bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of 1,4-Dioxane in Household Detergents and Cleaners
Authors: Tanabe Akiko , Kawata Kuniaki 
Published: February 2020

Abstract
A possible human carcinogen, 1,4-dioxane, was investigated as to its concentration levels in household detergents and cleaners currently sold in Japan. A solid-phase extraction combined with stable isotope dilution and gas chromatographic/ mass spectrometric determination was evaluated for the determination of 1,4-dioxane in household products. The evaluation of the method was performed using a recovery study of 1,4-dioxane-d8 from detergent and cleaner samples. The mean overall recovery and relative standard deviation were 78 and 15, respectively. The limit of quantitation was 0.05 mg/kg. This method was satisfactorily applied to the determination of 1,4-dioxane in household products. 1,4-Dioxane was detected in 40 out of the 51 investigated samples. The concentrations ranged from 0.05 to 33 mg/kg, and the mean was 2.7 mg/kg. The mean of the products that included anionic surfactants, i.e., alkylpoly(oxyethylene)sulfates, was 7.2 mg/kg, which was higher than the 0.39 mg/kg mean for the other surfactants. Moreover, the 1,4-dioxane load/person was estimated to be 0.061 mg/day/person in Japan, which was 27 of the load from the domestic effluent.
Determination of Total Soy Isoflavones in Dietary Supplements, Supplement Ingredients, and Soy Foods by High-Performance Liquid Chromatography with Ultraviolet Detection: Collaborative Study
Authors: Collison Mark W 
Published: February 2020

Abstract
An interlaboratory study was conducted to evaluate a method for determining total soy isoflavones in dietary supplements, dietary supplement ingredients, and soy foods. Isoflavones were extracted using aqueous acetonitrile containing a small amount of dimethylsulfoxide (DMSO) and all 12 of the naturally occuring isoflavones in soy were determined by high-performance liquid chromatography (HPLC) with UV detection using apigenin as an internal standard. Fifteen samples (6 pairs of blind duplicates plus 3 additional samples) of soy isoflavone ingredients, soy isoflavone dietary supplements, soy flour, and soy protein products were successfully analyzed by 13 collaborating laboratories in 6 countries. For repeatability, the relative standard deviations (RSDr) ranged from 1.07 for samples containing over 400 mg/g total isoflavones to 3.31 for samples containing 0.87 mg/g total isoflavones, and for reproducibility the RSDR values ranged from 2.29 for samples containing over 400 mg/g total isoflavones to 9.36 for samples containing 0.87 mg/g total isoflavones. HorRat values ranged from 1.00 to 1.62 for all samples containing at least 0.8 mg/g total isoflavones. One sample, containing very low total isoflavones (&lt;0.05 mg/g), gave RSDR values of 175 and a HorRat value of 17.6. This sample was deemed to be below the usable range of the method. The method provides accurate and precise results for analysis of soy isoflavones in dietary supplements and soy foods.
A Comparative Study of First-Derivative Spectrophotometry and Column High-Performance Liquid Chromatography Applied to the Determination of Repaglinide in Tablets and for Dissolution Testing
Authors: AlKhalidi Bashar A , Shtaiwi Majed , AlKhatib Hatim S , Mohammad Mohammad , Bustanji Yasser 
Published: February 2020

