bluuebunny/crossref_metadata_2025_split huggingface dataset:
Method for the Determination of Aconitum Alkaloids in Dietary Supplements and Raw Materials by Reversed-Phase Liquid Chromatography with Ultraviolet Detection and Confirmation by Tandem Mass Spectrometry: Single-Laboratory Validation
Authors: Tang Wai-Tong , Wong Sui-Kay , Law Tin-Yau , Pang Kwok-Chu , Sin Della , Tam Yin-King 
Published: February 2020

Abstract
A study of single-laboratory validation (SLV) of a reversed-phase liquid chromatography (RP-LC) method was conducted for the determination of diester-diterpene Aconitum alkaloids, viz., aconitine, mesaconitine, and hypaconitine, in a variety of dietary supplements, including single-and multiple-ingredient dry powder extracts, pills, capsules, and raw materials. The Aconitum alkaloids in the samples were extracted by diethyl ether in the presence of ammonia. After cleanup with solid-phase extraction to remove the matrix interferences, the alkaloids were determined by RP-LC with UV detection at 235 nm, and the results were confirmed by tandem mass spectrometry. The linear responses for aconitine, mesaconitine, and hypaconitine based on the present LC system ranged from 0.5 to 200 μg/mL. Relative standard deviations of 2.0 to 6.9% were obtained from duplicate analysis of 6 test materials of different matrixes for the 3 Aconitum alkaloids performed by 2 analysts on 5 different days. The recoveries determined for supplements and raw materials spiked with 3 Aconitum alkaloids at levels of 2.5-10 μg/g were in the range of 86-99%. In view of the attainment of satisfactory results for accuracy, precision, and recovery in the SLV study, it is recommended that the method validation process proceed to a collaborative study.
Spectrophotometric Stability-Indicating Methods for the Determination of Leflunomide in the Presence of Its Degradates
Authors: Abbas Samah S , Bebawy Lories I , Fattah Laila A , Refaat Heba H 
Published: February 2020

Abstract
Five simple and sensitive methods were developed for the determination of leflunomide (I) in the presence of its degradates 4-trifluoromethyl aniline (II) and 3-methyl-4-carboxy isoxazole (III). Method A was based on differential derivative spectrophotometry by measuring the △1D value at 279.5 nm. Beer's law was obeyed in the concentration range of 2.0020.00 μg/mL with mean percentage accuracy of 100.07 1.32. Method B depended on first-derivative spectrophotometry and measuring the amplitude at 253.4 nm. Beer's law was obeyed in the concentration range of 2.0016.00 μg/mL with mean percentage accuracy of 98.42 1.61. Method C was based on the reaction of degradate (II) with 2,6-dichloroquinone-4-chloroimide (Gibbs reagent). The colored product was measured at 469 nm. Method D depended on the reaction of degradate (II) with para-dimethyl aminocinnamaldehyde (p-DAC). The absorbance of the colored product was measured at 533.4 nm. Method E utilized 3-methyl-2-benzothiazolinone hydrazone in the presence of cerric ammonium sulfate with degradate (II). The green colored product was measured at 605.5 nm. The linearity range was 40.00-280.00, 2.40-24.00, and 30-250 μg/mL with mean percentage accuracy of 100.75 1.21, 100.13 1.45, and 99.74 1.39 for Methods CE, respectively. All variables were studied to optimize the reaction conditions. The proposed methods have been successfully applied to the analysis of leflunomide in pharmaceutical dosage forms and the results were statistically compared with that previously reported.
Determination of Nucleic Acids Using Fluorescence Probe Sensitized by Microemulsion
Authors: Wei Qin , Zhang Hui , Du Bin , Duan Caihong 
Published: February 2020

Abstract
Because the fluorescence of azur A can be quenched by adding nucleic acid, a sensitive fluorometric method for determination of nucleic acids at nanogram levels was established. Using optimal conditions, the calibration curves were linear in the range of 06.0 μg/mL for calf thymus deoxyribonucleic acid (ct DNA) and 07.0 μg/mL for herring sperm DNA (hs DNA). The limits of determination were 3.5 and 3.8 ng/mL, respectively, which shows the high sensitivity of this method. Triton X-100 microemulsion was applied as a sensitive media to enhance the sensitivity. The binding mode concerning the interactions of azur A with nucleic acids was also studied and the association constant with different binding numbers was obtained. The method has been applied to the determination of nucleic acid in both synthetic and real samples, such as cauliflower and pork liver, with satisfactory results.
Determination of Forchlorfenuron Residues in Watermelon by Solid-Phase Extraction and High-Performance Liquid Chromatography
Authors: Hu Ji-Ye , Li Jian-Zhong 
Published: February 2020

