bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chromatographic Determination of Amino Acids in Foods
Authors: Peace Robert W , Gilani G Sarwar 
Published: February 2020

Abstract
Amino acids in foods exist in a free form or bound in peptides, proteins, or nonpeptide bonded polymers. Naturally occurring L-amino acids are required for protein synthesis and are precursors for essential molecules, such as co-enzymes and nucleic acids. Nonprotein amino acids may also occur in animal tissues as metabolic intermediates or have other important functions. The development of bacterially derived food proteins, genetically modified foods, and new methods of food processing; the production of amino acids for food fortification; and the introduction of new plant food sources have meant that protein amino acids and amino acid enantiomers in foods can have both nutritional and safety implications for humans. There is, therefore, a need for the rapid and accurate determination of amino acids in foods. Determination of the total amino acid content of foods requires protein hydrolysis by various means that must take into account variations in stability of individual amino acids and resistance of different peptide bonds to the hydrolysis procedures. Modern methods for separation and quantitation of free amino acids either before or after protein hydrolysis include ion exchange chromatography, high performance liquid chromatography (LC), gas chromatography, and capillary electrophoresis. Chemical derivatization of amino acids may be required to change them into forms amenable to separation by the various chromatographic methods or to create derivatives with properties, such as fluorescence, that improve their detection. Official methods for hydrolysis and analysis of amino acids in foods for nutritional purposes have been established. LC is currently the most widely used analytical technique, although there is a need for collaborative testing of methods available. Newer developments in chromatographic methodology and detector technology have reduced sample and reagent requirements and improved identification, resolution, and sensitivity of amino acid analyses of food samples.
The Protein Digestibility-Corrected Amino Acid Score (PDCAAS)—A Concept for Describing Protein Quality in Foods and Food Ingredients: A Critical Review
Authors: Schaafsma Gertjan 
Published: February 2020

Abstract
Protein Digestibility-Corrected Amino Score (PDCAAS) is discussed. PDCAAS is now widely used as a routine assay for protein quality evaluation, replacing the more traditional biological methods [e.g., measurement of the Protein Efficiency Ratio (PER) in rats]. PDCAAS is based on comparison of the essential amino acid content of a test protein with that of a reference essential amino acid pattern and a correction for differences in protein digestibility as determined using a rat assay. Although PDCAAS is a rapid and useful method, it often shows discrepancies when compared to PER values. These discrepancies relate to the following issues: uncertainty about the validity of reference patterns, invalidity of correction for fecal (versus ileal) digestibility, truncation of PDCAAS values to 100%, failure to obtain full biological response after supplementation of the limiting essential amino acid, discrepancies between protein and amino acid digestibility, effects of processing on protein quality, and effects of the presence of antinutritional factors in the matrix containing the protein. Part of the discrepancy between PDCAAS and PER can be overcome by modifications of PDCAAS. This article describes some proposed modifications and puts forward the suggestion that the rat protein fecal digestibility assay be replaced by an in vitro ileal amino acid digestibility assay based on a computer-controlled gastrointestinal model.
Biological Assay and Liquid Chromatographic Method for Analysis of Moxifloxacin in Tablets
Authors: Guerra Fanny L B , Paim Clesio S , Steppe Martin , Schapoval Elfrides E S 
Published: February 2020

Abstract
A microbiological assay and a liquid chromatographic method were validated for quantitation of moxifloxacin in tablets. The microbiological method consisted of a cylinder-plate agar diffusion assay using Micrococcus luteus ATCC 9341 as the test microorganism and phosphate buffer (0.1M, pH 8.0) as the diluent solution. The response graphs for standard and sample solutions were linear (r = 0.9479), and no parallelism deviations were detected in the tested levels of concentration (4.0, 8.0, and 16.0 μg/mL). The interday precision was 2.73%. Recovery values were between 96.25 and 100.5%. The chromatographic analyses were performed using a Shim-pack CLC-ODS column (250 × 4.6 mm, 5 μm) with a mobile phase consisting of (A) a mixture of phosphoric acid (0.17%, v/v) with tetramethylammonium hydroxide (0.05M) and acetonitrile (95 + 5, v/v) and (B) methanol (55 + 45, v/v) adjusted to pH 3.0. The flow rate was 1.0 mL/min, and detection was made at 294 nm. The method was linear in a range from 12.0 to 42 μg/mL (r = 0.9999), and the interday precision was 1.39%. Recovery ranged between 101.9 and 103. 81%. Both validated methods were used to quantify the moxifloxacin content in tablets exposed to ultraviolet radiation, and similar results were obtained.
Kinetics of Thermal Decomposition of 4-Carboxyl-2,6-Dinitrobenzenediazonium Ion (CDNBD)
Authors: Idowu Olakunle S , Kolawole Abiola O , Adegoke Olajire A , Kolade Yetunde T , Fasanmade Adedigbo A , Olaniyi Ajibola A 
Published: February 2020