Abstract
A fast and reliable method for the determination of repaglinide is highly desirable to support formulation screening and quality control. A first-derivative UV spectroscopic method was developed for the determination of repaglinide in tablet dosage form and for dissolution testing. First-derivative UV absorbance was measured at 253 nm. The developed method was validated for linearity, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ) in comparison to the U.S. Pharmacopeia (USP) column high-performance liquid chromatographic (HPLC) method. The first-derivative UV spectrophotometric method showed excellent linearity [correlation coefficient (r) = 0.9999] in the concentration range of 135 g/mL and precision (relative standard deviation &lt;1.5). The LOD and LOQ were 0.23 and 0.72 g/mL, respectively, and good recoveries were achieved (98101.8). Statistical comparison of results of the first-derivative UV spectrophotometric and the USP HPLC methods using the t-test showed that there was no significant difference between the 2 methods. Additionally, the method was successfully used for the dissolution test of repaglinide and was found to be reliable, simple, fast, and inexpensive.
Determination of Analogs of Sildenafil and Vardenafil in Foods by Column Liquid Chromatography with a Photodiode Array Detector, Mass Spectrometry, and Nuclear Magnetic Resonance Spectrometry
Authors: Choi Dong Mi , Park Sangaeh , Yoon Tae Hyung , Jeong Hye Kyoung , Pyo Jae Sung , Park Janghyun , Kim Deukjoon , Kwon Sung Won 
Published: February 2020

Abstract
Two analogs of sildenafil and vardenafil in food were detected by column liquid chromatography (LC) with a photodiode array detector. They were isolated by preparative LC; their structures were established by mass spectrometry and nuclear magnetic resonance spectrometry. One analog was found to be methisosildenafil (compound A), 5-(5-(3,5-dimethylpiperazin-1-ylsulfonyl)-2-ethoxyphenyl)-1-methyl-3-propyl-1H-pyrazolo[4,3-d]-pyrimidin-7(6H)-one. It is a sildenafil analog with a dimethylpiperazine ring substituted for the methylpiperazine group. The second analog, hydroxyvardenafil (compound B) is reported for the first time in this study. Hydroxyvardenafil's International Union of Pure and Applied Chemistry name is 2-(2-ethoxy-5-(4-(2-hydroxyethyl)-piperazin-1-ylsulfonyl)phenyl)-5-methyl-7-propylimidazo[ 1,5-f][1,2,4]triazin-4(3H)-one. The novel vardenafil analog has a hydroxyl group added to the ethylpiperazine group.
Rapid Postcolumn Methodology for Determination of Paralytic Shellfish Toxins in Shellfish Tissue
Authors: Rourke Wade A , Murphy Cory J , Pitcher Ginette , van de Riet Jeffery M , Burns B Garth , Thomas Krista M , Quilliam Michael A 
Published: February 2020

Abstract
A rapid liquid chromatographic (LC) method with postcolumn oxidation and fluorescence detection (excitation 330 nm, emission 390 nm) for the determination of paralytic shellfish toxins (PSTs) in shellfish tissue has been developed. Extracts prepared for mouse bioassay (MBA) were treated with trichloroacetic acid to precipitate protein, centrifuged, and pH-adjusted for LC analysis. Saxitoxin (STX), neoSTX (NEO), decarbamoylSTX (dcSTX), and the gonyautoxins, GTX1, GTX2, GTX3, GTX4, GTX5, dcGTX2, and dcGTX3, were separated on a polar-linked alkyl reversed-phase column using a step gradient elution; the N-sulfocarbamoyl GTXs, C1, C2, C3, and C4, were determined on a C-8 reversed-phase column in the isocratic mode. Relative toxicities were used to determine STX-dihydrochloride salt (diHCl) equivalents (STXeq). Calibration graphs were linear for all toxins studied with STX showing a correlation coefficient of 0.999 and linearity between 0.18 and 5.9 ng STX-diHCl injected (equivalent to 3.9128 g STXeq/100 g in tissue). Detection limits for individual toxins ranged from 0.07 g STXeq/100 g for C1 and C3 to 4.1 g STXeq/100 g for GTX1. Spike recoveries ranged from 76 to 112 in mussel tissue. The relative standard deviation (RSD) of repeated injections of GTX and STX working standard solutions was &lt;4. Uncertainty of measurement at a level of 195 g STXeq/100 g was 9, and within-laboratory reproducibility expressed as RSD was 4.6 using the same material. Repeatability of a 65 g STXeq/100 g sample was 3.0 RSD. Seventy-three samples were analyzed by the new postcolumn method and both AOAC Official Methods for PST determination: the MBA (y = 1.22x + 13.99, r2 = 0.86) and the precolumn LC oxidation method of Lawrence (y = 2.06x + 12.21, r2 = 0.82).
Determination of Organotins in Aquatic Food by Gas Chromatography with Pulsed Flame Photometric Detection
Authors: Yun-Feng Zhao , Kong-Xiang Zhao , Yong-Ning Wu 
Published: February 2020