Abstract
A method using solid-phase extraction for cleanup, followed by high-performance liquid chromatography with ultraviolet detection (HPLC/UV), was developed for the determination of forchlorfenuron residues in watermelon. The pesticide is extracted from the sample with acidic acetonitrile, and the extract is loaded onto a primary-secondary amine (PSA) column. The pesticide is eluted with acetone and determined by HPLC/UV. The PSA column was found to provide effective cleanup, removing the greatest number of sample matrix interferences. The acetonitrile extraction followed by the PSA cleanup provided recoveries of &gt;95%, coefficients of variation (precision) of &lt;10%, and sensitivity of 0.005 mg/kg, in agreement with the directives for method validation in residue analysis. The proposed method was successfully used to determine forchlorfenuron residue levels and dissipation rates in watermelon grown in an experimental greenhouse in Beijing, People's Republic of China.
Development of Extraction and Gas Chromatography Analytical Methodology for Cyanogenic Glycosides in Flaxseed (Linum usitatissimum)
Authors: Bacala Ray , Barthet Véronique 
Published: February 2020

Abstract
The development of well-characterized rapid methodology for the extraction and gas chromatographic analysis of the cyanogenic glycosides linustatin and neolinustatin from flaxseed (Linum usitatissimum L.) is reported. Two quantitation methods using phenyl-β-d-glucopyranoside as an internal standard are described: direct quantitation using linustatin and neolinustatin external standard curves standard curve slope variabilities of 2.6 and 5.7% relative standard deviation (RSD), respectively, over 7 days or by use of methyl-α-d-glucopyranoside as a surrogate external standard, with conversion factors to convert to linustatin and neolinustatin concentration 1.109 ± 0.015 (SD) mg linustatin/mg methyl-α-d-glucopyranoside and 1.180 ± 0.067 (SD) mg neolinustatin/mg methyl-α-d-glucopyranoside. The former method is direct, thereby contributing less uncertainty to the method, and the latter adds a small degree of uncertainty coupled with considerable cost savings. Limits of detection for all standards were in the low- to sub-nanogram level and were 10-100 times lower than the lower limit of quantitation (LOQ). Repeatability precision was performed on 2 separate days at the lower and upper LOQs, with the RSD in peak response being 1% or lower in all cases. Extraction methods were evaluated for their ability to extract linustatin and neolinustatin from flaxseed using several combinations of aqueous ethanol, and recoveries were determined against the highest yielding method. Recoveries were as low as 82%, indicating that optimized extraction methodology is critical for the accuracy of results.
Determination of Patulin in Apple Juice: Comparative Evaluation of Four Analytical Methods
Authors: Katerere David R , Stockenström Sonja , Balducci Gabriele , Shephard Gordon S 
Published: February 2020

Abstract
The performance of 4 purification methods for the analysis of patulin in apple juice was evaluated by high-performance liquid chromatography (HPLC). Samples were spiked with patulin at 10, 20, 50, 100, and 150 ppb (ng/mL) and extracted by one of 4 methods (3 solid-phase extraction and one liquidliquid extraction), and then analyzed by HPLCUV under the same isocratic conditions. The methods were validated for recovery, linearity, and precision at high and low concentrations. Recoveries were all &gt;70% for spiking range 10-150 ppb. The relative standard deviation for repeatability was found to meet European Union Directive requirements. In addition, all the methods showed baseline separation from hydroxymethylfurfural.
Determination of Organophosphorus Pesticides in Lycium barbarum by Gas Chromatography with Flame Photometric Detection
Authors: Li Li , Liu Fengmao , Qian Chuanfan , Jiang Shuren , Zhou Zhiqiang , Pan Canping 
Published: February 2020