Abstract
The kinetics of thermal decomposition of 4-carboxyl-2,6-dinitrobenzenediazonium ion (CDNBD), an arenediazonium ion newly developed as a derivatizing reagent for drug analysis, are described. The arenediazonium ion, in an optimized concentrated sulfuric acid/orthophosphoric acid medium, was incubated for various time intervals at 30°, 45°, 55°, 65°, 75°, and 85°C. The amount of ion left after each time interval was quantified selectively by colorimetric assay at 490 nm, using mefenamic acid as a model diazo-coupling component. The rate constants for the decomposition were determined graphically. An Arrhenius plot was used to delineate the dependence of the rate constant on temperature and to predict the half-life at 25°C and lower temperatures. The diazonium ion decomposed by first-order kinetics. The rate constants of decomposition, which increased progressively with temperature, were 3.18 ± 0.41 × 10−5, 1.19 ± 0.07 × 10−4, 4.87 ± 0.15 × 10−4, 12.88 ± 0.73 × 10−4, and 21.32 ± 2.74 × 10−4 (s−1) with corresponding half-lives of 363, 97.06, 23.72, 8.97, and 5.42 min at 30°, 45°, 55°, 65°, and 75°C, respectively. CDNBD is highly stable in concentrated acid medium, with half-life values of about 10 h, 10 days, and 7.3 months at 25°, 0°, and −20°C, respectively. The reagent stability profile shows that it could be readily adapted for routine applications in instrumental chemical analysis.
Simultaneous Determination of Caffeine, 8-Chlorotheophylline, and Chlorphenoxamine Hydrochloride in Ternary Mixtures by Ratio-Spectra Zero-Crossing First-Derivative Spectrophotometric and Chemometric Methods
Authors: Kelani Khadiga M 
Published: February 2020

Abstract
A ratio-spectra zero-crossing first-derivative spectrophotometric method and 2 chemometric methods have been used for the simultaneous determination of ternary mixtures of caffeine (A), 8-chlorotheophylline (B), and chlorphenoxamine hydrochloride (C) in bulk powder and dosage forms. In the ratio-spectra zero-crossing first-derivative spectrophotometric technique (1DD), calibration curves were linear in the range of 4–20 μg/mL for A, B, and C (r = 0.9992, 0.9994, and 0.9976, respectively). The measurements were carried out at 212, 209.2, and 231.4 nm for A, B, and C, respectively. The detection limits for A, B, and C were calculated to be 0.24, 0.34, and 0.13 μg/mL, and the percentage recoveries were 99.1 ± 0.89, 100.1 ± 0.95, and 100.1 ± 1.0, respectively. Two chemometric methods, namely, the partial least-squares (PLS) model and the principal component regression (PCR) model, were also used for the simultaneous determination of the 3 drugs in the ternary mixture. A training set consisting of 15 mixtures containing different ratios of A, B, and C was used. The concentration used for the construction of the PLS and PCR models varied between 4 and 25 μg/mL for each drug. These models were used after their validation for the prediction of the concentrations of A, B, and C in mixtures. The detection limits for A, B, and C were calculated to be 0.13, 0.15, and 0.14 μg/mL, respectively, and the percent recoveries were found to be 99.8 ± 0.96, 99.9 ± 0.94, and 99.9 ± 1.18, respectively, for both methods. The 3 proposed procedures are rapid, simple, sensitive, and accurate. No preliminary separation steps or resolution equations are required; thus, they can be applied to the simultaneous determination of the 3 drugs in commercial tablets and suppositories or in quality-control laboratories.
Voltammetric Behavior of Zaleplon and Its Differential Pulse Polarographic Determination in Capsules
Authors: Larenas Gipsy , Bollo Soledad , Rodriguez Marcelo , Lemus Igor , Nuñez-Vergara Luis J , Squella Juan A , Álvarez-Lueje Alejandro 
Published: February 2020

