bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Nitrite, Nitrate, and Glucose-6-Phosphate in Muscle Tissues and Cured Meat by IC/MS
Authors: Saccani Giovanna , Tanzi Enrica , Cavalli Silvano , Rohrer Jeff
Published: February 2020

The endogenous nitrate concentration in fresh meat and the residual nitrate and nitrite contents after curing are related to food quality and safety. Most ion chromatography (IC) methods suffer from interferences, especially in fresh meat samples, in which the endogenous nitrate content is low, and in cured meat products, in which other nitrogenous compounds can interfere with the separation of inorganic anions. One of the major classes of interfering compounds in fresh meat are sugar phosphates, which originate from glycolysis during the conversion of muscle glycogen to lactic acid. Nitrate can be separated from interfering compounds with a high-capacity anion-exchange column that was manufactured for use with hydroxide eluents (i.e., hydroxide-selective). This column has a different selectivity than traditional IC columns that use carbonate eluents and facilitates the determination of nitrate in both fresh and cured meats. Nitrate was detected by both suppressed conductivity measurement and mass spectrometry (MS). The identifications of nitrate and glucose-6-phosphate were confirmed by MS detection. The described IC/MS method is robust, sensitive to nitrate concentrations as low as 0.10 mg/kg, and can determine sugar phosphates that are useful for monitoring meat freshness. We successfully used this method to determine nitrate in nearly 100 muscle tissues and cured meat samples.
Improvements to a Surface Plasmon Resonance-Based Immunoassay for the Steroid Hormone Progesterone
Authors: Gillis Els H , Traynor Imelda , Gosling James P , Kane Marian
Published: February 2020

The effects of modifications to an existing protocol for a surface plasmon resonance biosensor-based inhibition immunoassay for progesterone in cow's milk with a sensitivity of 3.5 ng/mL were examined to establish if the detection limit could be further reduced to broaden the potential applications of the assay. The mean relative standard deviation of duplicate measurements was 0.62% and the high precision resulted in very low values for the lower detection limits. Hence, the standard concentrations giving 95% maximum binding [effective dose (ED 95)] were compared instead. The ED 95 was not affected within a running temperature range of 20-37C, or at a flow rate and a contact time above 20 μL/min and 90 s, respectively. Increasing both the absolute sample volume and the antibody dilution improved sensitivity. However, there was a simultaneous reduction in the working range when the assay was applied to milk due to nonspecific binding. Less antibody was associated with large decreases in the maximum binding, but because the high precision extended over a broad analytical range, an ED 95 of 0.4-0.6 ng/mL in milk and 35-60 pg/mL in HBS-EP buffer were achieved. Thus, simple procedural modifications with the same sensor chip can alter performance characteristics of the assay as required for different applications.
Surface Plasmon Resonance for Detection of Genetically Modified Organisms in the Food Supply
Authors: Gambari Roberto , Feriotto Giordana
Published: February 2020

A review is presented demonstrating that biospecific interaction analysis, using surface plasmon resonance (SPR) and biosensor technologies is a simple, rapid, and automatable approach to detect genetically modified organisms (GMOs). Using SPR, we were able to monitor in real-time the hybridization between oligonucleotide or polymerase chain reaction (PCR)-generated probes and target single-stranded PCR products obtained by using as substrates DNA isolated from normal or transgenic soybean and maize. This procedure allows a one-step, nonradioactive detection of GMOs. PCR-generated probes are far more efficient in detecting GMOs than are oligodeoxyribonucleotide probes. This is expected to be a very important parameter, because information on low percentage of GMOs is of great value. Determination of the ability of SPR-based analysis to quantify GMOs should be considered a major research field for future studies, especially for the analyses of food supplies.
Factors Affecting the Bioavailability of Soy Isoflavones in Humans
Authors: Cassidy Aedin
Published: February 2020

