偏最小二乘紫外分光光度法同时测定甲基苯甲醛三种同分异构体

将偏最小二乘法(PLS)用于紫外分光光度数据的解析,建立了同时测定甲基苯甲醛3种同分异构体的模型。在230～304 nm范围内,将测得的48个样品的吸光度值作为校正集,另18个样品的吸光度值作为预测集用于建模。所建立的邻、间、对甲基苯甲醛模型的平均回收率分别为101.2%、100.2%和98.9%;均方根误差(RMSE)分别为0.2667、0.3853和0.2118;预测浓度范围分别为4.6～16.2μg/mL、5.8～17.4μg/mL和6.5～20.6μg/mL。讨论了混合物中3种同分异构体浓度比例对测定结果的影响,并确定了最佳的浓度比例范围。对模拟样品进行加标回收率试验。并通过与顺、反丁烯二酸两种同分异构体测定结果的比较,得出了有意义的结论。     

人工神经网络紫外光度法同时测定甲基苯甲醛的三种同分异构体及其与偏最小二乘法的比较

同分异构体的同时测定一直是分析化学领域的热点和难点问题,本文将化学计量学中的多元校正方法,如偏最小二乘法和人工神经网络法与紫外分光光度法相结合,同时测定了紫外吸收光谱严重重叠的甲基苯甲醛的三种同分异构体混合体系中各组分的含量。确定了测定的最佳波长范围为230～304 nm;测得48个混合标样的吸光度值用于建立模型,其中,邻、间、对甲基苯甲醛的浓度范围分别为6.0～15.0、7.0～16.0和8.0～19.0 μg·mL-1。7个模拟样品作为监测集用于检验所建立模型的预测性能。本文还讨论了三种组分浓度比例对所建立模型预测性能的影响并确定了可以准确测定的浓度比例范围。所建立的方法用于模拟样品的测定,其回收率在84.00%与109.60%之间。与偏最小二乘法的测定结果比较,经成对t检验表明,两种方法对邻、间甲基苯甲醛测定结果无显著性差异;而对甲基苯甲醛的测定,人工神经网络法的测定结果优于偏最小二乘法。     

基于径向基神经网络和遗传算法的槽内式选择性超声电合成甲基苯甲醛

以混合二甲苯为原料, Mn(Ⅲ)为氧化剂, 硫酸溶液为电解质, 采用槽内式超声电合成甲基苯甲醛. 探讨了选择性电合成甲基苯甲醛的可能性, 通过径向基(RBF)神经网络和遗传算法(GA)对选择性电合成甲基苯甲醛3种异构体的比例、 电流效率与混合二甲苯的用量、 硫酸浓度和电流强度的关系建立预测模型, 并运用GA确定模型中RBF神经网络的目标均方误差(Goal)和径向基函数的分布(Spread). 然后根据预测模型, 使用GA对电合成条件进行优化, 分别获得了电合成产物中对位甲基苯甲醛占优、 邻位和对位甲基苯甲醛占优以及电流效率最高时的电合成条件. 当采用上述条件进行实验时, 模型给出的预测结果分别为: 对位甲基苯甲醛占优的质量分数可达90.01%, 邻位和对位甲基苯甲醛占优的质量分数为80.38%, 电流效率达到最高时的邻位、 间位和对位甲基苯甲醛的质量分数分别为16.80%, 8.43%和74.77%; 而与之相对应的实际实验结果分别为90.10%和79.91%, 以及17.20%, 8.49%和74.31%, 二者之间的最大相对误差小于±2.24%, 表明所建立模型的预测值与实测值基本吻合.     

