Simultaneous determination of tartrazine and sunset yellow in cosmetic products by first-derivative spectrophotometry

A spectrophotometric method for the simultaneous determination of Tartrazine (TT) and Sunset Yellow (SY) in cosmetic products has been developed. An extraction process was carried out using methylene chloride and the colouring matters were measured in the aqueous phase formed, the other components of the sample remaining in the organic phase. The applicable concentration ranges were 0.5–10 ug/ml TT and 0.5–12 g/ml SY. The detection limits were 26 and 11 ng/ml and the relative standard deviations were 1.0 and 0.9% for TT and SY, respectively. The method was applied to the determination of both compounds in cosmetics.     

Simultaneous determination of tartrazine and sunset yellow by derivative spectrophotometry and ratio spectra derivative

Two methods for determining Tartrazine and Sunset Yellow in mixtures by first derivative spectrophotometry and by first derivative of the ratio spectra are described. The procedures do not require any separation step. By the first method, the measurements are obtained in the zero-crossing wavelengths and the calibration graphs are linear up to 20 microg/ml of Tartrazine and up to 40 microg/ml of Sunset Yellow. The determinations of Tartrazine and Sunset Yellow are also done by the first derivative of the ratio spectra. The methods are applied for determining both compounds in four commercial food products.     

Simultaneous fluorimetric determination of acetylsalicylic acid metabolites in urine by partial least squares multivariate calibration

A method is described for the simultaneous determination of the main urinary acetylsalicylic acid (aspirin) metabolites, salicyclic, salicyluric and gentisic acids, based on their native fluorescence. The urine was extracted into diethyl ether in acid medium, and back-extracted with glycine/sodium hydroxide buffer solution at pH 9.4. A comparative study of the results found using the excitation, the emission and the combination of the excitation plus the emission spectral data, as analytical signals, was performed. The data set, composed of the excitation plus the emission spectra, was selected as the analytical signal. The optimum wavelengths to record the excitation (_em=444 nm) and the emission spectra (_ex=323 nm) were selected to maximize the contribution from gentisic acid, which is the minor urinary metabolite. Partial least squares (PLS-1) multivariate calibration was then applied for the determination. Recovery values from urine samples spiked with salicyclic, salicyluric and gentisic acids varied from 90.1 to 97.6% (mean 93.6%), from 90.0 to 110% (mean 97.9%) and from 89.9 to 104.7% (mean 98.5%), respectively.     

Simultaneous fluorimetric determination of acetylsalicylic acid metabolites in urine by partial least squares multivariate calibration

A method is described for the simultaneous determination of the main urinary acetylsalicylic acid (aspirin) metabolites, salicyclic, salicyluric and gentisic acids, based on their native fluorescence. The urine was extracted into diethyl ether in acid medium, and back-extracted with glycine/sodium hydroxide buffer solution at pH 9.4. A comparative study of the results found using the excitation, the emission and the combination of the excitation plus the emission spectral data, as analytical signals, was performed. The data set, composed of the excitation plus the emission spectra, was selected as the analytical signal. The optimum wavelengths to record the excitation (lambda(em)=444 nm) and the emission spectra (lambda(ex)=323 nm) were selected to maximize the contribution from gentisic acid, which is the minor urinary metabolite. Partial least squares (PLS-1) multivariate calibration was then applied for the determination. Recovery values from urine samples spiked with salicyclic, salicyluric and gentisic acids varied from 90.1 to 97.6% (mean 93.6%), from 90.0 to 110% (mean 97.9%) and from 89.9 to 104.7% (mean 98.5%), respectively.     

Simultaneous spectrophotometric determination of ethinylestradiol and levonorgestrel by partial least squares and principal component regression multivariate calibration

Two spectrophotometric methods for the determination of Ethinylestradiol (ETE) and Levonorgestrel (LEV) by using the multivariate calibration technique of partial least square (PLS) and principal component regression (PCR) are presented. In this study the PLS and PCR are successfully applied to quantify both hormones using the information contained in the absorption spectra of appropriate solutions. In order to do this, a calibration set of standard samples composed of different mixtures of both compounds has been designed. The results found by application of the PLS and PCR methods to the simultaneous determination of mixtures, containing 4–11 μg ml⁻¹ of ETE and 2–23 μg ml⁻¹ of LEV, are reported. Five different oral contraceptives were analyzed and the results were very similar to that obtained by a reference liquid Chromatographic method.     