Abstract
In this work both the electrochemical behavior and the analysis of the hypnotic pyrazolopyrimidine derivative zaleplon were studied. Zaleplon in ethanol–0.1M Britton Robinson buffer solution (30–70) showed 2 irreversible, well-defined cathodic responses in the pH range of 2–12 using differential pulse polarography (DPP), tast polarography, and cyclic voltammetry. From chronocoulometric studies, it was possible to conclude that one electron was transferred in each reduction peak or wave. For analytical purposes, the DPP technique working at pH 4.5 for peak I was selected, which exhibited adequate repeatability, reproducibility, and selectivity. The recovery was 99.97 ± 1.52%, and the detection and quantitation limits were 5.13 × 10−7M and 1.11 × 10−6M, respectively. The DPP method was applied successfully to the individual assay of capsules in order to verify the content uniformity of zaleplon. Treatment of the sample is not required because the excipients do not interfere, the method is not time consuming, and it is less expensive than column liquid chromatography.
Quantitative Determination of Usnic Acid in Usnea lichen and Its Products by Reversed-Phase Liquid Chromatography with Photodiode Array Detector
Authors: Ji Xiuhong , Khan Ikhlas A 
Published: February 2020

Abstract
Usnic acid, a lichen substance, has a wide range of pharmaceutical applications, including antibiotic, antimycotic, antifeedant, antitubercular, antitumor, and analgesic activities. Some products containing usnic acid are marketed as weight control supplements; however, hepatotoxicity and acute liver failures were reported as severe side effects. The usnic acid content present in the plant materials and market products was analyzed by reversed-phase high-pressure liquid chromatography with a photodiode array detector at 233 nm. A Waters XTerra RP18 (150 × 4.6 mm; 5 μm particle size) column was the stationary phase; mobile phase was aqueous 0.1% acetic acid and acetonitrile gradient at flow rate of 1.0 mL/min. The temperature was held constant at 30°C. The retention time of usnic acid was approximately 13.3 min. Acetone extraction of the samples took place with sonication. The precision of the method was confirmed by a standard deviation below 3.0% (n = 3) and usnic acid recovery was 99.0%. Limit of detection was 0.4 μg/mL and the response was linear from 1.4 to 570.0 μg/mL with a correlation coefficient (R2) of 0.9991. The content of usnic acid in 4 raw materials and 22 finished products was analyzed.
Real-Time Polymerase Chain Reaction Approach for Quantitation of Ruminant-Specific DNA to Indicate a Correlation Between DNA Amount and Meat and Bone Meal Heat Treatments
Authors: Chiappini Barbara , Brambilla Gianfranco , Agrimi Umberto , Vaccari Gabriele , Aarts Henk J M , Berben Gilbert , Frezza Domenico , Giambra Vincenzo 
Published: February 2020

Abstract
The use of ruminant-derived proteins in ruminant feeds has been banned in both the European Union and the United States to prevent further spread of bovine spongiform encephalopathy. Enforcement of these regulations relies on the ability to identify the presence of prohibited proteins in feed. We developed a quantitative real-time polymerase chain reaction assay for the quantification of ruminant-specific DNA as index of protein content. The assay is based on the amplification of a 117 base pair mitochondrial 16S rRNA DNA gene fragment and an internal positive control (IPC). The use of an IPC permits compensation for differences in DNA extraction efficiency and avoids the occurrence of false-negative results. We demonstrated a decrease in target DNA amount with a difference of 2 logs between meat and bone meal (MBM) treated at 133° and 145°C. Such a difference indicates that bias could occur when DNA-based methods are used for quantitation purposes. Risk management could benefit from future efforts concerning validation of the method for MBM detection in feedstuff and safety evaluation of the use of animal-derived proteins in animal nutrition.
Analytical Method for Dimethenamid-P in Selected Raw Agricultural Commodities by Gas Chromatography with Electron Capture Detection
Authors: Anderson Kim A , Basile Jennifer L , Johnson Eugene R 
Published: February 2020

