bluuebunny/crossref_metadata_2025_split huggingface dataset:
Validation of Thin-Layer Chromatography Quantitation Determination with CCD Camera and Slit-Scanning Densitometer
Authors: Petrovic Mira , Kastelan-Macan Marija , Lazaric Katica , Babic Sandra 
Published: February 2020

Abstract
Video densitometric and classical slit-scanning determinations of pesticides on thin-layer chromatographic plates were validated for linearity, precision, and detection limit. A comparison of results showed that slit-scanning densitometry is more sensitive and more precise than video densitometry. However, according to validation requirements, relative standard deviation for video densitometry is acceptable (3.5–5.3%). Linearities are very good and almost identical for both techniques. The main advantage of video technology is speed (a few seconds, compared with 20 min with scanning densitometry). Video technology also provides excellent archiving facility. Image and chromatographic data can be stored together, edited, and used for many tasks.
Reversed-Phase Thin-Layer Chromatography with Different Stationary Phases in Studies of Quantitative Structure–Biological Activity Relationship of New Antimycotic Compounds
Authors: Rózylo Jan K , Zabiñska Anna , Matysiak Joanna , Niewiadomy Andrzej 
Published: February 2020

Abstract
Reversed-phase thin-layer chromatography with RP-8, RP-18, and RP-18W stationary phases was used in quantitative structure–activity relationship (QSAR) studies of new antimycotic compounds. The retention behavior of 10 dihydroxythioben-zanilides was examined for acquisition of log k data. With water–acetone mixtures as the mobile phases, the concentration range for which the correlation between log k′ and acetone concentration is linear was established for each stationary phase and used to determine hydrophobicity parameters log k′w by linear extrapolation. The effect of substituents on retention constants was quantitated by using the group contribution parameters τw. On the basis of QSAR equations obtained from these studies, log k′w, data can be used to predict antifungal activities of dihydroxythiobenzanilides with satisfactory accuracy.
Application of Overpressured Layer Chromatography Combined with Digital Autoradiography and Mass Spectrometry in the Study of Deramciclane Metabolism
Authors: Ludányi Krisztina , Vékey Károly , Szúnyog József , Mincsovics Emil , Karancsi Tamás , Újszászy Kálmán , Nemes Katalin Balogh , Klebovich Imre 
Published: February 2020

Abstract
Overpressured layer chromatography was combined with the highly sensitive and rapid digital autoradiography (DAR) and mass spectrometry to separate, detect, and identify 3H-and 14C-labeled deramciclane metabolites in different biological matrixes. Several minor and major metabolites were separated from plasma and urine samples. The radioactive metabolites localized by DAR were scraped from the thin-layer chromatographic plate and transferred to a mass spectrometer for structure identification. Several metabolites were isolated and characterized, including hydroxy-/V-des- methyl deramciclane, which is described in detail. The combination of techniques is efficient and has good sensitivity: about 2 μg metabolite from a biological matrix was isolated and identified this way.
Determination of Glycarbylamide in Chicken Tissue by High-Performance Liquid Chromatography
Authors: Yamamoto Yuzo , Kondo Fusao 
Published: February 2020

Abstract
A high-performance liquid chromatographic (HPLC) method for determining glycarbylamide (GB) in chicken tissue was developed. GB was extracted with acetonitrile, followed by solid-phase extraction cleanup using a Bond Elut cartridge column with neutral alumina. After the extract had been evaporated to dryness, the residue was dissolved in 1.0 mL 0.1 N sodium hydroxide. Then 1.0 mL 0.1 M potassium dihydrogen phosphate solution was added to it. HPLC separation was done on a 250 × 4.6 mm id TSK-GEL ODS 80™TM column with 0.05M potassium dihydrogen phosphate as the mobile phase. Ultraviolet detection was done at a wavelength of 260 nm. The calibration curve of standard GB solutions was linear between 0.16 and 3 μg/mL (correlation coefficient, r = 0.999). The recovery of GB from chicken muscle spiked at 0.8 μg/g was 88.6 ± 2.3% (mean ± standard deviation, n = 5), and the lower limit of determination was 0.05 μg/g in chicken muscle.
Reference Values of Urinary 3,5,6-Trichloro-2-Pyridinol in the Italian Population—Validation of Analytical Method and Preliminary Results (Multicentric Study)
Authors: Aprea Cristina , Betta Alberto , Catenacci Giovanni , Lotti Andrea , Magnaghi Silvana , Barisano Angelo , Passini Valter , Pavan Ivo , Sciarra Gianfranco , Vitalone Vincenzo , Minoia Claudio 
Published: February 2020