Abstract
A method based on gas chromatography (GC)-pulsed flame photometric detection (PFPD) was developed to determine the levels of organotins in aquatic food. After being purified by gel-permeation chromatography in ethyl actatetetrahydrofuran, the organotin compounds were derivatized by pentylmagnesium bromide. The derivative products were injected into the GC system and detected by PFPD (sulfur mode). The method was validated by analysis of the certified reference material and spiked samples. Recoveries of organotins ranged from 84.1 to 116.6 with relative standard deviation between 1.3 and 16.0 when spiked at levels of 2, 10, and 40 g/kg. The limits of detection varied from 0.1 to 1.2 g/kg for shellfish and 0.1 to 0.5 g/kg for fish. The proposed method was suitable for determining organotins in aquatic foods.
Development and Validation of Column High-Performance Liquid Chromatographic and Derivative Spectrophotometric Methods for Determination of Levofloxacin and Ornidazole in Combined Dosage Forms
Authors: Patel Satish A , Prajapati Arun M , Patel Paresh U , Patel Natubhai J , Vaghmasi Jayesh B 
Published: February 2020

Abstract
The manuscript describes validated reversed-phase column high-performance liquid chromatographic (RP-HPLC) and first-derivative UV spectrophotometric methods for the estimation of levofloxacin (LFX) and ornidazole (ORNI) in combined dosage forms. The RP-HPLC separation was achieved on a Phenomenex C18 column (250 mm 4.6 mm id, 5 m) using KH2PO4 buffer (pH 6.8)methanolacetonitrile (70 + 15 + 15, v/v/v) mobile phase at a flow rate of 1.5 mL/min and ambient temperature (25 2&lt;sup/&gt;C). Quantification was achieved with photodiode array detection at 295 nm over the concentration range of 110 g/mL for both LFX and ORNI, with mean recovery of 101.7 0.23 and 99.23 1.57, respectively, by the RP-HPLC method. The derivative spectrophotometric method was based on the determination of both the drugs at their respective zero crossing point (ZCP). The first-order derivative spectra were obtained at N =1 (scaling factor), = 2.0 nm (wavelength interval), and the determinations were made at 310 nm (ZCP of ORNI) for LFX and 295 nm (ZCP of LFX) for ORNI over the concentration range of 240 g/mL for both LFX and ORNI. Mean recovery was 99.46 0.96 and 100.9 0.72, respectively, by the first-derivative UV spectrophotometric method. Standard and sample solutions were prepared with methanol as the solvent in both of the methods. These methods were found to be simple, accurate, precise, and sensitive and were applicable for the simultaneous determination of LFX and ORNI in combined dosage forms.
Effect of Matrix on Recovery of Biogenic Amines in Fish
Authors: Richard Nicole , Pivarnik Lori , Ellis P Christopher , Lee Chong 
Published: February 2020

Abstract
Biogenic amines, such as putrescine, cadaverine, and histamine, in fish can be indicators of spoilage and/or safety. Methanol extraction used for AOAC Official Methods 996.07 and 977.13 has resulted in low amine recoveries in fish. Extraction methodology was evaluated to improve recovery from fish tissue. Samples were evaluated for recovery of known quantities of biogenic amines added to tissue prior to extraction. Addition of 25 0.4 N HCl to the 75 methanolwater extraction solvent (according to AOAC Official Methods 996.07 and 977.13) resulted in higher recoveries (P &lt;0.05) of the biogenic amines. Putrescine recovery increased from 44 2 to 100 14 in flounder and scup, and from 53 21 to 119 27 in mackerel and butterfish; cadaverine recovery increased from 47 4 to 106 15 (flounder/scup) and 58 24 to 113 9 (mackerel/butterfish); histamine recovery increased from 54 13 to 89 28 (mackerel). MeOH extraction resulted in comparable recovery from canned tuna, indicating that protein denaturation from processing may eliminate possible matrix interference. Acidification of the solvent resulted in a more complete extraction of the added amines to fresh/frozen fish tissue. This finding could indicate that current extraction procedures may cause biogenic amines to be underestimated.
BIOPEP Database and Other Programs for Processing Bioactive Peptide Sequences
Authors: Minkiewicz Piotr , Dziuba Jerzy , Iwaniak Anna , Dziuba Marta , Darewicz Magorzata 
Published: February 2020

