline in Animal Feeds by Liquid Chromatography with Fluorescence Detection
Authors: Houglum Joel E , Larson Richard D , Knutson Ann 
Published: February 2020

Abstract
A liquid chromatographic (LC) method is described to assay chlortetracycline (CTC) at gram-per-ton and gram-per-pound levels. Feeds and premixes are extracted with acid-acetone following AOAC Method 957.23B(h). Extracts are filtered and quantitated by LC using a Ciβ column and fluorescence detection at 390 nm excitation and 512 nm emission. The mobile phase (1.5 mumin) uses a methanol gradient with an initial hold time of 5 min at 35% methanol followed by an increase to 60% methanol over 8 min. The aqueous component contains CaCI2, disodium EDTA, and sodium acetate buffered to pH 6.5. The method provides significant improvement in selectivity and limit of quantitation compared to LC with UV detection. Recovery of spiked samples averaged 98.1% and assay of samples correlated closely with the results obtained with AOAC microbiological Method 967.39. CTC and epi-CTC eluted at approximately 12.5 and 4.0 min, respectively. No interference was observed from several drugs and other antibiotics often used in combination with CTC in feeds.
Determination of Pirlimycin Residue in Milk by Liquid Chromatographic Analysis of the 9-Fluorenylmethyl Chloroformate Derivative
Authors: Heller David N 
Published: February 2020

Abstract
A procedure to determine pirlimycin residues in bovine milk was developed. Pirlimycin was extracted from milk after protein precipitation and 2 stages of liquid–liquid partitioning. The extract was evaporated to dryness, redissolved in dilute base, and derivatized with 9-fluorenylmethyl chloroformate (Fmoc) to impart a chromophore for ultraviolet (UV) detection. The derivatized extract was analyzed by reversed-phase liquid chromatography (LC). Pirlimycin concentration was calculated from the peak height of the extract by using a linear regression standard curve prepared from a series of derivatized standards. The procedure's performance in the range of the regulatory tolerance (0.4 ppm) was validated by replicate analysis of control, fortified control, and residue-incurred bovine milk. Average recoveries at 0.2, 0.4, and 0.8 ppm were 91, 88, and 87%, respectively, and coefficients of variation were 5,4, and 1%, respectively. Overall recovery for all samples was 89%, with 4% coefficient of variation. Linear regression analysis of LC/UV results versus results from a previously published LC/mass spectrometric assay gave a slope of 0.95, with a correlation coefficient of 0.98.
Analysis of Aflatoxins in Poultry and Pig Feeds and Feedstuffs Used in Colombia
Authors: Céspedes Angel E , Diaz Gonzalo J 
Published: February 2020

Abstract
Feedstuffs and mixed feeds used for poultry and pig nutrition in Colombia were analyzed for aflatoxins by using a liquid chromatographic technique with a limit of detection of 1 μg/kg for each aflatoxin (B1, B2, G1 and G2). Samples of grain sorghum, maize, processed soybean, rice meal, cottonseed meal, and poultry and pig feeds, representative of Colombian production for the 1995–1996 harvest, were taken from feed-manufacturing plants in various cities. Aflatoxins were detected in 11 of 45 samples of sorghum, 4 of 33 samples of maize, 8 of 22 samples of rice meal, 15 of 17 samples of cottonseed meal, 1 of 12 samples of other feedstuffs, 12 of 30 samples of poultry feed, and 7 of 16 samples of pig feed. Aflatoxins were not detected in soybean. Only 9 of 58 positive samples contained total aflatoxin levels exceeding maximum tolerable limits in Colombia.
Determination of Tolclofos-Methyl in Soil and Lettuce by Gas Chromatography
Authors: Gennari Mara , Cignetti Alessandro , Négre Michéle 
Published: February 2020

