bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of 10 Sulfonamide Residues in Meat Samples by Liquid Chromatography with Ultraviolet Detection
Authors: Di Sabatino Marcello , Di Pietra Anna Maria , Benfenati Luigi , Di Simone Bruno 
Published: February 2020

Abstract
A liquid chromatography (LC) method is described for the simultaneous determination of 10 commonly used sulfonamide drug residues in meat. The 10 sulfonamide drugs of interest were sulfadiazine, sulfathiazole, sulfamerazine, sulfadimidine, sulfamethizole, sulfamonomethoxine, sulfachloropyridazine, sulfadoxine, sulfadimethoxine, and sulfaquinoxaline. The residues were extracted with acetonechloroform (1 + 1). Sulfonamides were quantitatively retained in the extracting solution and afterwards eluted from a cation-exchanger solid-phase extraction cartridge with a solution of methanolaqueous ammonia. The solution was dried, reconstituted with 5 mL methanol and filtered before analysis by LC-ultraviolet using a C18 column with a mobile phase gradient of potassium dihydrogen phosphate buffer, pH 2.5, and methanolacetonitrile (30 + 70, v/v). The method was applied to cattle, swine, chicken, and sheep muscle tissues. The validation was performed with a fortified cattle meat sample at level of 100 ppb, which is the administrative maximum residue limit for sulfonamides in the European Union. The limit of quantitation for all sulfonamides was between 3 and 14 ppb. Recovery was evaluated for different meat matrixes. The mean recovery values were between 66.3% for pork meat samples and 71.5% for cattle meat samples.
Simultaneous Analysis of Adrenergic Amines and Flavonoids in Citrus Peel Jams and Fruit Juices by Liquid Chromatography: Part 2
Authors: Avula Bharathi , Upparapalli Sampath K , Khan Ikhlas A 
Published: February 2020

Abstract
Citrus species are rich sources for various bioactive compounds such as flavonoids, adrenergic amines, limonoids, and coumarins. Six adrenergic amines and 20 flavonoids in the jams and juices of Citrus species were analyzed by high-performance liquid chromatography with a C18 reversed-phase column using gradient mobile phase of sodium acetate buffer (pH 5.5) and acetonitrile at a flow rate of 1.0 mL/min with detection at 254, 280, and 330 nm. Synephrine was present in levels from 3.65 to 60.66 mg/L in 48 Citrus juices and 0.0181.02 mg per serving in 32 Citrus jams. The content of these amines and flavonoids varied to a large extent depending on the type of the Citrus species used. The method has been successfully applied to the determination of adrenergic amines and flavonoids in several samples of Citrus fruit juices and jams.
Simultaneous Determination of Chlorzoxazone and Ketoprofen in Binary Mixtures and in Ternary Mixtures Containing the Chlorzoxazone Degradation Product by Reversed-Phase Liquid Chromatography
Authors: Hassib Sonia Talaat , Mohammad Mohammad Abdul-Azim , El-Zaher Asmaa A , El-Kady Ehab F 
Published: February 2020

Abstract
New, simple, rapid, and precise reversed-phase high-performance liquid chromatographic (LC) methods were developed for the simultaneous determination of chlorzoxazone (CH) and ketoprofen (KT) in binary mixtures and in ternary mixtures containing the CH degradation product, 2-amino-4-chlorophenol (CD). The analytes were separated by LC on a Lichrosphere&lt;sup/&gt; 60 C18 column (250 4 mm, 5 m). The mobile phases, methanolwater (40:60, v/v) at 1 mL/min and methanol0.05% phosphoric acid (60:40, v/v, pH 2.81) at 1.5 mL/min, satisfactorily resolved the binary and ternary mixtures, respectively. The UV detector was operated at 280 nm for the determination of CH and at 254 nm for the determination of KT and CD. Linearity, accuracy, and precision were found to be acceptable over the concentration ranges of 20240 and 560 g/mL for CH and KT, respectively, in the binary mixtures and 50300, 1060, and 20160 g/mL for CH, KT, and CD, respectively, in the ternary mixtures. The optimized methods proved to be specific, robust, and accurate for the quality control of CH and KT in pharmaceutical preparations.
Estimation of Atorvastatin Calcium and Fenofibrate in Tablets by Derivative Spectrophotometry and Liquid Chromatography
Authors: Nakarani Naresh V , Bhatt Kashyap K , Patel Rutva D , Bhatt Hemaxi S 
Published: February 2020