Abstract
This review presents the potential for application of computational tools in peptide science based on a sample BIOPEP database and program as well as other programs and databases available via the World Wide Web. The BIOPEP application contains a database of biologically active peptide sequences and a program enabling construction of profiles of the potential biological activity of protein fragments, calculation of quantitative descriptors as measures of the value of proteins as potential precursors of bioactive peptides, and prediction of bonds susceptible to hydrolysis by endopeptidases in a protein chain. Other bioactive and allergenic peptide sequence databases are also presented. Programs enabling the construction of binary and multiple alignments between peptide sequences, the construction of sequence motifs attributed to a given type of bioactivity, searching for potential precursors of bioactive peptides, and the prediction of sites susceptible to proteolytic cleavage in protein chains are available via the Internet as are other approaches concerning secondary structure prediction and calculation of physicochemical features based on amino acid sequence. Programs for prediction of allergenic and toxic properties have also been developed. This review explores the possibilities of cooperation between various programs.
Application of Mass Spectrometry to the Characterization and Quantification of Food-Derived Bioactive Peptides
Authors: del Mar Contreras María , López-Expósito Iván , Hernández-Ledesma Blanca , Ramos Mercedes , Recio Isidra 
Published: February 2020

Abstract
Biologically active peptides are of particular interest in food science and nutrition because they have been shown to play different physiological roles, including antihypertensive, opioid, antimicrobial, and immunostimulating activities. Because these peptides are generated by protein hydrolysis or fermentation, they can represent only minor constituents in a highly complex matrix and therefore, identification of biologically active peptides in food matrixes is a challenging task in food technology. In this context, mass spectrometry (MS) has developed into a necessary tool to assess quality and safety of food and, more recently, to determine the presence and behavior of functional components such as these bioactive peptides. This review highlights the existing methods based on MS to identify, characterize, and quantify food-derived biologically active peptides, taking into account the different ionization sources used for the analysis of these high-value food components. The quantitative determination of bioactive peptides in food products or biological fluids is also discussed.
Quantitative Analysis of Three Chiral Pesticide Enantiomers by High-Performance Column Liquid Chromatography
Authors: Wang Peng , Liu Donghui , Gu Xu , Jiang Shuren , Zhou Zhiqiang 
Published: February 2020

Abstract
Methods for the enantiomeric quantitative determination of 3 chiral pesticides, paclobutrazol, myclobutanil, and uniconazole, and their residues in soil and water are reported. An effective chiral high-performance liquid chromatographic (HPLC)-UV method using an amylose-tris(3,5-dimethylphenylcarbamate; AD) column was developed for resolving the enantiomers and quantitative determination. The enantiomers were identified by a circular dichroism detector. Validation involved complete resolution of each of the 2 enantiomers, plus determination of linearity, precision, and limit of detection (LOD). The pesticide enantiomers were isolated by solvent extraction from soil and C18 solid-phase extraction from water. The 2 enantiomers of the 3 pesticides could be completely separated on the AD column using n-hexane isopropanol mobile phase. The linearity and precision results indicated that the method was reliable for the quantitative analysis of the enantiomers. LODs were 0.025, 0.05, and 0.05 mg/kg for each enantiomer of paclobutrazol, myclobutanil, and uniconazole, respectively. Recovery and precision data showed that the pretreatment procedures were satisfactory for enantiomer extraction and cleanup. This method can be used for optical purity determination of technical material and analysis of environmental residues.
Determination of Nebivolol Hydrochloride and Hydrochlorothiazide in Tablets by First-Order Derivative Spectrophotometry and Liquid Chromatography
Authors: Shah Dimal A , Bhatt Kashyap K , Mehta Rajendra S , Baldania Sunil L 
Published: February 2020