超声间接电氧化合成三种甲基苯甲醛

以Mn(II)/Mn(III)为氧化还原媒质，间接电氧化合成了邻、间、对位甲基苯甲 醛。在电解和合成的过程中，分别施加了超声进行反应。实验结果表明，电解的电 流效率和邻甲基苯甲醛、间甲基苯甲醛的合成产率在超声的参与下有10%左右的提 高。优化了超声电解的条件，并探讨了超声与未超声时将二甲苯的三个异构体氧化 为相应醛的难易程度。     

双波长高效液相色谱法同时测定对二甲苯及其氧化产物

采用双波长高效液相色谱法同时测定对二甲苯及其氧化产物的含量。通过二极管阵列检测器进行光谱扫描,选择在210nm下检测对甲基苯甲醇和对二甲苯,在254nm检测其余物质。优化了流动相及其梯度洗脱程序,将流动相乙腈比例降至20%~30%,各色谱峰能实现较好的分离。采用液相色谱法和气相色谱-质谱法研究了溶剂对对羧基苯甲醛和对甲基苯甲醛的影响。对羧基苯甲醛和对甲基苯甲醛可与溶剂甲醇反应生成缩醛。方法的检出限(3S/N)为0.07~0.8mg·L-1。各物质的回收率在99.2%~100%之间,相对标准偏差(n=6)小于2.5%。     

邻甲基苯甲醛的“槽内式”间接电合成

邻甲基苯甲醛的“槽内式”间接电合成;邻甲基苯甲醛; 氧电还原; 氧还电对V5+/V4+; 邻二甲苯; 电解     

荧光光度法同时测定邻苯二酚、间苯二酚与对苯二酚

将一种直接信号校正(DOSC)-小波包变换(WPT)-偏最小二乘法(PLS)(DOSC-WPT-PLS)新方法用于解析荧光光谱严重重叠的邻苯二酚?间苯二酚和对苯二酚混合物,并对其进行测定。该法将DOSC、WPT及PLS 3种方法结合从而提高了获取特征信息的能力和回归质量。DOSC方法用于除去与浓度无关的结构噪音。利用WPT的时域和频域局部化的特点改进了除噪质量和数据压缩及信息提取能力。PLS方法用于多变量校准和噪音消除。处理该3种组分的荧光光谱数据,并实现了3种化合物的同时测定。设计了PDOSCWPTPLS程序执行相关计算,并对以上3种化学计量学方法进行了比较,其总体相对预测标准偏差分别为4.3%、7.7%、11.5%,结果表明DOSC-WPT-PLS法优于WPT-PLS法和PLS法。将该法用于测定自来水中邻苯二酚?间苯二酚和对苯二酚的含量,其回收率分别为99%~110%?95%~108%和98%~104%,结果满意。     

电合成产物苯甲醛的高效液相色谱法测定

建立了一种用高效液相色谱法(HPLC)测定电合成产物中苯甲醛的方法.采用Kronmsil C(18)色谱柱(5μm,250 mm×4.6 mm I.d.),流动相为甲醇,检测波长为250 nm,外标法定量.苯甲醛的质量浓度在2.0-70.0 mg/L范围内线性关系良好,其相关系数r=0.9998(n=3);将本法应用于电合成产物中苯甲醛的测定,其加标回收率为93.0%～97.0%,相对标准偏差为0.05%～1.2%.     

气相色谱法分析生产过程中的邻甲基苯胺

气相色谱法测定工业生产过程中邻甲基苯胺及其杂质邻硝基甲苯、间甲基苯胺、对甲基苯胺的含量。4种物质的浓度与色谱峰面积呈良好的线性关系,测定结果与标准值基本一致。邻甲基苯胺、邻硝基甲苯、间甲基苯胺、对甲基苯胺的RSD分别为0.0025%、1.4081%、0.9929%、1.1365%,检出限分别为0.065、0.044、0.062、0.056mg/L。     