Abstract
The interlaboratory validation of analytical procedures for the assay of urinary 3,5,6-trichloro-2-pyridinol (TCP) in the general Italian population is reported. The determinations were performed by high-resolution gas chromatography (HRGS) with electron capture detection and HRGS with mass spectrometry (MS) in 2 laboratories. The urine samples were from 42 participants from 3 regions of Italy. The results were evaluated by interlaboratory quality control. Urinary TCP concentrations were above the detection limit (1.2 (μg/L) in 88% of the population, with a mean detectable concentration [GM (GSD)] of 2.8 (1.9) (μg/g creatinine (creat). (GM, geometric mean; GSD, geometric standard deviation.) The Mann-Whitney U test showed that wine consumption was a statistically significant variable (p &lt; 0.05) for urinary concentrations of TCP. Analysis of variance of the logarithm of urinary TCP versus wine consumption and diet showed a statistically significant fit. The model used explained 30% of the total variance: wine consumption and diet accounted for 37 and 17% respectively of the explained variance.
Multiresidue Screening of Pesticides in Foods Using Retention Time Locking, GC-AED, Database Search, and GC/MS Identification
Authors: Cook Joanne , Engel Marc , Wylie Philip , Quimby Bruce 
Published: February 2020

Abstract
Fruit and vegetable extracts were screened for over 400 pesticides by gas chromatography with atomic emission detection (GC-AED) and an experimental database. A technique called retention time locking was used to match GC-AED and GC with mass spectrometry (MS) retention times to those of the database. Samples were analyzed for sulfur, nitrogen, phosphorus, and chlorine by GC-AED. Possible pesticides were suggested by database search and identified by GC/MS. Forty-four pesticide standards were analyzed to determine the precision of retention time matching and the accuracy of the database search. Analytical retention times matched database retention times within 0.32 min. Using elemental criteria, the database search identified the correct compound for 41 of 44 pesticide standards. For blind spikes of fruit and vegetable extracts, the database suggested 22 of 26 spiked pesticides as matches. Nineteen were identified by GC/MS. The combination of retention time locking, GC-AED, database search, and GC/MS can be a powerful tool for identifying pesticides in a complex matrix
Determination of Selenium in Meat Products by Hydride Generation Atomic Absorption Spectrophotometry
Authors: Tinggi Ujang 
Published: February 2020

Abstract
Wet digestion using a mixture of nitric, sulfuric, and perchloric acids and an aluminum block digester effectively and rapidly decomposed meat samples for selenium determination by hydride generation atomic absorption spectrophotometry. Digestion did not require constant attention by an operator. Selenium recoveries (range, 94-105%) from National Institute ofStandards and Technology standard reference materials and spiked samples were used to validate method accuracy. Coefficients of variation (CVs) of repeatability of in-house reference materials used forprecision study were 6.4 and 5.6%, respectively, for seafood mix and mutton liver. Selenium levels in meat products from Brisbane markets varied widely: 0.042-0.142,0.081- 0.42, and 0.050-0.198 μg/g (wet weight) respectively, for beef, chicken, and pork. Overall, selenium levels in manufactured meat ranged from0.041 to 0.189 fig/g. The levels of selenium foundinthis study were generally lower than those reported in Finland but comparable with those reported in some parts of the United States
Fusarium Mycotoxins in Corn and Corn Products in a High-Risk Area for Gastric Cancer in Shandong Province, China
Authors: Groves Frank D , Zhang Lian , Chang Yun-Sheng , Ross Frank P , Casper Howard , Norred William P , You Wei-Cheng , Fraumeni Joseph F 
Published: February 2020

Abstract
Consumption of fermented, but not unfermented, corn pancakes has been linked with elevated stomach cancer mortality rates in rural Linqu County in Shandong Province, China. Previous surveys of fungal contamination of corn in China have detected fumonisins, which are mycotoxins produced by Fusarium moniliforme. To determine whether mycotoxins might account for the increased risk of cancer among those consuming fermented pancakes, we obtained specimens of corn, cornmeal, unfermented and fermented pancake batter, and cooked fermented pancakes from each of 16 households in Linqu County for analysis by the U.S. Department of Agriculture. Fumonisins Bi, B2, and B3 were detected (≤0.5 μg/g) in 19,25, and 6% of the corn specimens, respectively, as well as in various corn products. No type A trichothecenes were detected; however, the type B trichothecenes deoxynivalenol and 15-acetyldeoxynivalenol were detected (≤0.5 μg/g) in 58 and 17% of the corn specimens, respectively, and zearalenone was detected (≤0.5 iig/g) in 15% of the cornmeal specimens. The mycotoxins were detected only at low levels (&lt;10 μg/g), which did not increase with fermentation. These findings do not support the hypothesis that mycotoxin contamination increases the risk of gastric cancer among those who consume fermented Chinese pancakes.
An Immunoaffinity Column for the Determination of Peanut Protein in Chocolate
Authors: Newsome Harvey W , Abbott Michael 
Published: February 2020