Abstract
An analytical method was developed to determine 14 organophosphorus pesticide residues in Lycium barbarum, which is both a botanical medicine and a food. A 5 g sample is mixed with 10 mL ethyl acetate and, after shaking and centrifuging, 5 mL of the upper layer is removed, concentrated, and analyzed by gas chromatography (GC) with flame photometric detection. The essential feature of this method is that, for the purpose of reducing the burden of the GC system, 0.01 g activated carbon is used to absorb pigments during the cleanup procedure. Average recoveries of 14 organophosphorus pesticides added at 0.05, 0.1, and 0.5 mg/kg were 66.84-102.42, 71.07-97.93, and 62.50-96.24%, respectively. Limits of detection ranged from 5 to 15 μg/kg. The identities of the 14 pesticides were confirmed by GC/mass spectrometry detection in the selected-ion monitoring mode. This method is sensitive, simple, rapid, inexpensive, and safe.
Computational Models for Structure-Hydrophobicity Relationships of 4-Carboxyl-2,6-Dinitrophenyl Azo Hydroxynaphthalenes
Authors: Idowu Olakunle S , Adegoke Olajire A , Idowu Abiola , Olaniyi Ajibola A 
Published: February 2020

Abstract
Some phenyl azo hydroxynaphthalene dyes (e.g., sunset yellow) are certified as approved colorants for food, cosmetics, and drug formulations. The hydrophobicity of 4 newly synthesized azo dyes of the phenyl azo hydroxynaphthalene class was investigated, as a training set, with the goal of developing models for quantitative structureproperty relationships (QSPR). Retention behavior of the molecules reversed-phase thin-layer chromatography (RPTLC) was investigated using liquid paraffin-coated silica gel as the stationary phase. Mobile phases consisted of aqueous mixtures of methanol, acetone, and dimethylformamide (DMF). Basic hydrophobicity parameter (Rmw), specific hydrophobic surface area (S), and isocratic chromatographic hydrophobicity index (o) were computed from the chromatographic data. The hydrophobicity index (Rm) decreased linearly with increasing concentration of organic modifiers. Extrapolated Rmw values obtained by using DMF and acetone differ significantly from the value obtained by using methanol as organic modifier P &lt; 0.05, 1-way analysis of variance (ANOVA), Tukey's multiple comparison test. Structureproperty relationships showed that hydrophobicity was dependent on type and position of naphthalene ring substituents. Rm decreased with the presence of a highly polar substituent (e.g., COOH). Owing to intramolecular interaction, Rm increased when the common hydroxyl group (OH) is positioned ortho to the azo group, relative to para positioning, in 2 positional isomers. Pattern recognition data analysis underscores the utility of φo as a more accurate hydrophobicity descriptor than Rmw. φo is negatively correlated with theoretically calculated density, surface tension, and refractive index for the molecules. These models could be used to predict toxicity (absorption, distribution, metabolism, excretion, toxicity; ADMET) properties of the azo dyes and may also play useful roles in computer-assisted molecular discovery of nontoxic azo dyes.
Determination of the Analgesic Components of Spasmomigraine® Tablet by Liquid Chromatography with Ultraviolet Detection
Authors: Elbarbry Fawzy A , Mabrouk Mokhtar M , El-Dawy Mohamed A 
Published: February 2020

Abstract
A procedure was developed for the determination of the analgesic components of Spasmomigraine® tablets, which are ergotamine (I), propyphenazone (II), caffeine (III), camylofin (IV), and mecloxamine (V). They were subjected to high-performance liquid chromatography on a column (300 × 3.9 mm, 10 μm particle size) packed with μ-Bondapak C18. Separations were achieved with the mobile phase methanol–water–triethylamine (60 + 40 + 0.1, v/v/v) flowing at a rate of 1.5 mL/min, and quantitative determination was performed at 254 nm at ambient temperature for I–III; acetonitrile–25 mM KH2PO4–acetic acid (45 + 55 + 0.2, v/v/v), flowing at a rate of 1.5 mL/min and detection at 234 nm at ambient temperature, was used for IV and V. Methyl paraben was used as an internal standard. The detection limits were 0.35 (I), 5.0 (II), 1.5 (III), 3.0 (IV), and 2.0 g/mL (V). The method was accurate (mean recovery 98 ± 2%, n = 4) and precise (coefficient of variation &lt;5%, n = 5). The proposed method is rapid and sensitive and, therefore, suitable for the routine control of these ingredients in multicomponent dosage forms.
A Validated Quantitative Thin-Layer Chromatographic Method for Estimation of Diosgenin in Various Plant Samples, Extract, and Market Formulation
Authors: Trivedi Priti D , Pundarikakshudu Kilambi , Rathnam Shivprakash , Shah Karishma S 
Published: February 2020

