Electrochemical studies and differential pulse polarographic analysis of lansoprazole in pharmaceuticals

The electrochemical reduction of lansoprazole was investigated by cyclic voltammetry and direct current and differential pulse polarography. The reduction potential was -1.32 V vs. Ag/AgCl with a dropping mercury electrode in a supporting electrolyte consisting of phosphate buffer (pH 9.0)-tetramethylammonium iodide (4 + 1). The reversibility of the electrode reaction and the type of limiting current were studied. The temperature coefficient and the diffusion constant were determined. A mechanism for the electrode reaction was proposed. A new simple and sensitive differential pulse polarographic method was also developed for the quantification of lansoprazole. A linear calibration graph was obtained in the range 0.04-11.35 micrograms ml-1. The limit of detection was 0.03 microgram ml-1 and the intra- and inter-day precisions were 0.84-2.32 and 0.72-3.09%, respectively. The developed method was applied to six different commercial pharmaceutical capsule preparations containing enteric-coated granules. The relative standard deviations ranged from 1.36 to 2.85%. Recovery studies for the accuracy of the method were performed by adding a synthetic mixture to known amounts of lansoprazole and the mean recovery was 100.45%. The data obtained from commercial preparations were compared with those from a published spectrophotometric method. No difference was found statistically.     

The differential pulse polarographic determination of trace amounts of tin and its application to zinc-aluminium alloys

A differential pulse polarographic procedure for the determination of 0.001-0.02% of tin in zinc-aluminium alloys is described. The tin is first separated from interfering elements such as copper and lead by homogeneous co-precipitation with aluminium succinate. The tin is determined polarographically in a 1M hydrochloric acid + 4M ammonium chloride electrolyte. After the tin has been masked with alkaline citrate a second polarogram is recorded to ascertain whether residual lead is present and, if so, a correction is applied.     

Chemometric Assisted UV-Spectrophotometric Methods Using Multivariate Curve Resolution Alternating Least Squares and Partial Least Squares Regression for Determination of Beta-Antagonists in Formulated Products: Evaluation of the Ecological Impact

In this study, UV-spectrophotometry coupled with chemometrics has been utilized to enhance the sustainability of quality control analysis of beta antagonists. First, we developed and optimized two eco-friendly chemometric-assisted methods without preliminary separation utilizing (1) multivariate curve resolution alternating least squares (MCR-ALS) and (2) well-established partial least squares regression (PLSR) multivariate calibration for the resolution and quantification of the most commonly prescribed beta antagonists in active pharmaceutical ingredients or commercial pharmaceutical products. The performance of the two proposed chemometric methods was computed and compared. Second, a comprehensive qualitative and quantitative evaluation of the eco-friendliness of the developed methods was performed utilizing the following greenness assessment tools: Green Analytical Procedure Index (GAPI), Analytical Eco-scale assessment (AES) tool, Raynie and Driver’s assessment tool and Analytical GREEnness Metric (AGREE). The models showed satisfactory recovery with a range from 99.83% to 101.12% for MCR-ALS and from 99.66% to 101.54% for PLSR. The optimized models were employed for green analysis of the investigated beta-blockers in single or co-formulated formulations without prior separation. The predictivity of the proposed MCR-ALS and the well-established PLSR method were very comparable. Nevertheless, the MCR-ALS method has the ability to recover the pure spectra of the studied analytes and the interferences as well. The proposed chemometric methods are fast, precise and do not need any sample pretreatment. In addition, they can be used as a benign substitute for the traditional methods used for the analysis of the investigated drugs in pharmaceutical products without harmful impacts on human health and the environment. They also provide advantages in terms of low solvent usage, reduced energy consumption and short analysis time, making them a safe and sustainable approach for quality control analysis.     

偏最小二乘法辅助分光光度法同时测定痕量锰、铁、铜和锌

痕量Mn（Ⅱ）、Fe（Ⅲ）、Cu（Ⅱ）和Zn（Ⅱ）与2－（5－溴－2－吡啶偶氮）－5－二乙氨基苯酚和聚乙二醇辛基本基醚在pH8．8发生高灵敏的显色反应，所形成的三元胶束络合物的吸收光谱严重重叠，用偏最小二乘法（PLS）辅助分光光度法成功地同时测定了模拟试样及铝合金和饲料添加剂中上述四种痕量组分。结果表明，PLS法是化学计量学法中一种可适用于基体较复杂的实际试样中痕量组分同时分光光度测定的优良的多元计算方法。     

Multivariate Prediction by Using Conventional and Derivative Partial Least Squares Statistics in a Complex Chemical System. Ternary Metals Mixture Resolution

Abstract

The quantitative prediction abilities of Partial Least Squares methods (type 1 and 2) for analysis of conventional and derivative absorption spectra are compared. The influence of the band width and of the spectral overlapping on the capacity of prediction of PLS in both cases are described and ternary mixtures of metals are resolved. To obtain analytes with adequate spectral characteristics the resolution of the metals has been accomplished by using the reaction with a cyclic hydroxamic acid and extraction into methyl isobutyl ketone (MIBK). Significant advantages have been found by application of differentiation techniques in combination with PLS-1 method.