Abstract
An immunoaffinity column was prepared from rabbit polyclonal antiserum for the determination of peanut protein from food matrixes. The anti-peanut immunoglobulin G was isolated from antiserum by affinity chromatography on a column coupled with peanut protein and then attached to an AminoLink gel. The column was applied to the determination of peanut protein in chocolate after extraction, immunoaffinity chromatography, and enzyme-linked immunosorbent assay (ELISA). Overall recoveries from chocolate spiked with 0.2–3.2 μg/g of peanut protein averaged 77% (range, 72–84%), and the minimum detection limit was 0.1 μg/g. Chromatography of extracts with the column improved detection limit and eliminated the matrix effect experienced with direct ELISA of chocolate extracts.
Determination of Iron in Raw Materials, During Fabric Processing, and in Wastewaters of the Textile Industry
Authors: Grabaric Zorana , Bokic Ljerka , Stefanovic Branka 
Published: February 2020

Abstract
The Schiff base 2-(2-pyridylmethyieneamino)phenol (PMAP) was investigated as a spectrophotometric reagent for determination of iron in caustic soda, cotton yarn and fabric, woolen fabric, and industrial water. The solution properties of Fe(III)-PMAP complexes were determined. At pH 4.4 and 5.6, Fe(III) forms stable complexes with PMAP, with molar absorption coefficients (ε) of 3.00 × 103 and 7.44 × 103/M.cm, respectively. Composition and cumulative stability constants were determined by the mole ratio method (MRM) and the mole fraction variation method (MFVM). At the lower pH (4.4), the predominant complex species in the solution obtained with both methods are ML2, with fairly good agreement of stability constants: log βML2 = 7.00 ± 0.04 with MRM and 7.31 ± 0.01 with MFVM. At the higher pH (5.6), the composition and stability constants of predominant complex species in the solution obtained with the 2 methods were not in good agreement, perhaps because of the coexistence of several species, such as Fe-PMAP, Fe-hydroxo, and Fe-acetate complexes. PMAP is a sensitive reagent for determination of Fe(III). The detection limit of 0.4 μg/mL is lower than those of other frequently used spectrophotometric reagents for Fe. The reagent is ecologically more acceptable, because extraction with organic solvents is avoided. All measurements were made at pH 5.6 because sensitivity was higher at this pH. The high Fe values obtained for industrial water (31.8 μg/mL) indicate that some modifications in the process have to be done. Concentration of Fe in wastewater was much lower (15.9 μg/mL). The results for cotton and woolen fabric indicate that accumulation of Fe in wool is much higher than in cotton (84.4 μg/mL and 29.3-53.1 μg/mL, respectively).
Bayesian Approach to Establishing Assay Limits
Authors: Varbanov Alexandre , Mowrey Daniel 
Published: February 2020

Abstract
A Bayesian method to establishing assay limits of detection and quantitation is proposed. It allows prior knowledge to be incorporated into the analysis of the limits. The posterior distributions of the limits in x (concentration) can be approximated well with the help of a simple simulation procedure. This allows good estimates of mean, variance, and other characteristics of those distributions to be computed. The approach is illustrated by an example with 2 made-up data sets.
Rapid and Simple Determination of Oxytetracycline in Chicken Products
Authors: Furusawa Naoto 
Published: February 2020

Abstract
A rapid and simple method for determining resid ual oxytetracycline (OTC) in chicken products(muscle, liver, and eggs) by high-performance liquid chromatography (HPLC) was developed. Samples were prepared by homogenization with acetonitrile-n-hexane (5 + 4, v/v) followed by centrifugation to minimize fat and protein contents. OTC in the acetonitrile layer was free from interfering compounds when examined by HPLC using a LiChrospher 100 RP-8 end-capped column, a mobile phase of acetonitrile–acetic acid–0.01 M disodium EDTA(28 + 2 + 70, v/v/v),and a photodiode array detector. Average recoveries from samples spiked with OTC (0.1, 0.2, and1.0 ppm) were &gt;88%, with coefficients of variation between 2.3 and 5.1 %. The limit of detection was 0.05 ppm.
Application of Microbial Receptor Assay to Quantitation of Residues of Spectinomycin in Bovine Milk and Comparison with Liquid Chromatographic Analysis
Authors: Shaikh Badar , Schermerhorn Pat , Adam Laura A , Von Bredow Jurgen D 
Published: February 2020

