bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extraction of Aflatoxins B1 and G1 from Maize by Using Aqueous Sodium Dodecyl Sulfate
Authors: Maragos Chris M 
Published: February 2020

Abstract
Aflatoxins are potent carcinogens produced by certain Aspergillus fungi. The aflatoxins were first discovered in the 1960s, and since then have been found to be distributed worldwide in a variety of commodities, foods, and feeds. Many of the early techniques for detecting aflatoxins involved extraction with halogenated solvents. With the increased availability and use of reversed-phase solid-phase extraction cartridges and the availability of immunoaffinity columns, aqueous mixtures of nonhalogenated solvents have been frequently used. To further reduce the need for solvents, we examined the effects of eliminating solvents during the extraction of maize, using aqueous mixtures of the detergent sodium dodecyl sulfate. After extraction and filtration, aflatoxins B1 (AFB1)and G1 (AFG1) were isolated by using commercially available immunoaffinity columns. The isolated AFB1 and AFG1 were derivatized with trifluoroacetic acid before separation by liquid chromatography with fluorescence detection. In spiked maize, the limits of detection were 0.5 and 1 ng/g for AFB1 and AFG1, respectively. Recoveries of AFB1 from maize spiked at 120 ng/g averaged 87.5 (range, 76.399.0), with an average repeatability relative standard deviation (RSDr) of 4.0. Recoveries of AFG1 from maize spiked at 220 ng/g averaged 80.4 (range, 70.385.8), with an average RSDr of 3.5. This is the first reported demonstration of an effective solvent-free extraction of aflatoxins from maize at ambient pressure, and this extraction procedure may serve to help reduce solvent consumption during aflatoxin analysis.
Determination of Sulfur Amino Acids in Foods as Related to Bioavailability
Authors: Rutherfurd Shane M , Moughan Paul J 
Published: February 2020

Abstract
During the processing of feedstuffs and foods, methionine can be oxidized to methionine sulfoxide and methionine sulfone, and cysteine can be oxidized to cysteic acid. Methionine sulfone and cysteic acid are nutritionally unavailable, but methionine sulfoxide can be utilized, at least to some degree. The degree of utilization depends on the levels of methionine, cysteine, and methionine sulfoxide in the diet, but there is no consensus in the literature on the quantitative impact of these dietary constituents on methionine sulfoxide utilization. Methionine and cysteine are most often determined after quantitative oxidation to methionine sulfone and cysteic acid, respectively, using performic acid oxidation prior to hydrolysis. However, this method may overestimate the methionine content of processed foods, as it will include any methionine sulfoxide and methionine sulfone present. A selection of analytical methods has been developed to allow the separate determination of the 3 oxidized forms of methionine, the merits of which are discussed in this review. An additional consideration for determining methionine and cysteine bioavailability is that not all dietary methionine and cysteine is digested and absorbed from the small intestine. Selected methods designed to determine the extent of digestion and absorption are discussed. Finally, a concept for a new assay for determining methionine bioavailability, which includes determining the digestibility of methionine and methionine sulfoxide as well as the utilization of methionine sulfoxide, is presented.
High-Performance Thin-Layer Chromatography Densitometric Method for the Quantification of Harmine, Harmaline, Vasicine, and Vasicinone in Peganum harmala
Authors: Pulpati Harsha , Biradar Yogesh S , Rajani Mandapati 
Published: February 2020

Abstract
Peganum harmala Linn. seed is a reputed drug of the Indian systems of medicine. We report a simple high-performance thin-layer chromatography (HPTLC) densitometric method for the quantification of 4 alkaloids, viz., harmine, harmaline, vasicine, and vasicinone from P. harmala seed. The 4 compounds were resolved in ethyl acetatemethanolammonia (7 1 0.3, v/v/v) mobile phase. The method was validated for precision, repeatability, and accuracy. Instrumental precision was 0.27, 1.53, 0.39, and 1.15% [relative standard deviation (RSD)] and repeatability of the method was 1.01, 0.79, 0.13, and 1.62% RSD for harmine, harmaline, vasicine, and vasicinone, respectively. Accuracy of the method was checked by a recovery study conducted at 3 different levels, and the average recovery was 97.88% for harmine, 97.69% for harmaline, 98.38% for vasicine, and 98.28% for vasicinone. The 4 compounds were quantified in P. harmala seed using the method, and it was found to contain 0.44, 0.096, 0.25, and 0.0007% (w/w) of each, respectively. The proposed HPTLC densitometric method for the quantification of the 4 compounds was found to be simple, precise, specific, sensitive, and accurate. It can be used for routine quality control of P. harmala seed and has the ability to quantify the 4 marker compounds in the formulations containing P. harmala. It also can be used to quantify any of these marker compounds in other herbal drugs.
Polymeric Matrix Membrane Sensors for Stability-Indicating Potentiometric Determination of Oxybutynin Hydrochloride and Flavoxate Hydrochloride Urogenital System Drugs
Authors: Heba Mohamed , Ramadan Nesrin , El-Laithy Moustafa 
Published: February 2020