     

偏最小二乘法用于荧光光度法同时测定铈,镨,铽

本文将偏最小二乘法(PLS)用于荧光光度法同时测定铈、镨、铽。对荧光光度法的测定条件及PLS法中系列校准样品的实验设计及测量波长点的选择等进行了试验和讨论。所建立的方法用于天然混合稀土氧化物中铈、镨、铽的测定,获得较满意的结果     

Spectrophotometric, differential pulse polarographic and differential pulse voltammetric monitoring of the chemical destruction of the anti-tumour pharmaceuticals 6-mercaptopurine, 6-thioguanine and melphalane

A new method has been developed for the destruction of 6-mercaptopurine, 6-thioguanine and melphalane in laboratory waste, based on oxidation of these substances by potassium permanganate in sulphuric acid medium. To study the effectiveness of the decontamination, spectrophotometric and differential-pulse polarographic methods have been developed for the determination of 6-mercaptopurine and 6-thioguanine and spectrophotometric and differential-pulse voltammetric methods for melphalane. These techniques have been employed to demonstrate that the effectiveness of the proposed method is around 99.8%. Its usefulness for the destruction of various types of expired pharmaceuticals has been demonstrated.     

The application of 2,4,6-trinitrobenzene-1-sulphonic acid in the differential pulse polarographic determination of amines

The differential pulse polarographic behaviour of 2,4,6-trinitrophenyl (TNP) derivatives of several primary amines and amino acids was investigated in the presence of sulphite ion. All the derivatives produced a polarographic peak for their complexes with sulphite (1 × 10^?2 M) in pH 8.0 phosphate buffer (0.05 M)/0.1 M potassium chloride. The derivatives of proteins and peptides did not give such a peak. A 5-min reaction time at room temperature (or 50°C for lysine) and pH 10.5 using 1 × 10^?4 M 2,4,6-trinitrobenzene-1-sulphonic acid provides the optimal conditions for the determination of 5 × 10^?6?2.5 × 10^?5 M amines. The relative standard deviation for determining 1 × 10^?5 M glycine (n = 5) was 1%.     

Determination of Quercetin and Luteolin in Paprika Samples by Voltammetry and Partial Least Squares Calibration

Quercetin and luteolin are flavonoids with beneficious properties, which are present in paprika. In this work, both have been determined in paprika by using electrochemistry combined with chemometrics. The electrochemical oxidation mechanisms of both analytes have been studied through sampled direct current (DC) voltammetry, differential pulse voltammetry (DPV) and Square Wave Voltammetry (SWV), making use of a glassy carbon electrode. The final technique selected for the quantification was DPV due to its high repeatability with respect SWV. The chemical variables and the instrumental parameters were optimized and the final conditions employed were ethanol: water (20 : 80), 0.75 mol dm⁻³ of HCl, and a pulse amplitude of 50 mV. Due to the facts that oxidation potential of both analytes were quite similar, their DPV peaks were overlapped, and also because the analytes interaction during the electrochemical process causes a non‐additivity of the signals, they could not be quantified separately by direct measurement of peak intensity. For this reason, a chemometric algorithm was applied (partial least squares (PLS) regression in its modality PLS‐2). In the case of validation samples, appropriate sets of calibration and validation were built and good results were obtained. This methodology was applied to real paprika samples and the results were similar to those obtained with a HPLC method previously reported.     

Discrimination of Human and Nonhuman Blood by Raman Spectroscopy and Partial Least Squares Discriminant Analysis

A novel method is reported to discriminate human and animal blood by Raman spectroscopy without complex sample preparation. A partial least squares discriminant analysis model was constructed from a calibration set of Raman spectra from three species of animal blood using 785-nm laser excitation. The discrimination between human and nonhuman blood was calculated by three sigma. Various performance measures, including a blind test and external validation, confirmed the discriminatory performance of the chemometric model. The model provided 100% accuracy in its differentiation between human and nonhuman blood. These results demonstrate that Raman spectroscopy is a promising tool for the discrimination of animal and human blood.     