Abstract
A sensitive and reproducible thin-layer chromatographic method has been developed for quantitation of diosgenin, a spiroketal sapogenin. The spots were visualized by spraying with modified anisaldehyde-sulfuric acid reagent. The concentration of anisaldehyde was reduced to 0.1% instead of 1%, and the concentration of sulfuric acid was kept at a minimum of 2%. This successfully reduced charring and background interference. The method was validated according to International Conference on Harmonization guidelines. The method was used for determination of diosgenin from dried samples of fenugreek seeds, leaves, stem, seed extracts, and a polyherbal antidiabetic formulation containing fenugreek powder as one of the ingredients. Increased detection sensitivity was observed with linearity from 98 to 588 ng/spot and a correlation coefficient (r2) of 0.988. The relative standard deviation value for linearity of the method was found to be 0.18%. The method was successfully applied to various plant samples of fenugreek (Methi) with a recovery of 98.11 ± 1.4%. Dried plant samples and a market formulation were analyzed and found to contain diosgenin in the range of 0.5290.658% (w/w) in fenugreek seed powders, 0.087% (w/w) in fenugreek leaf powder, 0.015 and 1.27% (w/w) in fenugreek stem powder and extract, respectively, and 0.586% (w/w) in a formulation containing fenugreek seed powder. No matrix interference was observed.
Application of Derivative, Derivative Ratio, and Multivariate Spectral Analysis and Thin-Layer Chomatography-Densitometry for Determination of a Ternary Mixture Containing Drotaverine Hydrochloride, Caffeine, and Paracetamol
Authors: Metwally Fadia H , El-Saharty Yasser S , Refaat Mohamed , El-Khateeb Sonia Z 
Published: February 2020

Abstract
New selective, precise, and accurate methods are described for the determination of a ternary mixture containing drotaverine hydrochloride (I), caffeine (II), and paracetamol (III). The first method uses the first (D1) and third (D3) derivative spectrophotometry at 331 and 315 nm for the determination of (I) and (III), respectively, without interference from (II). The second method depends on the simultaneous use of the first derivative of the ratio spectra (DD1) with measurement at 312.4 nm for determination of (I) using the spectrum of 40 μg/mL (III) as a divisor or measurement at 286.4 and 304 nm after using the spectrum of 4 μg/mL (I) as a divisor for the determination of (II) and (III), respectively. In the third method, the predictive abilities of the classical least-squares, principal component regression, and partial least-squares were examined for the simultaneous determination of the ternary mixture. The last method depends on thin-layer chromatography-densitometry after separation of the mixture on silica gel plates using ethyl acetatechloroformmethanol (16 + 3 + 1, v/v/v) as the mobile phase. The spots were scanned at 281, 272, and 248 nm for the determination of (I), (II), and (III), respectively. Regression analysis showed good correlation in the selected ranges with excellent percentage recoveries. The chemical variables affecting the analytical performance of the methodology were studied and optimized. The methods showed no significant interferences from excipients. Intraday and interday assay precision and accuracy values were within regulatory limits. The suggested procedures were checked using laboratory-prepared mixtures and were successfully applied for the analysis of their pharmaceutical preparations. The validity of the proposed methods was further assessed by applying a standard addition technique. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by the manufacturer's method.
Column and Thin-Layer Chromatographic Methods for the Simultaneous Determination of Acediasulfone in the Presence of Cinchocaine, and Cefuroxime in the Presence of Its Hydrolytic Degradation Products
Authors: Mohammad Mohammad Abdul-Azim , Zawilla Nagwan H , El-Anwar Fawzy M , El-Moghazy Aly Samir M 
Published: February 2020

Abstract
Column liquid chromatography (LC) and thin-layer chromatography (TLC)densitometry methods are described for simultaneous determination of acediasulfone (Ace) and cinchocaine (Cinco). In the LC method, the separation and quantitation of the 2 drugs was achieved on a Zorbax C8 column (5 μm, 150 × 4.6 mm id) using a mobile phase composed of methanol-phosphate buffer, pH 2.5 (66 + 34, v/v), at a flow rate of 1 mL/min and ultraviolet detection at 300 and 327 nm for Ace and Cinco, respectively. The method showed linearity over concentration ranges of 20-200 and 45685 μg/mL, respectively. In the TLCdensitometry method, a mobile phase composed of methanol-tetrahydrofuran-acetic acid (45 + 5 + 0.5, v/v/v) was used for the separation of the 2 drugs. The linearity range was 0.5-4 and 2-9 μg/spot, respectively. In addition, stability indicating TLCdensitometry method has been developed for determination of cefuroxime sodium in the presence of 570% of its known hydrolytic degradation products. The mobile phase butanol-methanol-tetrahydrofuran-concentrated ammonium hydroxide (50 + 50 + 50 + 5, v/v/v/v) was used. The concentration range was 210 g/spot. The optimized methods proved to be specific and accurate for the analysis of the cited drugs in laboratory-prepared mixtures and dosage forms. The obtained results agreed statistically with those obtained by the reference methods.
Determination of Benzene in Soft Drinks and Other Beverages by Isotope Dilution Headspace Gas Chromatography/Mass Spectrometry
Authors: Cao Xu-Liang , Casey Valerie , Seaman Steve , Tague Brett , Becalski Adam 
Published: February 2020