Abstract
Four polyvinyl chloride (PVC) matrix membrane electrodes responsive to 2 drugs affecting the urogenital systemoxybutynin hydrochloride (OX) and flavoxate hydrochloride (FX)were developed, described, and characterized. A precipitation-based technique with tungstophosphate (TP) and ammonium reineckate (R) anions as electroactive materials in a PVC matrix with an OX cation was used for electrode 1 and 2 fabrication, respectively. Electrode 3 and 4 fabrication was based on use of the precipitation technique of FX cation with tetrakis (4-chlorophenyl) borate and R anions as electroactive materials. Fast and stable Nernstian responses in the range 1 1021 106 M for the 2 drugs over the pH range 58 revealed the performance characteristics of these electrodes, which were evaluated according to International Union of Pure and Applied Chemistry recommendations. The method was applied to FX and OX in their pharmaceutical formulations and in human plasma samples. The 4 proposed sensors were found to be specific for the drugs in the presence of up to 60 of their degradation products. Validation of the method according to the quality assurance standards showed suitability of the proposed electrodes for use in the quality control assessment of these drugs. The recoveries for determination of the drugs by the 4 proposed selective electrodes were 99.5 0.5, 100.0 0.4, 99.9 0.4, and 100.1 0.4 for sensors 14, respectively. Statistical comparison between the results obtained by this method and the official method of the drugs was done, and no significant difference found.
Colorimetric Determination of Sildenafil Citrate (Viagra) Through Ion-Associate Complex Formation
Authors: Amin Alaa S , Moustafa Moustafa E , El-Dosoky Reham M S 
Published: February 2020

Abstract
A simple, quick, accurate, and sensitive colorimetric method is described for the determination of sildenafil citrate (SLD). The method is based on the reaction of SLD with Congo Red, Sudan II, and Gentian Violet in buffered aqueous solutions at pH 2.5, 6.5, and 11.0, respectively, to give highly colored soluble ion-associate complex species; the colored products are quantitated colorimetrically at 523, 554, and 569 nm, respectively. The various experimental conditions were optimized. The stoichiometric ratio was found to be 1:1 for all ion associates; the calculated logarithmic stability constants were 8.51, 7.79, and 5.58, respectively. Beer's law was obeyed over the concentration range of 0.27.0 g/mL, whereas the Ringbom optimum concentration range was 0.46.5 g/mL. Values for molar absorptivity, Sandell sensitivity, and detection and quantification limits were also calculated. The proposed method was successfully applied to the determination of SLD in Viagra tablets and in serum samples by using the technique of standard additions with mean accuracy values of 100.06 1.14, 99.87 0.70, and 99.86 0.97 for Viagra tablets and 99.88 0.60, 99.90 0.90, and 100.24 0.80 for serum samples, respectively.
Utilization of Picolinaldehyde-4-phenyl-3-thiosemicarbazone in Sodium Dodecylsulfate Micelles for the Spectrophotometric Determination of Iron, Vanadium, and Cobalt Following Partial Least-Squares Regression Analysis
Authors: Balouch Aamna , Memon Najma , Bhanger Muhammad I , Khuhawar Muhammad Y 
Published: February 2020

Abstract
Partial least-squares regression was applied for the simultaneous determination of iron, vanadium, and cobalt after complexation with picolinaldehyde-4-phenyl-3-thiosemicarbazone (PAPT) in the presence of anionic sodium dodecylsulfate (SDS) micelles. These 3 complexed metal ions exhibited overlapping spectra in the 390510 nm region with a maximum absorbance at 415 nm at pH 3.0 and enhanced absorbance in the presence of SDS. The data for the simultaneous determination of these metal ions were analyzed using a simple partial least-squares (SIMPLS) algorithm. Formation constants (log Kf) were found to be 4.65, 3.29, and 4.85 for PAPT complexes of Fe, V, and Co, respectively, and the detection limits for Fe, V, and Co were 0.013, 0.002, and 0.010 g/mL, respectively. Common anions and cations did not interfere with the proposed method. The method was validated by calculating root mean square error of cross-validation, root mean square error of calibration, and root mean square error of prediction and was applied to determine these 3 metal ions in real crude oil samples.
Variability Among Four Laboratories of the Filter Bag Technique to Determine Acid and Neutral Detergent Fiber Contents in Ruminant Feeds from Argentina
Authors: Fay José P , Guaita María S , Danelón José L , Chifflet Sonia , Wawrzckiewicz Marisa , Díaz Carolina , Ross Deborah A , Fernndez Héctor M 
Published: February 2020