To fully evaluate the potential risks and benefits of isoflavones to human health, an understanding of the physiological behavior of these compounds following ingestion is required. Numerous researchers have investigated the kinetics and extent of polyphenol absorption by measuring plasma concentrations and/or urinary excretion among adults after the ingestion of a single dose of polyphenol, provided as either a pure compound, plant extract, or whole food/beverage. Available data suggest isoflavones are more bioavailable than other flavonoid subclasses. This review will focus on our current understanding of factors affecting isoflavone absorption and metabolism in humans.
Stability of Pesticides on Solid-Phase Extraction Disks After Incubation at Various Temperatures and for Various Time Intervals: Interlaboratory Study
Authors: Cobb Jean M , Mattice John D , Senseman Scott A , Dumas Jose A , Mersie Wondi , Riley Melissa B , Potter Thomas L , Mueller Thomas C , Watson Elizabeth B
Published: February 2020

An interlaboratory study was conducted at 8 locations to assess the stability of pesticides on solid-phase extraction (SPE) disks after incubation at various temperatures and for various time intervals. Deionized water fortified with selected pesticides was extracted by using 2 types of SPE filtration disks (Empore C18 and Speedisk® C18XF), and after extraction, the disks were incubated at 3 temperatures (25, 40, and 55C) and for 2 time intervals (4 and 14 days). Deionized water was fortified with atrazine, carbofuran, and chlorpyrifos by all participating laboratories. In addition, some of the laboratories included 2 of the following pesticides: metolachlor, metribuzin, simazine, chlorothalonil, and malathion. Concurrently, fortified water samples were extracted with the incubated samples by using each disk type at 4 and 14 days. Pesticides had equivalent or greater stability on ≤1 of the C18 disk types, compared with storage in water. The lowest recoveries of carbofuran (6%) and chlorpyrifos (7%) were obtained at 55C after storage for 14 days in incubated water. At 55C after 14 days, the lowest recovery for atrazine was 65% obtained by using Empore disks. Pesticide-specific losses occurred on the C18 disks in this study, underlining the importance of temperature and time interval when water is extracted at remote field locations and the SPE disks containing the extracted pesticides are transported or shipped to a laboratory for elution and analysis.
Determination of Monensin, Narasin, and Salinomycin in Mineral Premixes, Supplements, and Animal Feeds by Liquid Chromatography and Post-Column Derivatization: Collaborative Study
Authors: Campbell Harold , Nayeri Gita ,   Collaborators:, Costa J M , deJong J , Felgueiras I , Genouel C , Ivanova S , Krabel B , Lin H , Metra P L , Petrova J , Provost L , Riter K L , Sabbatini J , van der Kamp H
Published: February 2020

A liquid chromatographic (LC) method for the analysis of monensin, narasin, and salinomycin in mineral premixes, supplements, and complete animal feeds at medicating and trace levels was collaboratively studied. The method uses methanolwater (90 + 10) extraction with mechanical shaking for 1 h, filtration, and dilution if necessary. Determination of the 3 ionophores is by reversed-phase LC using post-column derivatization with vanillin and detection at 520 nm. Suspect positive trace-level products and medicated feeds containing unexpected ionophores are confirmed by hexane extraction or post-column derivatization with dimethylaminobenzaldehyde (DMAB). Twenty-five test samples of medicated feeds, supplements, and mineral and drug premixes, and 9 test samples for trace-level analysis were sent to 11 collaborators in Bulgaria, Czech Republic, Portugal, France, The Netherlands, United States, and Canada. Acceptable results were received from 10 laboratories. For the medicated complete feeds, supplements, and mineral premixes, RSDr values (within-laboratory repeatability) ranged from 2.5 to 5.2%, RSDR values (among-laboratory reproducibility) ranged from 2.7 to 6.8%, and HorRat values ranged from 0.31 to 1.30. For the drug premixes, the result variability was excessive and HorRat values ranged from 2.27 to 14.1. For the trace-level test samples, all laboratories correctly identified the analytes and did not report any false positives. RSDr values ranged from 1.3 to 9.5%, RSDR values ranged from 5.2 to 13.1%, and HorRat values ranged from 0.4 to 0.97.
First-Derivative Spectrophotometry in the Analysis of Rosiglitazone in Coated Tablets
Authors: Gomes Patricia , Steppe Martin
Published: February 2020