Simultaneous spectrophotometric determination of Tartrazine, Sunset Yellow and Ponceau 4R in commercial products by partial least squares and principal component regression multivariate calibration methods

Three multivariate calibration methods, partial least squares (PLS-1 and PLS-2) and principal component regression (PCR), were proposed and successfully applied to the simultaneous determination of three dyes, Tartrazine (E-102), Sunset Yellow (E-110) and Ponceau 4R (E-124) in mixtures by ultraviolet-visible absorption spectrophotometry. The designed and optimized training set of calibration was applied to the determination of the three dyes in several synthetic mixtures, containing 1.6–20.0 mg/L of Tartrazine, 3.2–40.0 mg/L of Sunset Yellow and 3.2– 36.0 mg/L of Ponceau 4R. 94.5–105.3% recovery values were obtained. Three commercial foods that contained the three dyes were also satisfactorily analyzed without separation step. The results obtained by the application of the three chemometric approaches in the commercial products are discussed and compared with those obtained by an HPLC method and very similar values were found by all methods. Repeatability and reproducibility studies (with the Student’s and F tests) were achieved over two series of nine standards for each dye, showing no significant differences at the 95% confidence level. Received: 27 October 1997 / Revised: 9 January 1998 / Accepted: 24 January 1998     

Simultaneous spectrophotometric determination of Tartrazine, Sunset Yellow and Ponceau 4R in commercial products by partial least squares and principal component regression multivariate calibration methods

Three multivariate calibration methods, partial least squares (PLS-1 and PLS-2) and principal component regression (PCR), were proposed and successfully applied to the simultaneous determination of three dyes, Tartrazine (E-102), Sunset Yellow (E-110) and Ponceau 4R (E-124) in mixtures by ultraviolet-visible absorption spectrophotometry. The designed and optimized training set of calibration was applied to the determination of the three dyes in several synthetic mixtures, containing 1.6–20.0 mg/L of Tartrazine, 3.2–40.0 mg/L of Sunset Yellow and 3.2– 36.0 mg/L of Ponceau 4R. 94.5–105.3% recovery values were obtained. Three commercial foods that contained the three dyes were also satisfactorily analyzed without separation step. The results obtained by the application of the three chemometric approaches in the commercial products are discussed and compared with those obtained by an HPLC method and very similar values were found by all methods. Repeatability and reproducibility studies (with the Student’s and F tests) were achieved over two series of nine standards for each dye, showing no significant differences at the 95% confidence level.     

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。     

Simultaneous determination of domperidone and cinnarizine in a binary mixture using derivative spectrophotometry,partial least squares and principle component regression calibration

This work is concerned with the simultaneous determination of domperidone maleate (DOM) and cinnarizine (CINN) in a binary mixture form, without previous separation, by two different techniques. The first method is the application of derivative spectrophotometry where the linearity range and percentage recoveries for DOM and CINN were 2.5-30 micro g mL(-1), 5-25 micro g mL(-1) and 100.06+/-1.157, 99.93+/-1.377, respectively. The second method depends on the application of partial least squares (PLS) and principle component regression (PCR) models. A training set consisting of 10 mixtures containing 5-20 micro g mL(-1) for each component was used for the construction of the PCR and PLS models. These models were used after their validation for the prediction of the concentration of DOM and CINN in their mixtures. The proposed procedures were successfully applied for the simultaneous determination of both drugs in laboratory prepared mixtures and in commercial tablet preparations. The validity of the proposed methods was assessed by applying the standard addition technique where the percentage recovery of the added standard was found to be 99.98+/-0.297 and 99.84+/-0.700 for DOM and CINN, respectively, using the derivative spectrophotometric method and 100.29+/-0.398 and 100.11+/-0.363 for DOM and CINN, respectively, using the PLS and PCR methods.The proposed procedures are rapid, simple, require no preliminary separation steps and can be used for routine analysis of both drugs in quality control laboratories.     

Simultaneous determination of methylxanthines in coffees and teas by UV-Vis spectrophotometry and partial least squares

This work describes a method to simultaneously determine caffeine (CF) and theobromine (TB) in coffee and tea samples using partial least squares (PLS-1). Sample preparation was required to eliminate strong interfering components. High-performance liquid chromatography (HPLC)-found concentrations of caffeine and theobromine (theophylline was not found in any analyzed sample) were used to construct universal calibration matrixes for coffee and tea. Due to the low levels of theobromine when compared to caffeine (up to 1000:1), theobromine addition standard was required to dramatically improve method performance. The method developed did not show statistically significant differences with an HPLC standard technique.     

Simultaneous determination of potassium guaiacolsulfonate, guaifenesin, diphenhydramine HCl and carbetapentane citrate in syrups by using HPLC-DAD coupled with partial least squares multivariate calibration

A simple and rapid analytical procedure was proposed for the determination of chromatographic peaks by means of partial least squares multivariate calibration (PLS) of high-performance liquid chromatography with diode array detection (HPLC-DAD). The method is exemplified with analysis of quaternary mixtures of potassium guaiacolsulfonate (PG), guaifenesin (GU), diphenhydramine HCI (DP) and carbetapentane citrate (CP) in syrup preparations. In this method, the area does not need to be directly measured and predictions are more accurate. Though the chromatographic and spectral peaks of the analytes were heavily overlapped and interferents coeluted with the compounds studied, good recoveries of analytes could be obtained with HPLC-DAD coupled with PLS calibration. This method was tested by analyzing the synthetic mixture of PG, GU, DP and CP. As a comparison method, a classsical HPLC method was used. The proposed methods were applied to syrups samples containing four drugs and the obtained results were statistically compared with each other. Finally, the main advantage of HPLC-PLS method over the classical HPLC method tried to emphasized as the using of simple mobile phase, shorter analysis time and no use of internal standard and gradient elution.     