Abstract
The objective of this work was to evaluate the filter bag technique (FBT) in an ANKOM 200 fiber analyzer to assess its accuracy for the determination of acid and neutral detergent fiber (ADF and NDF, respectively) contents in common ruminant feeds from the temperate region of Argentina. The evaluation was done in a ring test of 4 laboratories. The 3 Argentine laboratories were from the College of Agronomy, University of Buenos Aires, the College of Agricultural Sciences of the Catholic University of Argentina, and the Balcarce Agricultural Experiment Station of the National Institute of Agricultural Technology (INTA). The fourth laboratory was from the Department of Animal Science of Cornell University, Ithaca, NY. The feeds utilized were soybean meal expeller, whole sunflower seed, corn grain, herbages of alfalfa, ryegrass, tall wheatgrass, weeping lovegrass, guinea and barley grasses, and silages of corn and of a natural grassland. Results indicated that values obtained in the 4 laboratories were consistent regardless of the laboratory where the analyses were performed. It was concluded that the FBT in the ANKOM instrument gave satisfactory results when used for the determination of both ADF and NDF across samples having a wide range of fiber contents, and that the among-laboratories variability of this methodology was low.
Validation of a Modification to Performance-Tested MethodSM 010403: Microwell DNA Hybridization Assay for Detection of Listeria spp. in Selected Foods and Selected Environmental Surfaces
Authors: Alles Susan , Peng Linda X , Mozola Mark A 
Published: February 2020

Abstract
A modification to Performance-Tested MethodSM 010403, GeneQuence&lt;sup/&gt; Listeria Test (DNAH method), is described. The modified method uses a new media formulation, LESS enrichment broth, in single-step enrichment protocols for both foods and environmental sponge and swab samples. Food samples are enriched for 2730 h at 30C, and environmental samples for 2448 h at 30C. Implementation of these abbreviated enrichment procedures allows test results to be obtained on a next-day basis. In testing of 14 food types in internal comparative studies with inoculated samples, there were statistically significant differences in method performance between the DNAH method and reference culture procedures for only 2 foods (pasteurized crab meat and lettuce) at the 27 h enrichment time point and for only a single food (pasteurized crab meat) in one trial at the 30 h enrichment time point. Independent laboratory testing with 3 foods showed statistical equivalence between the methods for all foods, and results support the findings of the internal trials. Overall, considering both internal and independent laboratory trials, sensitivity of the DNAH method relative to the reference culture procedures was 90.5. Results of testing 5 environmental surfaces inoculated with various strains of Listeria spp. showed that the DNAH method was more productive than the reference U.S. Department of Agriculture-Food Safety and Inspection Service (USDA-FSIS) culture procedure for 3 surfaces (stainless steel, plastic, and cast iron), whereas results were statistically equivalent to the reference method for the other 2 surfaces (ceramic tile and sealed concrete). An independent laboratory trial with ceramic tile inoculated with L. monocytogenes confirmed the effectiveness of the DNAH method at the 24 h time point. Overall, sensitivity of the DNAH method at 24 h relative to that of the USDA-FSIS method was 152. The DNAH method exhibited extremely high specificity, with only 1 false-positive reactions overall.
Application of Graphitized Carbon Black to the QuEChERS Method for Pesticide Multiresidue Analysis in Spinach
Authors: Li Li , Li Wei , Qin Dongmei , Jiang Shuren , Liu Fengmao 
Published: February 2020

Abstract
A modified QuEChERS method was optimized to determine 66 pesticide residues in spinach using gas chromatography with mass spectrometric detection in selected-ion monitoring mode. Graphitized carbon black (GCB) at different levels (0, 5, 10, 15, 20, and 25 mg) was used to adsorb the pigments in spinach extracts. Best recoveries with less colored extract samples for all pesticides analyzed were obtained in the presence of 10 mg GCB. Under the optimized condition, analyses of spiked samples were performed at 3 different levels. Correlation coefficients, R2, in the linear range tests were better than 0.99. Average recoveries ranged from 66 to 104, with the relative standard deviation below 16. The limits of quantitation ranged from 50 to 250 g/kg.
Determination of Ultratrace Amounts of Ce3 in the Presence of Sm3, La3, Dy3, and Yb3 in Water and Soils by Inductively Coupled Plasma-Optical Emission Spectroscopy After Preconcentration with Thio-Functionalized MCM-41 at Controlled
pH
Authors: Saberyan Kamal 
Published: February 2020