烟酸直接电氧化合成反应液的全分析

将非水溶液电位滴定法和紫外分光光度法相结合,对3-甲基吡啶(3-MP)直接电氧化合成烟酸反应液中烟酸、H2SO4、3-MP进行了全分析。以二甲基甲酰胺(DMF)作溶剂进行非水溶液电位滴定,可准确测定烟酸和H2SO4的含量,测定结果的相对标准偏差分别为2．08％和0．908％;平均回收率分别为101％和99．9％。在262nm波长下进行紫外检测,烟酸和3-MP在H2SO4水溶液中吸光度具有良好的加和性,烟酸、3-MP的浓度在0．0610～0．122mmol／L范围内与吸光度呈很好的直线关系,方法的相对标准偏差为3．52％,平均回收率为99．9％。     

对二甲苯电合成法制备对甲苯甲醛的气相色谱分析

研究了对甲苯甲醛的气相色谱分析条件。分别选用８％ＯＶ－２１０,１０％ＱＦ－１和８％ＤＣ－２００为固定相测定对甲基苯甲醛的含量。结果表明：本方法快速,准确,标准偏差小于０．２％,回收率为１００．５％￣１０１．０％。     

偏最小二乘紫外分光光度法同时测定丁烯二酸的顺反异构体

将偏最小二乘法用于紫外分光光度分析,在pH=1.4的磷酸溶液中,同时测定了丁烯二酸的顺、反异构体。确定了测定的最佳波长范围为190～268nm;测得23个混合标样的吸光度值用于建立模型,顺、反丁烯二酸的浓度范围为3.0～14.0mg/L和1.0～13.0mg/L。所建立的测定二者模型的相关系数分别为0.9951和0.9983;平均回收率分别为100.8%和100.7%;均方根误差(RMSE)分别为0.3667和0.2233;预测相对误差(REP)分别为5.05%和3.49%。对3个批次反丁烯二酸样品的测定结果与高效液相色谱法的测定结果进行比较,经成对t检验表明,两种方法的测定结果无显著性差异。     

Chemometrics-assisted simultaneous determination of atenolol and chlorthalidone in synthetic binary mixtures and pharmaceutical dosage forms

Resolution of binary mixtures of atenolol (ATE) and chlorthalidone (CTD) with minimum sample pre-treatment and without analyte separation has been successfully achieved, using a new and rapid method based on partial least squares (PLS1) analysis of UV spectral data. The simultaneous determination of both analytes was possible by PLS1 processing of sample absorbances between 255 and 300 nm for ATE and evaluation of absorbances in the 253–268 nm region for CTD. The mean recoveries for synthetic samples were 100.3±1.0% and 100.7±0.7% for ATE and CTD, respectively. Application of the proposed method to two commercial tablet preparations in the content uniformity test showed them to contain 103.5±0.8% and 104.9±1.8% ATE respectively, as well as 103.4±1.2% and 104.5±2.2% CTD. Use of this method also allowed the elaboration of dissolution profiles of the drugs in two commercial combined formulation products, through the simultaneous determination of both drugs during the dissolution test. At the dissolution time of 45 min specified by USP XXIV, both pharmaceutical formulations complied with the test.     

Simultaneous spectrophotometric determination of carbamazepine and phenytoin in serum by PLS regression and comparison with HPLC

Carbamazepine (CBZ) and phenytoin (PHT) are two antiepileptic drugs which are used simultaneously. In this paper a partial least-squares (PLS) calibration method is described for the simultaneous spectrophotometric determination of CBZ and PHT in plasma. Standard binary mixtures of CBZ and PHT have been resolved by application of PLS-1 to their UV spectra. Then, the binary standard solutions, spiked to plasma, were prepared and after the extraction of the drugs, their corresponding UV spectrum were analyzed by PLS regression to calculate the concentration of drugs in unknown plasma. A leave one out cross-validation procedure was employed to find the optimum numbers of latent variables using PRESS. A HPLC method was also applied for simultaneous determination of two drugs in the plasma and in methanol. The mean recoveries obtained by PLS were 98.4 and 98.2 for CBZ and PHT and those obtained by HPLC were 100.1 and 101.7, respectively. Although, the HPLC method showed better performance than PLS, it was found that the results obtained by PLS were comparable with those obtained by HPLC method.     