First-derivative spectrophotometry, applying the peak-zero method, was developed for the determination of rosiglitazone (RSG) in coated tablets. The solutions of standard and sample were prepared in ethanol. Quantitative determination of the drug was performed at 331.4 nm (N = 4; ▵λ= 3.2 nm) and was evaluated for the parameters specificity, linearity, precision, and accuracy. The specificity test showed that there was no interference from excipients commonly found in the commercial pharmaceutical formulation at 331.4 nm. The standard curve showed a correlation coefficient of 0.9997. Precision was demonstrated by a relative standard deviation value of 0.50%. The recovery test resulted in an average of 100.06%, which confirmed the accuracy of the method. The results for first-derivative spectrophotometry (D1), liquid chromatography, and micellar electrokinetic chromatography were compared by analysis of variance (ANOVA), and there were no significant differences among these methods. Therefore, D1 can be easily and directly applied to analyze RSG in coated tablets.
Development and In-house Validation of a Microbiological Assay for Determination of Cefepime in Injectable Preparations
Authors: Souza Marinês J , Kulmann Rosecler R , Silva LucÊlia M , Nogueira Daniele R , Zimmermann Estevan S , Schmidt Cleber A
Published: February 2020

Cefepime is a new parenteral cephalosporin that has been described as a fourth-generation, broad-spectrum antibiotic. This paper reports the development and in-house validation of an agar diffusion bioassay using a cylinder-plate method for the determination of cefepime in powder for injection. The validation performed yielded good results in terms of linearity, precision, accuracy, and robustness. The assay is based on the inhibitory effect of cefepime upon the strain of Micrococcus luteus ATCC 10240 used as the test microorganism. The results of assays were treated statistically by analysis of variance (ANOVA) and were found to be linear (r = 0.99993) in the selected range of 8.032.0 g/mL; precise [repeatability: relative standard deviation (RSD) = 1.39%, intermediate precision: between-day RSD = 1.77%, and between-analyst RSD = 1.97%] and accurate. Comparison of bioassay and liquid chromatography by ANOVA showed no significant difference between methodologies. The results demonstrated the validity of the proposed bioassay, which is a simple and useful alternative methodology for cefepime determination in routine quality control.
Microbiological Assay for the Determination of Telithromycin in Tablets
Authors: Vaucher Lauren C , Breier Ana R , Schapoval Elfrides E S
Published: February 2020

This study describes the development and validation of a microbiological assay, applying the cylinder-plate method, for the determination of the antibiotic telithromycin. The microbiological method consisted of a cylinder-plate agar diffusion assay using Micrococcus luteus ATCC 9341 as the test microorganism. The response graphs for standard and sample solutions were linear (r = 0.9987), and no parallelism deviations were detected in the tested concentrations (0.25, 0.5, and 1.0 g/mL). The interday precision was 2.67%. Recovery values were between 96.75 and 100.91%. A preliminary stability study of telithromycin showed that the microbiological assay is specific for the determination of telithromycin in the presence of its degradation products. The proposed method allows the quantitation of telithromycin in pharmaceutical dosage form and can be used for drug analysis in routine quality control.
Headspace Gas ChromatographyFlame Ionization Detector Method for Organic Solvent Residue Analysis in Dietary Supplements
Authors: Jeong Mijeong Lee , Zahn Michael , Trinh Thao , Jia Qi , Ma Wenwen
Published: February 2020

An analytical method has been developed for the identification and quantification of 20 organic solvent residues in dietary supplements. The method utilizes a headspace sampler interfaced with gas chromatography and flame ionization detection. With split injection (5:1) and a DB-624 column, most of the organic solvents are separated in 9 min. The method has been validated and was found to be relatively simple and fast, and it can be applied to most common organic solvent residues. With the mass detector, the method was able to identify organic solvents beyond the 20 standards tested.
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

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

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

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

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 >95%, coefficients of variation (precision) of <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

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

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 >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

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

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 < 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

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 <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

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

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

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

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

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

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.
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

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

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

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 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

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

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

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

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 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

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.