Abstract
A method is presented for the selective preconcentration and determination of ultratrace amounts of Ce3 ions by inductively coupled plasma-optical emission spectroscopy in the presence of Sm3, La3, Dy3, Yb3, and common interfering ions. In this method, thio-functionalized MCM-41 is used in the preconcentration step. Extraction efficiency and the influence of sample matrix, pH of sample solution, type and minimum amount of tripping acid, and flow rates were investigated. The preconcentration is pH-dependent, and the best results were obtained in the pH range of 8.510.3. The maximum capacity of 2 mg absorbent was found to be 170 4 g. The detection limit of the measurements after the preconcentration step was found to be 114 ng Ce3/L.
Development and Validation of an LC Method for Simultaneous Determination of Amiloride Hydrochloride and Hydrochlorothiazide in Human Urine
Authors: Elshanawane Abdalla A , Mostafa Samia M , Elgawish Mohamed S 
Published: February 2020

Abstract
An HPLC method with photometric detection has been developed for determination of a binary mixture of amiloride hydrochloride and hydrochlorothiazide in human urine using chlorthalidone as the internal standard. Reversed-phase chromatography was performed at room temperature on a cyanopropyl column with the mobile phase consisting of a 10 mM KH2PO4 solution (pH 4.5)methanol (70 + 30, v/v) at a flow rate of 1 mL/min. The detector was set at 214 nm. The total analysis time was 10 min. The method was validated in terms of accuracy, precision, absolute recovery, freeze-thaw stability, bench-top stability, and re-injection reproducibility. The procedure shows good accuracy, repeatability, and selectivity. Moreover, the method was applied directly to urine that had not undergone prior treatment. The intra- and interday coefficients of variation for all compounds were below 4, and the method was highly accurate, with a relative error for all compounds that was below 8. No interference from endogenous compounds in urine samples was found. The proposed method, which is rapid, simple, and does not require any separation steps, has been successfully applied to the assay of human urine containing amiloride hydrochloride and hydrochlorothiazide.
Analysis Method Study on 839 Pesticide and Chemical Contaminant Multiresidues in Animal Muscles by Gel Permeation Chromatography Cleanup, GC/MS, and LC/MS/MS
Authors: Pang Guo-Fang , Cao Yan-Zhong , Fan Chun-Lin , Jia Guang-Qun , Zhang Jin-Jie , Li Xue-Min , Liu Yong-Ming , Shi Yu-Qiu , Li Zeng-Yin , Zheng Feng , Lian Yu-Jing 
Published: February 2020

Abstract
The paper reports the study of gel permeation chromatography (GPC), gas chromatography/mass spectrometry (GS/MS), and column chromatography tandem MS (LC/MS/MS) for 839 pesticides and chemical contaminants, through which a GPC data bank has been established for 744 pesticides, a GC/MS data bank for 541 pesticides, and an LC/MS/MS data bank for 464 pesticides. On the basis of this study, a new method for quantitative determination of 587 pesticide residues in animal muscles such as beef, mutton, pork, chicken, and rabbit has been established using GPC cleanup followed by GC/MS and LC/MS/MS. In the method, 10 g animal samples were mixed with 20 g sodium sulfate and extracted twice with 35 mL cyclohexaneethyl acetate (1 + 1) by blender homogenization followed by centrifugation, filtration, and concentration. An equivalent of 5 g sample was injected into a 400 25 mm S-X3 GPC column, with cyclohexaneethyl acetate (1 + 1) as the mobile phase at a flow rate of 5 mL/min. The 2240 min fraction was collected for subsequent analysis. For the 478 pesticides determined by GC/MS, the portions collected from GPC were concentrated to 0.5 mL and exchanged twice with 5 mL hexane. For the 379 pesticides determined by LC/MS/MS, the portions collected from GPC were dissolved with acetonitrilewater (60 + 40) after taking the extract to dryness with nitrogen gas. At the limit of quantification (LOQ) and 10 LOQ fortification levels of 0.116 000 g/kg, recoveries were within 40130, among which 563 pesticide recoveries were between 60 and 130, accounting for 96 of the compounds; 24 analytes were recovered between 40 and 60, accounting for 4 of the compounds. The relative standard deviation was below 30 for all 587 pesticides. The limits of detection for the method were 0.11600 g/kg. In comparison with GC/MS, LC/MS/MS increased the detection sensitivity 21000 times for 236 pesticides.
Simultaneous Enrichment-Separation of Metal Ions from Environmental Samples by Solid-Phase Extraction Using Double-Walled Carbon Nanotubes
Authors: Soylak Mustafa , Unsal Yunus Emre 
Published: February 2020