Abstract
Two simple and accurate methods for analysis of nebivolol hydrochloride (NEB) and hydrochlorothiazide (HCTZ) in their combined dosage forms were developed using first-order derivative spectrophotometry and reversed-phase liquid chromatography (LC). NEB and HCTZ in their combined dosage forms (tablets) were quantified using first-derivative responses at 294.6 and 334.6 nm in the spectra of their solutions in methanol. The calibration curves were linear in the concentration range of 840 g/mL for NEB and 1060 g/mL for HCTZ. LC analysis was performed on a Phenomenex Gemini C18 column (250 4.6 mm id, 5 m particle size) in the isocratic mode with 0.05 M potassium dihydrogen phosphateacetonitrilemethanol (30 + 20 + 50, v/v/v; pH 4) mobile phase at a flow rate of 1 mL/min. Detection was made at 220 nm. Both of the drugs and the internal standard (ezetimibe) were well resolved with retention times of 5.1 min for NEB, 2.9 min for HCTZ, and 8.2 min for ezetimibe. The calibration curves were linear in the concentration range of 114 g/mL for NEB and 0.328 g/mL for HCTZ. Both methods were validated and found to be accurate, precise, and specific, and results were compared statistically. Developed methods were successfully applied for the estimation of NEB and HCTZ in their combined dosage forms.
Determination of Mepiquat Chloride Residues in Cotton and Soil by Liquid Chromatography/Mass Spectrometry
Authors: Liu Xin-Gang , Dong Feng-Shou , Li Shuo , Zheng Yong-Quan 
Published: February 2020

Abstract
A liquid chromatographic/mass spectrometric (LC/MS) method is reported for the determination of the onium-type plant growth regulator mepiquat chloride in cotton and soil. The pesticide was extracted from the sample with ethanol and water containing 2 NH4Cl. The extract was cleaned up on a solid-phase extraction C18 column, and the pesticide was determined by LC/MS. The average recoveries were 85.993.8, 81.391.7, and 78.194.7, with corresponding relative standard deviations of 3.49.6, 3.712.3, and 4.09.8, from soil, cotton leaves, and cotton seeds, respectively. A coefficient of determination of R2 0.9964 was obtained for the analyte calibration graph, from 0.05 to 100 g/mL. Decision limits, CC, and detection capability, CC, were calculated. Electrospray ionization LC/MS in the positive-ion mode (ESI+) was used to detect mepiquat chloride in extracts of soil, cotton leaves, and cotton seeds. The ion at m/z 114 in the mass spectrum was monitored.
Estimation of Berberine in Ayurvedic Formulations Containing Berberis aristata
Authors: Rout Kedar Kumar , Pradhan Subhalaxmi , Mishra Sagar Kumar 
Published: February 2020

