Journal of Chemical Metrology
A scientific open access journal in the field of analytical chemistry and accreditation
Journal of Chemical MetrologyA scientific open access journal in the field of analytical chemistry and accreditation
Achievement of antioxidants from Abelmoschus esculentus L. seeds using ultrasound-assisted extraction optimized by the help of experimental design approach
Developments of food supplements and nutraceuticals from different natural origins require the use of some extraction methods. The success of the procedure relies on theefficiency of the extraction methods. Therefore, extraction methods need to be optimized. This work aimed for the determination of optimal conditions of ultrasonic-assisted extraction (UAE) of antioxidant constituents from okra (Abelmoschus esculentus L.) seeds which contain high contents of polysaccharides, polyphenols and flavonoids using response-surface methodology based on Box-Behnken experimental design (BBD). The independent variables of UAE were extraction time (Et, 10-20 min), extraction solvent composition (EC, 50-100% methanol) and extraction solvent volume (EV, 10-20 mL). 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity, 2,2'-azinobis- (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging activity and N,N-dimethyl-p-phenylenediamine dihydrochloride (DMPD) radical-scavenging activity were dependent variables. Optimal extraction conditions for UAE from okra seed were: 20 mL volume of 70% methanol at 10 min extraction time for DPPH inhibition; 20 mL volume of 50% methanol at 20 min for ABTS inhibition; 15 mL volume of 55% methanol at 12 min for DMPD inhibition. Under these optimum extraction conditions, the effectiveness of UAE of okra seed was successfully revealed. So, this practical extraction technique can be widely used for the achievement of dietary supplements and nutraceuticals.DOI http://doi.org/10.25135/jcm.49.20.07.1742 (DOI number will be activated after the manuscript has been available in an issue.) Keywords Abelmoschus esculentus L. seed okra ultrasound-assisted extraction box-Behnken Design response surface methodology Available online: November 09, 2020 DETAILS DOWNLOAD PDF © ACG Publications. All rights reserved.
Metrology in chemistry: some questions and answers
This article presents some typical questions from practitioners, trying to implement metrological concepts in their everyday chemical analysis work, and answers to them by the authors, in the context of the authors’ pragmatic view on applying the metrological principles to chemical analysis. Several of the presented questions are staples at training seminars and during on-line courses. The answers to the questions reflect the authors’ opinions and are not always fully in line with the generally accepted positions.DOI http://doi.org/10.25135/jcm.18.104.22.1688 (DOI number will be activated after the manuscript has been available in an issue.) Keywords Metrology in chemistry reference values repeatability intermediate precision constant improvement Available online: November 03, 2020 DETAILS DOWNLOAD PDF © ACG Publications. All rights reserved.
Certification of sodium benzoate solution reference material by HPLC-UV, LC-MS/MS and UV-VIS-NIR spectrophotometry for food and drug analysis
Sodium benzoate is one of the most widely used food perseverates and has to be used in regulated amounts to avoid its harmful health effects. Reviewing the scientific literature for traceability of the analytical measurement results of sodium benzoate in various food and drug applications to the SI units, it has been found that no scientific details of certification of sodium benzoate CRMs used for the calibration of measuring equipment are published. For this reason, the national metrology institute of Saudi Arabia (SASO/NMCC) certifies a sodium benzoate solution reference material. In this work, sodium benzoate was synthesized, purified and a batch solution reference material was prepared as 1014.47 mg/kg then homogenized and bottled. Homogeneity and stability of the candidate RM were assessed and the results obtained showed that the material is sufficiently homogeneous and stable. Characterization of the reference material was carried out by HPLC-UV, LC-MS/MS and UV-VIS-NIR spectrophotometer as three independent methods. The certified value was derived by combining data from the three methods using the weighted mean approach and was found 1016.13 mg/kg. The certified uncertainty was calculated as weighted uncertainty and was found 10.47 mg/kg (1.03%). Sources of this uncertainty were identified from the characterization, uchar, homogeneity, uhom, and long-term stability, ults, as well as the bias allowance, B.DOI http://doi.org/10.25135/jcm.48.20.08.1780 (DOI number will be activated after the manuscript has been available in an issue.) Keywords CRM sodium benzoate homogeneity stability characterization certified value Available online: October 18, 2020 DETAILS DOWNLOAD PDF © ACG Publications. All rights reserved.
UV-spectrophotometry-assisted chemometric methods for simultaneous determination of ambroxol hydrochloride and doxofylline in pharmaceutical formulation
Two methods, ratio spectra derivative method and partial least squares regression (PLS) were developed for the simultaneous estimation of ambroxol hydrochloride and doxofylline in combined dosage form. In the first method, ratio spectra derivative method, analytical signals were measured at the wavelengths corresponding to either maximums or minimums for both drugs in the first derivative spectra of the ratio spectra obtained by dividing the standard spectrum of one of two drugs in water. Partial least squares regression (PLS) was used for data analysis of and the parameters of the chemometry procedures were optimized. In this study, the simultaneous determination of ambroxol hydrochloride and doxofylline in pharmaceuticals by chemometric approaches using UV spectrophotometry has been reported. Spectra of ABH and DOX were recorded at several concentrations within their linear ranges between 2-12 μg/mL and 15-40 μg/mL respectively and applied to pharmaceutical formulation, tablet, with no interference with excipients as indicated by the results of the recovery study. The proposed methods are simple, rapid and can be easily used in the quality control of drugs as alternative analytical tools.DOI http://doi.org/10.25135/jcm.47.20.05.1638 (DOI number will be activated after the manuscript has been available in an issue.) Keywords Ambroxol hydrochloride doxofylline partial least squares ratio derivative spectrophotometry validation Available online: October 05, 2020 DETAILS DOWNLOAD PDF © ACG Publications. All rights reserved.