Abstract
A solid-phase extraction (SPE) method has been developed using a column filled with double-walled carbon nanotubes for the preconcentrationseparation of Co(II), Cu(II), Ni(II), Pb(II), Fe(III), and Mn(II) ions. Experimental parameters, including pH of the solution, sample volume, flow rate of the sample solution and eluents, etc., were investigated. Quantitative recoveries for the anayte ions were obtained at pH 9.0 with 2 M HNO3 eluent at a flow rate of 2 mL/min. The influences of matrix ions were also investigated. The preconcentration factor was 100. Addition and recovery experiments for analyte ions in real water samples gave good results. The validity of the presented SPE method was tested by analysis of HR-1 Humber River Sediment certified reference material for each element.
Simultaneous Determination of Residual Thiamphenicol and Florfenicol in Foods of Animal Origin by HPLC/Electrospray Ionization-MS/MS
Authors: Chou Kuang Yu , Cheng Tsung Yao , Chen Ching Mei , Hung Pei Ling , Tang Yu Yun , Chung-Wang Yueh Jong , Shih Yang-Chih 
Published: February 2020

Abstract
A simple and reliable method using HPLC/MS/MS has been developed for determination of thiamphenicol and florfenicol in foods of animal origin, such as pork, porcine liver, porcine kidney, beef, bovine liver, fish, and chicken. The HPLC separation was performed on a Waters XTerra phenyl column (100 2.1 mm, 3.5 m) with a gradient mobile phase system of 0.1 formic acidmethanol at a flow rate 0.35 mL/min. Negative ionization produced the molecular ions at m/z 354 and 356 for thiamphenicol and florfenicol, respectively. Two characteristic transition reactions (m/z 354185, 290 and m/z 356336, 185) in the selected reaction monitoring mode were tested for detection and confirmation of thiamphenicol and florfenicol simultaneously. The analytes were extracted with ethyl acetate and defatted with n-hexane by liquidliquid extraction. The recoveries of thiamphenicol and florfenicol by the developed method were 72.597.6. The limits of determination were 1.0 ng/g (ppb) for both compounds.
New Nonextractive and Highly Sensitive High-Performance Liquid Chromatographic Method for Determination of Paroxetine in Plasma After Offline Precolumn Derivatization with 7-Chloro-4-Nitrobenzo-2-Oxa-1,3-Diazole
Authors: Darwish Ibrahim A , Al-Majed Abdulrahman A , Mahmoud Ashraf M , Khalil Nasr Y 
Published: February 2020

Abstract
New nonextractive and simple offline precolumn derivatization procedures have been proposed, for the first time, for the trace determination of paroxetine (PXT) in human plasma by HPLC with fluorescence detection. Trimetazidine (TMZ) was used as an internal standard. Plasma samples were treated with acetonitrile for protein precipitation and then derivatized with 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole in borate buffer of pH 8 at 70C for 30 min. Separations of the derivatized PXT and TMZ were performed on a Nucleosil CN column using a mobile phase consisting of acetonitrile10 mM sodium acetate buffer (pH 3.5)methanol (47 + 47 + 6, v/v) at a flow rate of 1.0 mL/min. The derivatized samples were excited at 470 nm and monitored at an emission wavelength of 530 nm. Under the optimum chromatographic conditions, a linear relationship with good correlation coefficient (r 0.9998, n 7) was found between the peak area ratio and PXT concentrations in the range of 5600 ng/mL. The LOD and LOQ were 1.37 and 4.14 ng/mL, respectively. The intraday and interassay precisions were satisfactory; the RSD did not exceed 4.2. The accuracy of the method was proved by recovery of PXT from spiked human plasma at levels of 97.28104.38 0.413.62. The proposed method had high throughput, as the analysis involved a simple sample pretreatment procedure and short run time (&lt;10 min). The results demonstrated that the method would have a great value when it is applied in the therapeutic monitoring of PXT.