Abstract
Two simple and accurate methods to determine atorvastatin calcium (ATO) and fenofibrate (FEN) in combined dosage forms were developed using second-derivative spectrophotometry and reversed-phase liquid chromatography (LC). ATO and FEN in combined preparations (tablets) were quantitated using the second-derivative responses at 245.64 nm for ATO and 289.56 nm for FEN in spectra of their solution in methanol. The calibration curves were linear [correlation coefficient (r) = 0.9992 for ATO and 0.9995 for FEN] in the concentration range of 315 g/mL for ATO and FEN. In the LC method, analysis was performed on a Hypersil ODS-C18 column (250 mm 4.6 mm id, 5 m particle size) in the isocratic mode using the mobile phase methanol-water (90 + 10, v/v), adjusted to pH 5.5 with orthophosphoric acid, at a flow rate of 1 mL/min. Measurement was made at a wavelength of 246.72 nm. Both drugs were well resolved on the stationary phase, and the retention times were 1.95 min for ATO and 5.50 min for FEN. The calibration curves were linear (r = 0.9985 for ATO and 0.9976 for FEN) in the concentration range of 315 g/mL for ATO and FEN. Both methods were validated, and the results were compared statistically. They were found to be accurate, precise, and specific. The methods were successfully applied to the estimation of ATO and FEN in combined tablet formulations.
A Rapid Method Based on Hot Water Extraction and Liquid ChromatographyTandem Mass Spectrometry for Analyzing Tetracycline Antibiotic Residues in Cheese
Authors: Bogialli Sara , Coradazzi Cristina , Di Corcia Antonio , Lagana Aldo , Sergi Manuel 
Published: February 2020

Abstract
A rapid, specific, and sensitive procedure for determining residues of 4 widely used tetracycline antibiotics and 3 of their 4-epimers in cheese is presented. The method is based on the matrix solid-phase dispersion (MSPD) technique followed by liquid chromatography/tandem mass spectrometry (LC/MS/MS). After dispersing samples of mozzarella, asiago, parmigiano, gruyere, emmenthal, and camembert on sand, target compounds were eluted from the MSPD column by passing through it 6 mL water heated at 70C. After acidification and filtration, 200 L of the aqueous extract was directly injected into the LC column. For analyte identification and quantification, MS data acquisition was performed in the multireaction monitoring mode, selecting 2 precursor ion-to-product ion transitions for each target compound. Hot water appeared to be an efficient extractant, because absolute recoveries were no lower than 78%. Using demeclocycline as a surrogate analyte, recoveries of analyte added to the 6 types of cheeses at the 30 ng/g level were 96117%, with relative standard deviation (RSD) not higher than 9%. Statistical analysis of the mean recovery data showed that the extraction efficiency was not dependent on the type of cheese analyzed. This result indicates that this method could be applied to other cheese types not considered here. At the lowest concentration considered, i.e., 10 ng/g, the accuracy of the method ranged between 90 and 107%, with RSDs not larger than 12%. Based on a signal-to-noise ratio of 10, limits of quantitation were estimated to be 12 ng/g.
Application of Low-Pressure Gas Chromatography/Tandem Mass Spectrometry to the Determination of Pesticide Residues in Tropical Fruits
Authors: Martnez Vidal Jos Luis , Fernndez Moreno Jos Luis , Arrebola Libanas Francisco Javier , Frenich Antonia Garrido 
Published: February 2020

Abstract
A multiresidue method has been developed for determining pesticide residues in the tropical fruits kiwi, custard apple, and mango. The intended purpose of the method is for regulatory analyses of commodities for pesticides that have established maximum residue limits. A fast and simple extraction method with cyclohexaneethyl acetate (1 + 1, v/v) and a high-speed homogenizer was optimized. Pressurized liquid extraction was evaluated as an alternative automated extraction technique. The pesticide residues were determined by using low-pressure gas chromatography coupled to tandem mass spectrometry. The proposed methodology was validated for each matrix. Pesticide recoveries ranged from 70 to 110%, with repeatability relative standard deviations of 18% at spiking levels of 12 and 50 g/kg. The limits of quantitation were in the range of 0.036.17 g/kg, and the limits of detection were between 0.01 and 3.75 g/kg. Mango can be selected as a representative matrix for calibration on the basis of the results of a potential matrix effect study. The method was successfully applied to the determination of pesticide residues in real samples in Spain.
Development and Validation of a Liquid Chromatography Method for Quantification of Xanthorrhizol in Roots of Iostephane heterophylla (Cav.) Benth ex Hemsl
Authors: Aguilar Mara Isabel , Osorio Nadia , Bernal Israel , Navarrete Andrs , Bye Robert 
Published: February 2020