偏最小二乘法及主组分回归法用于药物组分的测定

本文研究了多元校准方法——偏最小二乘法(PLS)和主组份回归法(PCR)在药物多组份光度分析中的应用,获得了较满意的结果。而且在系列校准样品的实验设计、交叉证实法确定最佳因子数以及空缺组份体系的分析等方面进行了探讨。     

偏最小二乘催化极谱法同时测定铂,钯,铑

应用Ｍ２７３Ａ电化学系统中的线性扫描技术，确定了０．７５ｍｏｌ／ＬＨ２ＳＯ４－１．５％ＮＨ４Ｃｌ－２．８ｍｍｏｌ／Ｌ（ＣＨ２）６Ｎ４－０．００２５％Ｎ２Ｈ４．Ｈ２ＳＯ４为偏最小二乘极谱法同时测定Ｐｔ、Ｐｄ、Ｒｈ的最佳极谱体系。Ｐｔ、Ｐｄ、Ｒｈ的线性范围为３．２ｍｇ／Ｌ、０－１５．０ｍｇ／Ｌ和０－１．０ｍｇ／Ｌ。模拟样品及实际样品的回收率在９０．３－１０７．７％之间。     

Rapid Determination of Cotton Content in Textiles by Near-Infrared Spectroscopy and Interval Partial Least Squares

Textile products must be marked by fabric type and composition on the label and cotton is by far the most important fiber in the industry and often needs fast quantitative analysis. The corresponding standard methods are very time-consuming and labor-intensive. The work focuses on exploring the feasibility of combining near-infrared (NIR) spectroscopy and interval-based partial least squares (iPLS) for determining cotton content in textiles. Three types of partial least square (PLS)-based algorithms were used for experimental measurements. A total of 91 cloth samples with cotton content ranging from 0 to 100% (w/w) were collected and all compositions are commercially available on the market in China. In all cases, the original spectrum axis was split into 20 subintervals. As a result, three final models, i.e., the iPLS model on a single subinterval, the backward interval partial least squares (biPLS) model on the region remaining six subintervals, and the moving window partial least squares (mwPLS) model with a window of 75 variables, achieved better results than the full-spectrum PLS model. Also, no obvious differences in performance were observed for the three models. Thus, either iPLS or mwPLS was preferred considering their simplicity, which suggested that iPLS and mwPLS combined with NIR technique may have potential for the rapid determination of the cotton content of textile products with comparable accuracy to standard procedures. In addition, this approach may have commercial and regulatory advantages that avoid labor-intensive and time-consuming chemical analysis.     

偏最小二乘分光光度法同时测定镍基合金中的铈和钇

以对乙酰基偶氮氯膦（ＣＰＡｐＡ）为显色剂，研究了同时测定Ｃｅ和Ｙ的最佳条件，由于二者吸收光谱严重重叠，本文运用偏最小二乘法实现了Ｃｅ和Ｙ的同时测定，结果满意。     

微分脉冲溶出伏安-偏最小二乘法同时测定代森锌和代森锰

采用循环伏安法讨论了两种常用的杀菌剂代森锰和代森锌在汞电极上的电化学还原反应机理,发现它们均具有良好的的伏安还原峰.采用微分脉冲溶出伏安法研究本体系时,获得的代森锰和代森锌的线性范围分别为0.005～0.07 mg/L和0.02～0.24 mg/L;检出限分别为4.10和12.8μg/L.由于这两种杀菌剂的分子结构很相似,它们的伏安波谱峰重叠严重,采用常规方法很难对它们分别进行测定.为解决波谱重叠的问题,本研究采用主成分回归和偏最小二乘法对波谱进行解析.结果表明,偏最小二乘法能得到较好的定量结果.利用本方法对几种蔬菜和水果样品进行分析,三氯甲烷作萃取剂的萃取率最大,回收率在95.5％～103％之间.     

偏最小二乘法在多组分阳极溶出伏安分析中的应用—铜,锑,铋的同时测定

本文利用微分脉冲阳极溶出伏安法对微量铜、锑、铋混合溶液进行同进分析，实验在盐酸－氯化钠介质中进行，悬汞电极作工作电极，在－４００ｍＶ处富集电解５ｍｉｎ，然后由－４００ｍＶ向０Ｖ作微分脉冲溶出伏安扫描，扫描速度为２ｍＶ／ｓ，脉冲振幅为４０ｍＶ，由于计算机采集溶出伏安数据后采用偏最小二乘法计算并建立数学模型，然后据此模型对未知溶液进行定量分析，获得了较好的结果。