Simultaneous kinetic-spectrophotometric determination of levodopa and benserazide by bi- and three-way partial least squares calibration

A procedure for the simultaneous kinetic-spectrophotometric determination of levodopa (I) and benserazide (II), from their oxidation reaction with KIO(4) in an acidic medium, is described. Both species instantly oxidize, giving rise to compounds which present maximum values of absorbance close to 400 nm. In the presence of an excess of the oxidizing agent, the levodopa derivative evolves to form the corresponding aminochrome (lambda(m)=480 nm), while the benserazide derivative decomposes to yield colorless compounds. The appearance of new compounds, with absorption bands in the region of 500-700 nm, is additionally seen upon adding the oxidizing agent to a mixture of I and II. These compounds also evolve decomposing and forming colorless products. In spite of the complexity of the system studied, the calibration by bi-linear partial least squares (PLS) as well as by three-way partial least squares (nPLS) permit the quantification of both analytes with a precision on the order of 0.7% for levodopa and of 1.5% for benserazide. nPLS also allows for the qualitative interpretation of the phenomena which occur. The proposed method is applied to the quantification of I and II in the commercial, pharmaceutical preparation Madopar, using high performance liquid chromatography (HPLC) as the analytical reference technique.     

Simultaneous fluorometric determination of nalidixic acid and 7-hydroxymethylnalidixic acid by partial least squares calibration

The resolution of binary mixtures of nalidixic acid (NA) and 7-hydroxymethylnalidixic acid (OH-NA) has been accomplished by partial least squares (PLS) and principal component regression (PCR) multivariate calibration. The method of determination is based on the fluorescence emission of these compounds in the presence of gamma-cyclodextrin (gamma-CD). The formation of the inclusion compounds gives rise to an increase of the fluorescence emission compared to aqueous solution. The total luminescence information of the compounds has been used to optimize the spectral data set to perform the calibration. A comparison between the predictive ability of three multivariate calibration methods, PLS-1, PLS-2 and PCR, on three spectral data sets, excitation, emission and synchronous spectra has been performed. The PLS-1 method, applied to the emission spectra, has been selected as optimum. The proposed method has been applied to the simultaneous determination of NA and OH-NA in urine. Recovery values from urine samples containing (NA) and (OH-NA) range from 91 to 103% (mean 97%), and from 92 to 105% (mean 99%), respectively.     

Simultaneous determination of quinoline yellow and brilliant blue FCF in cosmetics by solid-phase spectrophotometry

A method for the simultaneous determination of quinoline yellow (QY) and brilliant blue FCF (BB) in mixtures by solid-phase spectrophotometry has been developed. Both colorants were isolated in Sephadex DEAE A-25 gel showing maximum absorbances at 632 nm and 415 nm for BB and QY respectively. The applicable concentration ranges were between 25.0 and 500.0 mug 1(-1) for BB and between 50.0 and 750.0 mug 1(-1) for QY. The detection limits were 6.1 and 13.4 mug (-1) for BB and QY respectively. Application of the method to real samples (colognes, after shave lotions and shampoo gels) involves a previous extraction process of the colorants before their isolation on the gel.     

Multivariate calibration by partial least squares for the quantitative phase analysis using Rietveld method

The present work used multivariate calibration by Partial Least Squares (PLS) to produce a Net Analyte Signal as a way of establishing the independent influence of each phase in the Quantitative Phase Analysis with the Rietveld method for three sources of potential error: preferred orientation, linear absorption and counting statistics. Ternary mixtures of Al₂O₃, MgO and NiO were employed and organized in three groups with different degrees of variation in the weight fractions of the three constituents. An analysis of variance indicated that the partial selectivity of the least variation group differed significantly from the other groups. As for the phases, MgO partial selectivity was significantly different. This is due to a strong correlation between the linear absorption and counting statistics in the region of the (2 0 0) reflection of the MgO phase that is strongly affected by preferred orientation and also corresponds to the strongest reflection for MgO as well as for NiO. On the whole, by using matrices of similarity, a great similarity was observed between the nominal weight fractions of the phases and the weight fractions observed by means of the Rietveld method. However, such similarity diminishes as the weight fractions of the phases of the mixture become closer to each other and, in the group of mixtures with least variation of weight fractions, the method is unable to quantify the small differences between the phases, even if these errors may be considered small relative to the weight fractions themselves. Copyright © 2008 John Wiley & Sons, Ltd.     