Abstract
A sensitive, simple, rapid, and efficient high-performance thin-layer chromatographic (HPTLC) method has been developed and validated for the analysis of berberine in marketed Ayurvedic formulations containing Berberis aristata DC for regulatory purposes. Chromatography of methanolic extracts of these formulations was performed on silica gel 60 F254 aluminum-backed TLC plates of 0.2 mm layer thickness. The plate was developed up to 66 mm with the ternary-mobile phase butanolacetic acidwater (8 + 1 + 1, v/v/v) at 33 5C with 5 min of tank saturation. The marker, berberine, was quantified at its maximum absorbance of 350 nm. The limit of detection and limit of quantitation values were found to be 5 and 10 ng/spot. The linear regression analysis data for the calibration plot showed a good linear relationship with correlation coefficient 0.9994 in the concentration range of 10 to 50 ng/spot for berberine with respect to peak area. The instrumental precision was found to be 0.49 coefficient of variation (CV), and repeatability of the method was 0.73 CV. Recovery values from 98.27 to 99.11 indicate excellent accuracy of the method. The developed HPTLC method is very accurate, precise, and cost-effective, and it has been successfully applied to the assay of marketed formulations containing B. aristata for determination of berberine.
Standardization of the Ayurvedic Formulation Haridra Khanda Using High-Performance Thin-Layer Chromatography-Densitometry
Authors: Kumar Rout Kedar , Parida Sagarika , Kumar Mishra Sagar 
Published: February 2020

Abstract
The present study aimed to standardize the Ayurvedic preparation Haridra Khanda containing Curcuma longa as a major ingredient. Various physicochemical parameters such as alcohol-soluble extractive, water-soluble extractive, total ash, and acid-insoluble ash were determined according to the Ayurvedic Pharmacopoeia of India. Microscopic evaluation of the formulation revealed the presence of various diagnostic cell structures of C. longa. Trace metal analysis indicated the absence of toxic metals such as As, Cd, Hg, and Pb. High-performance thin-layer chromatographic (HPTLC) fingerprint patterns at multiple wavelengths (254, 366, and 430 nm) identified the number of components present at each wavelength. The bioactive markers curcumin (C1), demethoxycurcumin (C2), and bisdemethoxycurcumin (C3) were quantified by using a simple, rapid, and efficient HPTLC method using plates precoated with silica gel 60F254 stationary phase. The instrumental precision [coefficient of variation (CV)] was 0.51, 0.64, and 0.79% and the repeatability of the method (CV) was 0.89, 1.11, and 0.95%, respectively, for C1 to C3. Limits of detection and quantitation for compounds C1 to C3 were 20, 20, and 15 ng and 50, 40, and 50 ng, respectively. Response was a linear function in the ranges of 50350, 40240, and 50300 ng with correlation coefficient (r) 0.9998, 0.9995, and 0.9992, respectively, for C1 to C3. The mean recovery values of 99.63 (C1), 98.65 (C2), and 98.97% (C3) indicated the excellent accuracy of the method. It is shown that HPTLC can be applied successfully for the marker evaluation of the formulation containing C. longa.
High-Performance Thin-Layer Chromatography Densitometric Method for the Simultaneous Determination of Three Phenolic Acids in Syzygium aromaticum (L.) Merr. & Perry
Authors: Rastogi Subha , Pandey Madan M , Rawat Ajay K S 
Published: February 2020

Abstract
A simple, precise, and rapid high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous determination of 3 phenolic acids, i.e., gallic acid, caffeic acid, and syringic acid, in the dried buds of Syzygium aromaticum, commonly known as clove. HPTLC was performed on silica gel 60F254 plates with tolueneethyl acetateformic acid (8 2 1) mobile phase and densitometric scanning at 280 nm. The method was validated for selectivity, linearity, precision, and repeatability. Instrumental precision coefficient of variation (CV) was 0.88, 0.93, and 0.98% and repeatability of the method (CV) was 0.76, 0.64, and 0.69% for gallic acid, caffeic acid, and syringic acid, respectively. The linear concentration ranges were 4003200 ng/spot with a correlation coefficient of 0.993 for gallic acid, 4403520 ng/spot with a correlation coefficient of 0.994 for caffeic acid, and 4004000 ng/spot with a correlation coefficient of 0.993 for syringic acid. The average recoveries of gallic acid, caffeic acid, and syringic acid were 96.3, 95.7, and 92.4%, respectively. Gallic acid, caffeic acid, and syringic acid were present at levels of 1.58, 0.06, and 0.05% (w/w), respectively, in S. aromaticum. This method is simple, accurate, precise, and economical and can be used for routine quality control.