偏最小二乘-分光光度法同时测定芦丁与槲皮素的方法研究

芦丁和槲皮素在紫外区的最大吸收波长接近,吸收光谱严重重叠,普通光度法分析难以实现两者的直接测定.该文通过测定以1∶4甲醇-水为溶剂的芦丁、槲皮素标准混合溶液在200～500 nm波长范围的吸收光谱,采用偏最小二乘法(PLS法)建立校正模型,对样品中的芦丁和槲皮素的含量进行预测,建立了偏最小二乘-分光光度法同时测定芦丁和...     

Chemometrics-assisted spectrophotometric methods for simultaneous determination and complexation study of Fe(III), Al(III) and V(V) with morin in micellar media

Evolutionary factor analysis (EFA) and rank annihilation factor analysis (RAFA) were applied to resolve the two-way equilibrium spectrophotometric data belonging to the complexes of Fe(III), Al(III) and V(V) with morin (3,5,7,20,40-penta hydroxy flavone) as chelating agent in triton X-100 micellar media. Then, partial least square regression combined with genetic algorithm for wavelength selection (GA-PLS) was used for simultaneous determination of the metal ions. The parameters controlling behavior of the system were investigated and optimum conditions were selected. The predictive abilities of partial least squares regression (PLS) and genetic algorithm-partial least squares regression (GA-PLS) were examined in simultaneous determination of ternary mixtures of metal ions over the concentration range of 17.0-170.0ngml(-1), 25.0-180.0ngml(-1) and 40.0-325.0ngml(-1) for Fe(III), Al(III) and V(V), respectively. The relative standard errors for prediction of the ions in synthetic mixtures were lower than 5% and the mean recoveries in the tap water spiked samples were 104.2 and 101.7% for PLS and GA-PLS, respectively.     

Comparison of UV derivative-spectrophotometry and partial least-squares (PLS-1) calibration for determination of methotrexate and leucovorin in biological fluids

Binary mixtures of methotrexate (MTX) and leucovorin (LV) have been resolved by application of first-derivative spectrophotometry and partial least squares calibration (PLS-1). By measuring the first-derivative signals of MTX and LV at 354 and 300 nm, respectively, simultaneous determination was possible. The mean recoveries for urine samples were 91 and 96% for MTX and LV, respectively. Partial least squares (PLS-1) multivariate calibration has been applied to the determination of these compounds in serum and in urine without pretreatment of the samples. The absorption spectra of serum or urine samples spiked with methotrexate and/or leucovorin, were used to optimize the calibration matrixes by the PLS-1 method. The sensitivity and selectivity of the proposed procedures were calculated. Mean recoveries were 101 and 97% for MTX and LV, respectively, for serum samples, and 101 and 98% for MTX and LV, respectively, for urine samples.     

A PLS-based extractive spectrophotometric method for simultaneous determination of carbamazepine and carbamazepine-10,11-epoxide in plasma and comparison with HPLC

Carbamazepine (CBZ) undergoes enzyme biotransformation through epoxidation with the formation of its metabolite, carbamazepine-10,11-epoxide (CBZE). A simple chemometrics-assisted spectrophotometric method has been proposed for simultaneous determination of CBZ and CBZE in plasma. A liquid extraction procedure was operated to separate the analytes from plasma, and the UV absorbance spectra of the resultant solutions were subjected to partial least squares (PLS) regression. The optimum number of PLS latent variables was selected according to the PRESS values of leave-one-out cross-validation. A HPLC method was also employed for comparison. The respective mean recoveries for analysis of CBZ and CBZE in synthetic mixtures were 102.57 (+/-0.25)% and 103.00 (+/-0.09)% for PLS and 99.40 (+/-0.15)% and 102.20 (+/-0.02)%. The concentrations of CBZ and CBZE were also determined in five patients using the PLS and HPLC methods. The results showed that the data obtained by PLS were comparable with those obtained by HPLC method.