Abstract
Roots of Iostephane heterophylla (Cav.) Benth ex Hemsl are used mainly in Mexican traditional medicine to heal skin problems. The development of a column high-performance liquid chromatography (LC)-UV detector method for the determination of xanthorrhizol, the major and active component of the roots of I. heterophylla, is described in this paper. The content of this compound was quantitatively determined employing a Symmetry&lt;sup/&gt; C18 5 m particle size column with the isocratic mobile phase acetonitrilewater (85 + 15). The flow rate was 1.0 mL/min, and UV detection was at 230 nm. The limits of detection and quantitation were 0.2 and 0.5 g/mL, respectively. Quantities of xanthorrhizol measured by this method ranged between 1.8 to 10.94 mg/g of root of the plant in 11 different samples of I. heterophylla. Xanthorrhizol was not detected in a sample of I. madrensis, so xanthorrhizol could be used as a marker compound of I. heterophylla. The LC method described here was shown to be reliable, reproducible, and accurate.
Determination of Caffeine and Caffeine-Related Metabolites in Ephedra-Containing Standard Reference Materials Using Liquid Chromatography with Absorbance Detection and Tandem Mass Spectrometry
Authors: Thomas Jeanice B , Sharpless Katherine E , Mitvalsky Staci , Roman Mark , Yen James , Satterfield Mary B 
Published: February 2020

Abstract
The concentrations of caffeine and caffeine-related compounds in 2 ephedra-containing reference materials have been determined by 3 independent methods with measurements performed by the National Institute of Standards and Technology (NIST) and a collaborating laboratory. Results from the 3 methods were used for value assignment of caffeine, theobromine, and theophylline in these Standard Reference Materials (SRMs). The methods used at NIST to determine the concentration levels of caffeine, theobromine, and theophylline in SRM 3243 Ephedra-Containing Solid Oral Dosage Form and SRM 3244 Ephedra-Containing Protein Powder used reversed-phase liquid chromatography with absorbance detection and tandem mass spectrometry. These reference materials are part of the first suite in a series of NIST SRMs that provide concentration values for multiple components in dietary supplements. These SRMs are primarily intended for method validation and for use as control materials to support the analysis of dietary supplements and similar materials.
Simultaneous Separation of 14 Antiarrhythmic Drugs and Determination of Mexiletine and Flecainide by Capillary Zone Electrophoresis
Authors: Pietra Rafal , Kowalczuk Dorota , Hopkala Hanna 
Published: February 2020

Abstract
A method using capillary zone electrophoresis was developed for the simultaneous separation of 14 antiarrhythmic drugs belonging to various classes. The drugs are separated on a fused-silica capillary, 90 cm 75 m (72 cm effective length), with phosphate and acetate buffers as background electrolytes and UV detection at 217 nm. The effects of buffer pH, temperature, and applied voltage on the migration of the drugs were studied. The pH was found to be the most significant factor determining effective separation. The antiarrhythmic compounds are completely separated within a relatively short time (&lt;7 min) by using 70 mM phosphate buffer at pH 7.91, an applied voltage of 28 kV, and a temperature of 32C. Mexiletine (MEX) and flecainide (FLE) were quantified under conditions of the optimum separation. The calibration graphs were constructed over the concentration range of 4.014.0 g/mL for both drugs with good correlation (r 0.9999). Detection and quantitation limits were found to be 0.5 and 1.5 g/mL for FLE and 0.7 and 2.1 g/mL for MEX, respectively. The proposed method was used for the determination of both drugs in their commercial forms with satisfactory precision (relative standard deviations of 0.361.21% for FLE and 0.781.66% for MEX) and accuracy (relative standard errors of 0.131.17% for FLE and 0.351.18% for MEX).
Analysis of Flavonol Aglycones and Terpenelactones in Ginkgo biloba Extract: A Comparison of High-Performance Thin-Layer Chromatography and Column High-Performance Liquid Chromatography
Authors: Gray Dean E , Messer Dale , Porter Andrew , Hefner Brian , Logan Dama , Harris Roger K , Clark Alice P , Algaier Joseph A , Overstreet J Diane , Smith Cynthia S 
Published: February 2020