Abstract
Two simple methods for the determination of tolclofos-methyl in soil and lettuce are presented. Soil samples were extracted with a methanol–water solution (9 + 1, v/v). The extract was cleaned up on a LC C18 SPE cartridge. The method was tested on 4 soils having very different physico-chemical characteristics and gave recoveries &gt; 70% and a determination limit of 0.02 mg/kg soil. Lettuce samples were extracted with n-hexane. The extract was cleaned up on florisil SPE cartridges. The recoveries were &gt; 83% and the determination limit was 0.01 mg/kg lettuce.
Fully Automated Determination of Pesticides in Wine
Authors: Kaufmann Anton 
Published: February 2020

Abstract
A fully automated solid-phase extraction gas chromatographic/mass spectrometric (SPE/GC/MS) method was developed for determination of pesticides in wine. All steps from aspiration of infiltrated wine to printout of the integrated chromatogram were performed without human interaction. A dedicated robot performed addition of internal standard, application of wine onto the SPE cartridge, elution of analytes, drying and concentrating of eiuate, and passing of concentrate to the GC sampler. All steps were performed in standard liquid chromatography/GC vials, using a minimum of organic solvent. The method permits determination of 21 different pesticides. Individual detection limits were 0.005–0.01 mg/L. The regression coefficients relating to linearity were &gt; 0.99; only 4,4-dichloro-benzphenone and dicofol showed lower coefficients. The recoveries for 17 pesticides ranged from 80 to 115%.
Evaluation of Materials as Bacterial Spore Carriers for Testing Disinfectants
Authors: Gangi Victor J , Leonard Ira E , Rodriguez Allison A , Margolin Aaron B 
Published: February 2020

Abstract
Prototype objects made of steel, glass, and various polymers were evaluated in relation to currently used objects made of silk suture and porcelain for their use as bacterial spore carriers for testing the sporicidal activity of disinfectants. The carriers were inoculated with spores of Bacillus subtilis. Spore retention was determined by detachment from the carriers by sonication and rinsing. Inoculated carriers were exposed to 2.5N HCI and 2.5% glutaraldehyde solutions to determine the effect of carrier material on spore inactivation. Carriers with the highest and lowest spore retention were steel-silicone mix carriers (1.7 × 106 spores/carrier) and polyvinylchloride cylinders (3.8 × 105 spores/carrier), respectively. Spore adhesion to carrier objects was not directly proportional to carrier surface area. Spores on silk sutures, grooved steel, and Teflon carriers survived longest in HCI solution. Spores on Teflon, grooved stainless steel, and glass cylinders survived longest in glutaraldehyde solution. In chemical and spore adhesion tests, no significant statistical differences were found between novel carrier materials and current spore carrier materials. The methods used for evaluating carrier materials were reliable and repeatable.
Spectrophotometric Determination of Pyridoxine Hydrochlorine in Pharmaceutical Preparations and Foods
Authors: Srtvidya Kailasam , Balasubramanian Natesan 
Published: February 2020

Abstract
An easy and sensitive spectrophotometric assay of pyridoxine is described. The procedure is based on formation of an azo dye by the reaction of pyridoxine with diazotized 2,4-dinitroaniline followed by the reaction of the dye with Hg2+ ions to form a stable complex with maximum absorbance at 545 nm. The system obeys Beer’s law for 4–75 μg pyridoxine hydrochloride in an overall aqueous volume of 25 mL (correlation coefficient, 0.9998). On extraction into 5 mL butan-1-ol, the system obeys Beer’s law in the range 0.8–15 μg pyridoxine hydrochloride at 545 nm. The color is stable for 60 min in both aqueous and organic phases (molar absorptivity, 3.7 × 104 L/mol · cm; coefficient of variation, 3.1%, n = 10). The pyridoxine contents of pharmaceutical preparations, a processed foodstuff, and 2 rice samples were determined by using the proposed method. Assay reliability was established by recovery studies and parallel determination using a reported method.
A Comparison of Statistical and Empirical Detection Limits
Authors: Su George C C 
Published: February 2020