Simultaneous kinetic-spectrophotometric determination of sulfide and sulfite and genetic algorithim variable selection using partial least squares calibration

Simultaneous multicomponent analysis is usually carried out using multivariate calibration models, such as the partial least squares (PLS) one, that utilize the full spectrum. It has been shown by both experimental and theoretical considerations that better results can by obtained by proper selection of the spectral range to be included in calculations. A genetic algorithm (GA) is one of the most popular methods for selecting variables for PLS calibration of mixtures with almost identical spectra without loss of predictive capability. In this work, a simple and precise method for rapid and accurate simultaneous determination of sulfide and sulfite ions based on the addition reaction of these ions with new fuchsin at pH 8 and 25°C using PLS regression and GA for variable selection is proposed. The concentrations of sulfide ions varied between 0.05–2.50 and 0.15–2.00 μg/mL, respectively. A series of model solutions containing different concentrations of sulfide and sulfite were used to check the predictive ability of GA-PLS models. The root mean square error of prediction with PLS on the whole data set was 0.19 μg/mL for sulfide and 0.09 μg/mL for sulfite. After the application of GA, these values reduced to 0.04 and 0.03 μg/mL, respectively. The text was submitted by the authors in English.     

Near-infrared spectroscopy quantitative determination of Pefloxacin mesylate concentration in pharmaceuticals by using partial least squares and principal component regression multivariate calibration

Pefloxacin mesylate, a broad-spectrum antibacterial fluoroquinolone, has been widely used in clinical practice. Therefore, it is very important to detect the concentration of Pefloxacin mesylate. In this research, the near-infrared spectroscopy (NIRS) has been applied to quantitatively analyze on 108 injection samples, which was divided into a calibration set containing 89 samples and a prediction set containing 19 samples randomly. In order to get a satisfying result, partial least square (PLS) regression and principal components regression (PCR) have been utilized to establish quantitative models. Also, the process of establishing the models, parameters of the models, and prediction results were discussed in detail. In the PLS regression, the values of the coefficient of determination (R²) and root mean square error of cross-validation (RMSECV) of PLS regression are 0.9263 and 0.00119, respectively. For comparison, though applying PCR method to get the values of R² and RMSECV we obtained are 0.9685 and 0.00108, respectively. And the values of the standard error of prediction set (SEP) of PLS and PCR models are 0.001480 and 0.001140. The result of the prediction set suggests that these two quantitative analysis models have excellent generalization ability and prediction precision. However, for this PFLX injection samples, the PCR quantitative analysis model achieved more accurate results than the PLS model. The experimental results showed that NIRS together with PCR method provide rapid and accurate quantitative analysis of PFLX injection samples. Moreover, this study supplied technical support for the further analysis of other injection samples in pharmaceuticals.     

偏最小二乘-分光光度法同时测定福美锌和代森锰农药残留量

利用紫外可见分光光度法研究了农药福美锌和代森锰与苯基荧光酮的相互作用,发现反应后的产物分别在波长为551和554 nm处最大有吸收,但光谱严重重叠.实验采集了450～700 nm波长范围吸光度数据,并对该数据进行一阶求导后用偏最小二乘法处理,据此建立了偏最小二乘-分光光度法同时测定福美锌和代森锰两种农药的新方法.福美锌和代森锰的线性范围分别为0.3～6.0和0.2～3.5 μg/mL;检出限分别为0.22和0.13 μg/mL.混合样品分析无需分离,方法简单、快速.用于水果、大米和自来水等实际样品测定.     

Simultaneous spectrophotometric determination of tartrazine, patent blue V, and indigo carmine in commercial products by partial least squares and principal component regression methods

Two multivariate calibration methods, partial least squares (PLS-1) and principal component regression (PCR) were proposed and successfully applied to the simultaneous determination of three dyes, tartrazine (T) (E-102), patent blue V (P) (E-131), and indigo carmine (I) (E-132) in mixtures by ultraviolet-visible absorption spectrophotometry. Calibration models were evaluated by internal validation (prediction of dyes concentration in its own designed training set of calibration), by cross-validation (obtaining statistical parameters that show the efficiency for a calibration fit model), and by external validation over 19 synthetic mixtures of the three dyes in different ratios containing 2.4-17.6 mg l(-1) of T, 1.6-5.6 mg l(-1) of P, and 3.2-17.5 mg/l(-1) of I, with recoveries between 93.5 and 103.1% and over three commercial products, in which the proposed calibration models were satisfactorily applied without separation step. Repeatability and reproducibility studies (with the Students's and F tests) were achieved over two series of nine standards for each dye, showing no significant differences at 95% confidence level.