Abstract
A sensitive and simple method for the extraction and quantification of the herbicide dimethenamid-P from several raw agricultural commodities (RAC) is presented. The method provides sensitive and well-defined chromatography with baseline resolution in all matrixes tested. Homogenized samples were extracted with methanol–water, filtered, and then extracted with hexanes. A Florisil solid-phase extraction was then applied for the final cleanup. Sample separation and quantification were performed by gas chromatography with an electron capture detector. The instrument detection limit was 0.007 μg/mL, and the practical quantification limit was 0.003 μg/g (w/w) based on a 25 g sample. Recoveries for a series of fortified plant tissues ranged from 69 to 103%. The study demonstrated selective and sensitive recovery of dimethenamid-P from the RAC tested.
Authentication of Valeriana procera Kunth and Comparative Account of Five Valeriana Species
Authors: Joshi Vaishali C , Navarrete Andres , Khan Ikhlas A 
Published: February 2020

Abstract
Valeriana procera Kunth (Mexican Valerian) is a commercially important species, sometimes used as a substitute for Valeriana officinalis L., an important sedative in herbal medicine. A detailed macroscopic and microscopic account was provided for V. procera Kunth and a comparison was made between the wild and cultivated samples of V. procera Kunth. Macroand microscopic comparative analyses were performed to differentiate V. procera Kunth from V. officinalis L. and other commercially important Valerian species such as V. jatamansi Jones, Valeriana edulis Nutt, and V. sitchensis Bong.
Stability Study of Simvastatin under Hydrolytic Conditions Assessed by Liquid Chromatography
Authors: Álvarez-Lueje Alejandro , Valenzuela Christian , Squella Juan Arturo , Núñez-Vergara Luis Joaquín 
Published: February 2020

Abstract
In this work, a liquid chromatography stability-indicating method was developed and applied to study the hydrolytic behavior of simvastatin in different pH values and temperatures. The selected chromatographic conditions were a C18 column; acetonitrile–28 mM phosphate buffer solution, pH 4 (65 + 35) as the mobile phase; 251°C column temperature; and flow rate 1 mL/min. The developed method exhibited an adequate repeatability and reproducibility (coefficient of variation 0.54 and 0.74%, respectively) and a recovery higher than 98%. Furthermore, the detection and quantification limits were 9.1 × 10−7 and 2.8 × 10−6 M, respectively. The degradation of simvastatin fitted to pseudo-first order kinetics. The degradation was pH dependent, being much higher at alkaline pH than at acid pH. Activation energy, kinetic rate constants (k) at different temperatures, the half life (t1/2) and the time for 10% degradation to occur (t90) values are also reported.
Development and Validation of Routine Analysis Methods for the Determination of Essential, Nonessential, and Toxic Minor and Trace Elements in Cereal and Cereal Flour Samples by Inductively Coupled Plasma–Atomic Emission Spectrometry
Authors: Momen Awad A , Zachariadis George A , Anthemidis Aristidis N , Stratis John A 
Published: February 2020

Abstract
Various digestion procedures were carefully investigated and accurately evaluated with respect to their effect on the analysis of cereals and cereal flours. Multielement methods were selected and well developed for the determination of essential (Cr, Cu, Fe, Mg, Mn, and Zn), nonessential (Ag, Al, Ba, Bi, In, and Ga), and toxic (Cd and Pb) minor and trace elements by inductively coupled plasma–atomic emission spectrometry. Only Ag could be determined, either with aqueous standard or standard addition calibration methods, while the standard addition methods were more accurate for the determination of other elements. The recoveries were mostly within the range of 84.1–113% for the expected values of all analytes with respect to certified reference material NIST SRM 1586a (rice flour). The results proved that, for cereals and cereal flours, the use of H2O2 for wet digestion and HNO3 for dry ashing were not necessary. Linear regression analysis and Student's paired t-test were applied to evaluate the significant differences between different procedures and type of samples.
Youden Analysis of Karl Fischer Titration Data from an Interlaboratory Study Determining Water in Animal Feed, Grain, and Forage
Authors: Jones Frank E 
Published: February 2020