Abstract
Advancements in automated high-performance thin-layer chromatography (HPTLC) have made it feasible to assess its use for the quantitative analysis of marker compounds in botanical preparations. We report here the findings of method comparisons for the terpenelactones and flavonol aglycones by column high-performance liquid chromatography (HPLC) with evaporative light scattering and UV detection, and HPTLC with a scanning densitometer. For the HPTLC assay of terpenelactones, total bilobalide, ginkgolide A, and ginkgolide B consistently achieved &lt;70 of the total determined using HPLC, regardless of variations to postchromatographic derivatization time and temperature. Accuracy testing showed the possibility of a matrix interference. In contrast, a good relationship (95) was determined between HPTLC and HPLC for determination of total flavonol glycosides (calculated from combined quercetin, kaempferol, and isorhamnetin) from an acid-hydrolyzed Ginkgo biloba L. (GBE) sample. The HPTLC flavonol aglycone method also performed well in terms of accuracy (overall average of 96 recovery for the 3 aglycones) and consecutive plate repeatability (overall percent relative standard deviation of 4.4). It is demonstrated that HPTLC can be a time-saving complement to HPLC for routine analysis of the flavonol glycosides in GBE.
Extractive Spectrophotometric Methods for Determination of Zolmitriptan in Tablets
Authors: Aydogmus Zeynep , Inanli Ipek 
Published: February 2020

Abstract
Two simple and sensitive extractive spectrophotometric methods have been developed for determination of zolmitriptan (ZTP) in tablets. These methods are based on the formation of yellow ion-pair complexes between ZTP and tropaeolin OO (TPOO) and bromothymol blue (BTB) in citratephosphate buffer of pH 4.0 and 6.0, respectively. The formed complexes were extracted with dichloromethane and measured at 411.5 and 410 nm for TPOO and BTB, respectively. The best conditions of the reactions were studied and optimized. Beer's law was obeyed in the concentration ranges of 220 and 1.517 g/mL with molar absorptivities of 1.42 104 and 1.60 104 L/mol/cm for the TPOO and BTB methods, respectively. Correlation coefficients were 0.9998 and 0.9999 for TPOO and BTB methods, respectively. Limits of detection of the TPOO and BTB methods were 0.341 and 0.344 g/mL, respectively, and the limits of quantitation were 1.034 and 1.051 g/mL, respectively. Sandell's sensitivity and stability constant were also calculated. The proposed methods have been applied successfully for the analysis of the drug in its dosage forms. No interference was observed from excipients present in tablets. Statistical comparison of the results with those obtained by a high-performance liquid chromatography method showed excellent agreement and indicated no significant differences in accuracy and precision.
Monitoring Stevioside in Soju by High-Performance Liquid Chromatography and Liquid Chromatography/Mass Spectrometry
Authors: Ni Fan , Ammann Jeffrey , Mabud Abdul 
Published: February 2020

Abstract
A method using high-performance liquid chromatography (HPLC) with UV absorption detection was developed to monitor stevioside in soju, a distilled spirits product that is commercially available. The method uses a single-step dilution for sample preparation. It completely eliminates the time-consuming process of solid-phase extraction. A method using HPLC/mass spectrometry was optimized to confirm the identities of stevioside and other related impurities, including rebaudioside A, rebaudioside C, and dulcoside. The method was validated. The validation parameters included range (10.11007.3 ppm), precision, linearity, accuracy, robustness, system suitability, and intermediate precision. Stevioside standard solutions at 6 concentration levels were prepared for the validation work, including the tests for precision, linearity, and accuracy. The solutions were prepared in triplicate for each concentration. The relative standard deviation for the precision test was &lt;3 for all 6 concentration levels. The correlation coefficient for the linearity within the concentration range was determined to be &gt;0.999. The average recovery ranged from 95.7 to 101.1 for the soju samples spiked with stevioside standard. The detection limit for stevioside was estimated at 75 ppb. The method was used to screen several soju samples; no detectable stevioside was found in the samples.
Microbiological Assay for Ceftazidime Injection
Authors: Moreno Andréia De Haro , Salgado Hérida Regina Nunes 
Published: February 2020