Abstract
Spectinomycin-contaminated bovine milk samples were assayed by liquid chromatographic (LC) and microbial receptor methods. LC involved a newly developed analytical method to quantitate the concentration of spectinomycin in the contaminated milk samples. The receptor assay used reagents and the reaction system used for the Charm II spectinomycin assay. Three standard curves (selected range, full range, and second-order polynomial) were plotted for the receptor assay and used to quantitate spectinomycin in contaminated milk samples. The levels of spectinomycin obtained by the receptor assay, using only the standard curve in the selected range, were comparable to the results obtained by LC analysis.
Confirmation of Azaperone and Its Metabolically Reduced Form, Azaperol, in Swine Liver by Gas Chromatography/Mass Spectrometry
Authors: Adam Laura A 
Published: February 2020

Abstract
The method described confirms the use of the tranquilizer azaperone by detecting the parent compound and the metabolically reduced form, azaperol. Both are confirmed in swine liver at a target concentration of 10 ppb by gas chromatography/mass spectrometry (GC/MS) with electron ionization in the selected-ion-monitoring mode. Swine liver tissue is ground with dry ice. Acetonitrile is added to extract the drug from the tissue. Sodium chloride buffer is added to the extract in preparation for solid-phase extraction (SPE). The aqueous extract is loaded onto an SPE cartridge designed to extract acidic and neutral drug residues from biological matrixes. The cartridge is washed with methanol and conditioned with sodium phosphate buffer. Azaperone and azaperol residues are eluted with a 2% ammonium hydroxide in ethyl acetate. The extracts are evaporated to dryness under a stream of nitrogen and reconstituted in ethyl acetate for GC/MS analysis. A DB-1 analytical column is used to separate the compounds prior to electron ionization. The parent ion, the base peak ion, and one diagnostic fragment ion are monitored for both compounds. The method was validated with fortified tissue samples containing both azaperone and azaperol. Azaperone-incurred tissues also were analyzed, and the presence of the parent drug and the metabolically reduced form, azaperol, was confirmed.
Liquid Chromatographic Detection of Dowtherm A Contamination in Oleochemicals and Edible Oils
Authors: Moh Felix Mee Ho , Tang Thin Sue 
Published: February 2020

Abstract
A rapid and direct liquid chromatographic (LC) technique is described for the determination of a eutectic mixture of diphenyl oxide and biphenyl such as Dowtherm A thermal heating fluid (THF) in oleochemicals and palm olein. Analysis is performed with an RP-18 column with fluorescence detection (excitation at 247 nm and emission at 310 nm). The isocratic mobile phase (1.0 mL/min) consists of methanol and water (90 + 10, v/v). A linear calibration model (correlation coefficient = 0.9999) was developed directly from used Dowtherm A THF with the biphenyl peak (4.70 min) as a marker. Average recoveries from spiked glycerin, fatty alcohol mixture, methyl ester mixture, fatty acids, and palm olein were 90.9–108.7%, with a detection limit of 0.1 μg/mL. The technique requires no prior sample cleanup nor extraction steps and is good for quality assurance purposes.
Electrochemical Determination of Lacidipine
Authors: Squella Juan A , Iribarren Anny E , Sturm Juan C , Núñez-Vergara Luis J 
Published: February 2020

Abstract
Lacidipine is an antihypertensive drug that is oxidizable at the glassy carbon electrode. The voltammetric oxidation of lacidipine in aqueous-alcoholic solutions (70 + 30) produces a well-defined voltammetric peak when subjected to a differential pulse voltammetric experiment. This peak is due to oxidation of the dihydropyridine ring to a pyridine derivative. This voltammetric response result is irreversible, pH dependent, and diffusion controlled. The best resolution for the peak was obtained at pH 6 in Britton-Robinson buffer-ethanol (70 + 30). The peak potential at pH 6 was 800 mV against an Ag-AgCI reference electrode. A linear relationship between peak current and lacidipine concentration was obtained. For analytical purposes, a calibration curve for lacidipine that covered concentrations between 5 x 10-6 and 2 x 10-6 was used. Detection and quantitation limits were 3.52 x 10-6 and 3.78 x 10-6M, respectively. The repeatability of the measurement was 2%. On the basis of the voltammetric response, we also developed high-performance liquid chromatographic methods with electrochemical detection. For comparative purposes, we also developed a spectrophotometric method.
Determination of Residues of Azamethiphos in Salmon Tissue by Liquid Chromatography with Fluorescence Detection
Authors: Pfenning Allen P , Roybal José E , Turnipseed Sherri B , Gonzales Steve A , Hurlbut Jeffrey A 
Published: February 2020