Abstract
Data from a recent interlaboratory study of the determination of water (moisture) in animal feed, grain, and forage (plant tissue) by Karl Fischer titration were re-analyzed using Youden plots. The purpose was to show the unique ability these plots possess of separating random and systematic errors visually while providing numerical estimates of the precision and the systematic error of the method. Furthermore, the usefulness of the technique is underscored because AOAC INTERNATIONAL allows the use of matched pairs in collaborative studies to obtain estimates of repeatability and reproducibility.
Comparison of the Compact Dry CF with the Most Probable Number Method (AOAC Official Method 966.24) for Enumeration of Coliform Bacteria in Raw Meats: Performance-Tested MethodSM 110401
Authors: Kodaka Hidemasa , Teramura Hajime , Nirazuka Tadanobu , Mizuochi Shingo , Goins David , Odumeru Joseph , Kokubo Yataro 
Published: February 2020

Abstract
Compact Dry CF is a ready-to-use test method for the enumeration of coliform bacteria in food. The plates are presterilized and contain culture medium and a cold water-soluble gelling agent. The medium should be rehydrated with 1 mL diluted sample inoculated into the center of the self-diffusible medium, allowing the solution to diffuse by capillary action. The plate can be incubated at 35C for 2024 h and the colonies counted without any further working steps. The Compact Dry CF medium plates were validated with 5 different raw meats. The performance tests were conducted at 35C. In all studies performed, no apparent differences were observed between the Compact Dry CF method and the AOAC Official Method 966.24 results. For the accuracy claim (n = 75), a correlation factor of r2 = 0.91 (coliform) could be assigned, as stated in the application for Performance-Tested MethodSM. No significant variations in coliform bacterial counts were observed with different production lots or plates of diverse storage age by the quality consistency and storage robustness studies.
Determination of Patulin in Apple Juice by Liquid Chromatography
Authors: Iha Maria Helena , Sabino Myrna 
Published: February 2020

Abstract
A method was developed and validated in-house for the determination of patulin (PAT), a toxic mold metabolite, in apple juice. The sample was extracted with ethyl acetatehexane and analyzed by liquid chromatography equipped with a C18 column and diode array detector. The mobile phase used for the quantification was waterethanol, at a flow rate of 0.5 mL/min. The method showed a mean recovery of 84.8%, the relative standard deviation obtained in the precision study was &lt;7.7%, the quantification and detection limits were 7 and 3 μg/L, respectively, and the linear range for PAT in apple juice was 2.6650 μg/L. The ruggedness was evaluated by an intralaboratory experiment, in which 5 factors were studied, and only one was found to influence the observed results. The developed method is fast, practical, and simple; the solvents (except hexane) and reagents used were nontoxic. The results of the validation confirmed the efficiency of the method, which is sensitive enough to be used in studies required to quantify PAT in apple juice.
Evaluation of the Sanita-kun Coliforms, a Dehydrated Medium Sheet for Coliform Detection: Performance-Tested MethodSM 100402
Authors: Morita Hiroshi , Ushiyama Masashi , Aoyama Shigeyuki , Iwasaki Mihoko , Andrews Wallace H , Betts Roy , Brodsky Michael H 
Published: February 2020

Abstract
The Sanita-kun Coliforms consists of a transparent cover film, an adhesive sheet, a layer of nonwoven fabric, and a water-soluble compound film, including a culture medium formula for the detection of coliforms. The medium sheet was validated with 26 food types belonging to 9 food categories (meat, poultry, fish and seafood, fruits and vegetable, dairy, chocolate or bakery, animal feeds, pasta, and miscellaneous) using violet red bile (VRB) agar method in the U.S. Food and Drug Administration's Bacteriological Analytical Manual as a reference according to the AOAC guideline. The medium sheet showed 100 inclusivity and exclusivity. Ruggedness study suggested allowances in the incubation temperature and time as 3335 and 24 4 h, respectively. The performance of 3 different lots of the medium sheets was equivalent and suggested no change of the performance at least for 3 years. In the comparative recovery study, many samples (84.6), which were inoculated with a coliform strain, showed no significant difference between the 2 methods. The linear correlation coefficient (r2) to the VRB agar was calculated as 0.94. In the repeatability study, the average relative standard deviation of total foods was 0.10 in the medium sheet. In the independent study, the medium sheet detected significantly more colonies than VRB plates in the frozen raw milk sample, while there was no significant difference between the 2 methods in raw ground beef sample. Comparative recovery study on foods, inoculated and then frozen, showed the medium sheet detected injured cells with better recovery than VRB agar. The analysts in the independent study wrote that the medium sheet was easy to use and read overall. The Sanita-kun sheet provides an alternative method to coliform count agar.