Abstract
A simple, sensitive, and specific biodiffusion assay for the antibacterial ceftazidime was developed using a strain of Staphylococcus epidermidis (ATCC 12228) as the test organism. Ceftazidime was measured in powder for injection at concentrations ranging from 100 to 400 g/mL. The calibration graph for ceftazidime was linear (r2 = 1), and the method validation showed that it was precise (relative standard deviation = 0.415) and accurate. The results obtained by biodiffusion assay were statistically calculated by linear parallel model and by means of regression analysis and were verified using analysis of variance. It was concluded that the microbiological assay is satisfactory for in vitro quantification of the antibacterial activity of ceftazidime in pharmaceuticals.
Evaluating Measurement Uncertainty in the Microbiological Assay of Vancomycin from Methodology Validation Data
Authors: Lourenço Felipe Rebello , Kaneko Telma Mary , Pinto Terezinha De Jesus Andreoli 
Published: February 2020

Abstract
Methodology validation and measurement uncertainty estimation are fundamental to obtain reliable results. The microbiological methods are widely used to determine antibiotic assay, as they permit evaluation of the analyzed antibiotic activity. A microbiological assay of vancomycin was performed with adoption of experimental design 5 1 (interpolation in 5-point standard curve assay) with final concentrations from 6.4 to 15.6 g/mL (standards) and 10.0 g/mL (sample). Bacillus subtitlis (ATCC 6633) was the microorganism used, with antibiotic medium No. 8 as base layer and inoculated layer. The plates were incubated at 37C for 18 h. The method adopted for the microbiological assay of vancomycin through agar diffusion was validated according to statistic results demonstrated for suitability of the method concerning linearity, precision, and accuracy. The estimated relative expanded uncertainty (4.3) was considered adequate for this method purpose.
Overaccumulation of Higher Polyamines in Ripening Transgenic Tomato Fruit Revives Metabolic Memory, Upregulates Anabolism-Related Genes, and Positively Impacts Nutritional Quality
Authors: Mattoo Autar K , Chung Sang Ho , Goyal Ravinder K , Fatima Tahira , Solomos Theophanes , Srivastava Alka , Handa Avtar K 
Published: February 2020

Abstract
Vegetables and fruits are essential components of the human diet as they are sources of vitamins, minerals, and fiber and provide antioxidants that prevent chronic diseases. Our goal is to improve durable nutritional quality of tomato fruit. We developed transgenic tomatoes expressing yeast S-adenosylmethionine decarboxylase (ySAMdc) gene driven by a fruit-specific E8 promoter to investigate the role of polyamines in fruit metabolism. Stable integration of E8-ySAMdc chimeric gene in tomato genome led to ripening-specific accumulation of polyamines, spermidine (Spd) and spermine (Spm), which in turn affected higher accumulation of glutamine, asparagine, and organic acids in the red fruit with significant decrease in the contents of valine, aspartate, sucrose, and glucose. The metabolite profiling analysis suggests that Spd/Spm are perceived as signaling organic-N metabolites by the fruit cells, resulting in the stimulation of carbon sequestration; enhanced synthesis of biomolecules; increased acid to sugar ratio, a good attribute for the fruit flavor; and in the accumulation of another vital amine, choline, which is an essential micronutrient for brain development. A limited transcriptome analysis of the transgenic fruit that accumulate higher polyamines revealed a large number of differentially expressed genes, about 55 of which represented discrete functional categories, and the remaining 45 were novel, unknown, or unclassified: amino acid biosynthesis, carotenoid biosynthesis, cell wall metabolism, chaperone family, flavonoid biosynthesis, fruit ripening, isoprenoid biosynthesis, polyamine biosynthesis, signal transduction, stress/defense-related, transcription, translation, and vacuolar function. There was a good correspondence between some gene transcripts and their protein products, but not in the case of the tonoplast intrinsic protein, which showed post-transcriptional regulation. Higher metabolic activity of the transgenic fruit is reflected in higher respiratory activity, and upregulation of chaperones and mitochondrial cytochrome oxidase transcripts compared to the control. These transgenic plants are a new resource to understand the role of Spd/Spm in fruit biology. Transcriptome analysis and metabolic profiles of Spd/Spm accumulating, transgenic fruit suggest the presence of an intricate regulation and interconnection between certain metabolic pathways that are revived when Spd and Spm likely reach a certain threshold. Thus, polyamines act as antiapoptotic regulatory molecules and are able to revive metabolic memory in the tomato fruit.