Abstract
Quantitatable detection limits for 43 diverse analytes analyzed by a variety of analytical methods determined by 2 statistical methods and one empirical method were compared. One statistically derived quantitatable detection limit is the U.S. Environmental Protection Agency's minimum level (ML), which is 10 times the standard deviation of replicates of a single concentration or 3.18 times the method detection limit (MDL). The other statistical method is the alternate minimum level (AML), which is based on statistical calculations of replicates of multiple concentrations but places more weight on the lower concentrations. The empirical method is based on the analysts' experience with actual samples. All 3 approaches agree to within a factor of 5 nearly 70% of the time. This agreement suggests an uncertainty factor of 5 for laboratory analysis at the lowest concentrations at which instruments can perform quantitative analysis. The results also show that both statistical methods probably adequately account for normal matrix effects.
Examining the Origin of Melatonin from a "Natural" Source by Isotope Ratio Mass Spectrometry with Liquid Chromatographic Introduction
Authors: Chen Pei , Osborn Blaire L , Abramson Ferd p 
Published: February 2020

Abstract
The isotopic abundance of 13C often can be used to differentiate between natural and synthetic sources of a given material. These differences are small, and a multicollector isotope ratio mass spectrometer (IRMS) is required. In our laboratory, we developed a liquid chromatographic (LC) introduction system that enables continuous monitoring of 13C isotope ratios for nonvolatile materials without derivatization. The particular question being asked here relates to the source of melatonin in products sold in health food stores. Melatonin is a pineal hormone and its natural source is the brain's pineal gland. The increasing frequency of "mad cow disease" points to a potential danger if bovine pineals were really the source of melatonin in health food preparations. Using a system in which an LC system is interfaced to an IRMS, we evaluated the origin of one melatonin product labeled as being of bovine pineal origin by comparing its 13C/12C ratio to those of pure, synthetic melatonin and 2 other melatonin products labeled as being of synthetic origin. We did not find significant differences among the isotope ratios of these 4 melatonin sources. The finding suggests that bovine pineal melatonin is not present in the product labeled as "natural." The work demonstrates the ability of an apparatus combining LC and IRMS to provide detailed information regarding economic adulteration or fraud.
Estimating Aflatoxin in Farmers' Stock Peanut Lots by Measuring Aflatoxin in Various Peanut-Grade Components
Authors: Whitaker Thomas B , Hagler Winston M , Giesbrecht Francis G , Dorner Joe w , Dowell Floyd E , Cole Richard J 
Published: February 2020

Abstract
Five, 2 kg test samples were taken from each of 120 farmers' stock peanut lots contaminated with aflatoxin. Kernels from each 2 kg sample were divided into the following grade components: sound mature kernels plus sound splits (SMKSS), other kernels (OK), loose shelled kernels (LSK), and damaged kernels (DAM). Kernel mass, aflatoxin mass, and aflatoxin concentration were measured for each of the 2400 component samples. For 120 lots tested, average aflatoxin concentrations in SMKSS, OK, LSK, and DAM components were 235, 2543, 11 775, and 69 775 ng/g, respectively. Aflatoxins in SMKSS, OK, LSK, and DAM components represented 6.9, 7.9, 33.3, and 51.9% of the total aflatoxin mass, respectively. Cumulatively, 3 aflatoxin risk components—OK, LSK, and DAM—accounted for 93.1% of total aflatoxin, but only 18.4% percent of test sample mass. Correlation analysis suggests that the most accurate predictor of aflatoxin concentration in the lot is the cumulative aflatoxin mass in the high 3 risk corn ponents OK + LSK + DAM (correlation coefficient, r = 0.996). If the aflatoxin in the combined OK + LSK + DAM components is expressed in concentration units, r decreases to 0.939. Linear regression equations relating aflatoxin in OK + LSK + DAM to aflatoxin concentration in the lot were developed. The cumulative aflatoxin in the OK + LSK + DAM components was not an accurate predictor (r = 0.539) of aflatoxin in the SMKSS component. Statistical analyses of 3 other data sets published previously yielded similar results.