Abstract
An automated, simple, and reproducible method was developed for the determination of benzene in soft drinks, based on isotope dilution headspace gas chromatography/mass spectrometry in the selected-ion monitoring mode. The method was used to assess benzene levels in samples of 124 soft drinks and beverages. Benzene was not detected in 60% of the 124 products. The average benzene levels in 6 products exceeded the Canadian maximum acceptable concentration of 5 g/L for benzene in drinking water, and 2 of the 6 products had benzene levels above the World Health Organization guideline of 10 g/L. The highest level of benzene, 23 g/L, was found in a soft drink product specifically marketed to children.
Determination of Imazaquin Residues in Soil by Solid-Phase Extraction and High-Performance Liquid Chromatography
Authors: Xuyan Chen , Jiye Hu , Jianzhong Li 
Published: February 2020

Abstract
A method has been developed for the quantitation of imazaquin residues in soil. The herbicide was extracted from soil with methanolwater (2 + 1, v/v) and cleaned up by strong anion-exchange solid-phase extraction cartridges. Analysis was performed by using high-performance liquid chromatography with ultraviolet detection. Average recoveries through the method ranged from 90.7 to 100.6%, with relative standard deviation equal to or lower than 6.6%. The limit of detection was estimated to be 0.0015 mg/kg, and the minimum quantitation concentration of imazaquin in soil was 0.005 mg/kg. This method was successfully applied to evaluate imazaquin residue levels in soil and its dissipation rates in a soybean field in the Xisanqi District of Beijing, People's Republic of China. The dissipation study showed that the half life of imazaquin in soil was 10.37 0.0135 days at 3 different application rates.
Simultaneous Quantitative Determination of the Synthetic Antioxidant Ethoxyquin and Its Major Metabolite in Atlantic Salmon (Salmo salar, L), Ethoxyquin Dimer, by Reversed-Phase High-Performance Liquid Chromatography with Fluorescence Detection
Authors: Berdikova Bohne Victoria J , Hove Helge , Hamre Kristin 
Published: February 2020

Abstract
A method for simultaneous quantitative determination of ethoxyquin (EQ) and its major metabolite in Atlantic salmon tissues, ethoxyquin dimer (EQ dimer), has been developed. The separation was achieved on tandem coupled phenyl-hexyl and C18 columns by 2-phase gradient elution with acetonitrileascorbic acidacetic aciddiethyl amine organized in a 23.5 min sequence. Compounds were extracted with hexane from samples saponified in ethanolNaOH and protected from air- and light-mediated oxidation by addition of saturated ethylenediaminetetraacetic acid, ascorbic acid, and pyrogallol. The identity of peaks was confirmed by spiking samples with standards verified by proton nuclear magnetic resonance spectrometry, mass spectrometry, and high-performance liquid chromatography. The detection limit (at 358/433 nm) of matrix-spiked EQ was 0.02 and 0.06 g/L for EQ dimer, with 0.5 g sample weighed and resuspension in 0.5 mL hexane. Linearity was in the range of 0.2175 g/L for EQ and 0.35100 g/L for EQ dimer. Two more ubiquitous compounds were identified as de-ethylated EQ and quinone imine. Totally, 14 peaks sharing spectral properties of EQ were separated in a single run, including a major peak present in all muscle samples, termed unknown metabolite of EQ (UMEQ). The concentrations of EQ, EQ dimer, and de-ethylated EQ, as well as concentrations of UMEQ (in arbitrary units), in the muscle were correlated to the amount of EQ fed to the salmon, thus indicating their possible metabolic origin. The pattern of 14 peaks in the muscle showed high specificity and could be used to discriminate between wild salmon and salmon fed EQ-supplemented feed. This method will be a useful tool for studying EQ metabolism and kinetics, and for the routine surveillance of residual levels of dietary EQ in farmed Atlantic salmon.