Abstract
A liquid chromatographic (LC) method with fluorescence detection (FLD) is described for determining residues of the pesticide azamethiphos (AZA) in salmon tissue. The sample is extracted with ethyl acetate, centrifuged, dehydrated with anhydrous sodium sulfate, evaporated, reconstituted in water, and defatted with hexane. The aqueous phase is passed through a C18 solid-phase extraction (SPE) column. The SPE column is eluted with methanol, and the eluate is evaporated to dryness and then taken up in 10% acetonitrile (ACN) in water. The analyte is determined by LC using a C18 column, ACN-H2O (32 + 68) mobile phase, and FLD with excitation at 230 nm and emission at 345 nm. Composited salmon tissues were fortified with AZA at 5,10,21, 42, and 83 ng/g or ppb (target level, X = 10 ng/g). Overall recoveries were 86%, with between-day variability of 5.3%. The method detection limit was calculated as 1.2 ppb AZA based on a 5 g sample. The limit of quantitation as determined empirically by this method is the lower limit of the standard curve, approximately 5 ppb.
Determination of Fluoroquinolone Residues in Animal Tissues Using Escherichia coli as Indicator Organism
Authors: Choi Jason , Yee Arlene J , Thompson Dianne , Samoluk Jurek , Mitchell Mark , Black William D 
Published: February 2020

Abstract
Three strains of Escherichia coli(ATCC 128,10536, and 25922) and one strain of Bacillus subtilis (ATCC 3491) were compared as indicator microorganisms in microbial inhibition tests for their ability to detect fluoroquinolone residues. E. coli strains 128 and 10536 were most susceptible to fluoroquinolone residues, with detection limits of 35-50 μg/kg for enrofloxacin. Of the 2 strains, E. coli 10536 was slightly less susceptible. Ciprofloxacin was detected consistently by E. coli 128 at 30 μg/kg. Other fluoroquinolone drugs of veterinary interest detected by E. coli 128 were sarafloxacin and difloxacin at 100-250 μg/kg concentration. E. coli25922 yielded 100% sensitivity in detection of enrofloxacin only at the 250 μg/kg concentration, and ciprofloxacin and sarafloxacin at 200 μg/kg. B. subtilis detected only enrofloxacin 100% of the time at 250 μg/kg. The E. coli strains tested were insensitive to other antibacterials commonly used in animals, with the exception of ceftiofur which was detected by E. coli 128 and 10536 at 500 μg/kg. The B. subtilis strain was not effective in detecting the fluoroquinolone drugs, whereas the E. coli strains were selective for the fluoroquinolones. E. coli 128 was 100% effective in detecting enrofloxacin and ciprofloxacin in spiked diaphragm homogenate samples at 50 μg/kg. Of the microorganisms tested, E. coli strain ATCC 128 was highly suitable as an indicator microorganism in a microbial inhibition assay for selective detection of fluoroquinolone antibacterial residues in animal tissues.
Determination of Hexazinone in Groundwater by Direct-Injection High-Performance Liquid Chromatography
Authors: Perkins L Brian , Bushway Rodney J , Katz Lynn E 
Published: February 2020

Abstract
Hexazinone has been detected at levels ranging from 0.2 to 50 μg/L in many groundwater samples from eastern Maine over the past decade. A rapid and inexpensive direct-injection high-performance liquid chromatographic (HPLC) method has been developed to monitor contamination levels of the herbicide. The method is sensitive (limit of quantitation = 0.33 μg/L) and is linear to 33.0 μg/L (R2 = 0.9995). Direct injection results from 50 field samples compared well (R2 = 0.98) with an HPLC method using solid-phase extraction for concentration and cleanup. The technique is very reproducible (coefficients of variation of 0-8.4% within day and 3.0-13.2% between day) and eliminates loss of analyte because of fewer steps in the procedure.