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.     

Resolution of ternary mixtures of Tartrazine, Sunset yellow and Ponceau 4R by derivative spectrophotometric ratio spectrum-zero crossing method in commercial foods

A very simple spectrophotometric method is described for resolving ternary mixtures of the food colorants Tartrazine, Sunset Yellow and Ponceau 4R by using the first derivative of the ratio spectra with measurements at zero-crossing wavelengths. Calibration graphs are linear up to 20 mg l(-1) of Tartrazine (E-102), 40 mg l(-1) of Sunset Yellow (E-110) and 32 mg l(-1) of Ponceau 4R (E-124). Standard deviations of 0.9, 0.8 and 2.4% were obtained for nine standards of 8 mg l(-1) of Tartrazine, 8 mg l(-1) of Sunset Yellow and 8 mg l(-1) of Ponceau 4R, respectively. This method was satisfactorily used for determining synthetic mixtures of these colorants in different ratios (from 1:1:1 to 1:5:5 or even higher) with recoveries in 94-105% range and it was successfully applied over three commercial products containing the three dyes and it did not require any separation step. The results were compared with those obtained by HPLC and very similar values were found by both methods.     

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     

Spectrophotometric Simultaneous Determination of Amaranth,Ponceau 4R,Allura Red and Red 2G by Partial Least Squares and Principal Component Regression Multivariate Calibration

ABSTRACT

The multivariate calibration methods, partial least square regression type 1 (PLS 1) and principal component regression (PCR), were proposed for the simultaneous spectrophotometry determination of Amaranth (E-123), Ponceau 4R (E-124), Allura red (E-129) and Red 2G (E-128) in their mixtures. The parameters of the chemometric procedures were optimized and the proposed method was validated with synthetic samples and applied to analyze these dyes in spiked samples of beverages with satisfactory results.     

Derivative spectrophotometric resolution of mixtures of the food colourants Tartrazine, Amaranth and Curcumin in a micellar medium

A study of the absorption spectra of the food colourants Tartrazine (E-102), Amaranth (E-123) and Curcumin (E-100) in various organic solvents and pH media, have been carried out. In addition, the spectral behaviour in aqueous micellar systems of anionic, cationic and non-ionic surfactants, as well as beta-cyclodextrin, was investigated. Analytical methods are proposed for the determination of the three dyes in mixtures without any prior separation step, by the application of the derivative technique to the normal absorption spectra, based on the use of cetyltrimethylammonium bromide (CTAB) in 0.1 M NaOH, over the concentration range 2-50 mug ml(-1). The methods are applied for determining the three dyes in commercial food products.     

Rapid Spectrophotometric Method for Determining Erythrosine,Amaranth and Tartrazine in Ternary Mixtures

Abstract

A very simple spectrophotometric method using measurements at zero-crossing wavelength is described for resolving ternary mixtures of the food colorants Erythrosine (E-127), Amaranth (E-123) and Tartrazine (E-102). Calibration graphs are linear up to 14 mg/L of Erythrosine and 28 mg/L for Tartrazine and Amaranth. RSD of 0.80, 0.85 and 1.84% were obtained for nine standards of 8 mg/L of Erythrosine, 8 mg/L of Tartrazine and 8 mg/L of Amaranth, respectively. Detection limits of 0.052, 0.934 and 0.123 mg/L were obtained for Erythrosine, Tartrazine and Amaranth, respectively. This method was satisfactorily used for determining synthetic mixtures of these colorants in different ratios and it was successfully applied to a commercial product containing the three dyes; no separation step is required. The results were compared with those obtained by liquid chromatography and very similar values were found by both methods.     

Rapid spectrophotometric method to resolve ternary mixtures of Tartrazine, Quinoline Yellow and Patent Blue V in commercial products

A very simple spectrophotometric method is described for resolving ternary mixtures of the food dyes Tartrazine (E-102), Quinoline Yellow (E-104) and Patent Blue V (E-131) by using the second derivative of the spectra with measurements at zero-crossing wavelengths. Calibration graphs are linear up to 20.0 mg/L of Tartrazine, up to 20.0 mg/L of Quinoline Yellow and up to 6.4 mg/L of Patent Blue V. Repeatability and reproducibility studies (with the Students’s and F tests) were achieved for two series of nine standards for each dye showing no significant differences at the 95% confidence level. Detection limits of 0.0526, 0.0164 and 0.0034 mg/L were obtained for Tartrazine, Quinoline Yellow and Patent Blue V, respectively. This method was used for determining synthetic mixtures of these colorants in different ratios and it was successfully applied to four commercial products without previous separation step. The results found in commercial products were compared with those obtained by an HPLC method and very similar values were found for both methods.     

Rapid spectrophotometric method to resolve ternary mixtures of Tartrazine, Quinoline Yellow and Patent Blue V in commercial products

A very simple spectrophotometric method is described for resolving ternary mixtures of the food dyes Tartrazine (E-102), Quinoline Yellow (E-104) and Patent Blue V (E-131) by using the second derivative of the spectra with measurements at zero-crossing wavelengths. Calibration graphs are linear up to 20.0 mg/L of Tartrazine, up to 20.0 mg/L of Quinoline Yellow and up to 6.4 mg/L of Patent Blue V. Repeatability and reproducibility studies (with the Students’s and F tests) were achieved for two series of nine standards for each dye showing no significant differences at the 95% confidence level. Detection limits of 0.0526, 0.0164 and 0.0034 mg/L were obtained for Tartrazine, Quinoline Yellow and Patent Blue V, respectively. This method was used for determining synthetic mixtures of these colorants in different ratios and it was successfully applied to four commercial products without previous separation step. The results found in commercial products were compared with those obtained by an HPLC method and very similar values were found for both methods. Received: 28 December / Revised: 26 May 1999 / Accepted: 31 May 1999     

Mathematical algorithms applied to the multi-linear regression functions for the multicomponent determination of pharmaceutical dosage form containing three-component mixtures

In the presence of closely overlapping spectra, the quantitative multiresolution of ternary mixtures of three active compounds paracetamol (PAR), caffeine (CAF) and acetylsalycilic acid (ASP) in tablets, without using pretreatment such as separation step and graphical procedure of spectra was accomplished by the multivariate spectral calibration models, tri-linear regression calibration (TLRC), multi-linear regression calibration (MLRC) and Cramer's rule solution (CRS) of three linear equation functions in the matrix form. In the first two models, TLRC and MLRC are based on the use of the linear regression functions at selected wavelength sets in the spectral region of 210-300 nm. In the case of CRS model, A1(1) (1%, 1 cm) were used to obtain three linear equation functions and this linear equation system was resolved by the Cramer's rule for the prediction of PAR, CAF and ASP in samples. In the TLRC and CRS models, the selection of the appropriate wavelength set was performed by the Kaiser's technique. The algorithms of these mathematical calibration models were briefly described. The validation of TLRC, MLRC and CRS models was carried out by analyzing various synthetic ternary mixtures and by using the standard addition technique. These three calibration approaches were applied to the analysis of the real pharmaceutical tablets containing PAR, CAF and ASP. The obtained results were statistically compared with each other by using experimental and statistical tests. In the comparison of TLRC and MLRC models to the classical approach, CRS technique, the successful assay results were observed for the quantitative multiresolution of ternary mixture of the subject active compounds.     

Spectrophotometric determination of organic dye mixtures by using multivariate calibration

The simultaneous determination of organic dye mixtures by using spectrophotometric methods is a difficult problem in analytical chemistry, due to spectral interferences. By using multivariate calibration methods such as partial least-squares regression (PLSR), it is possible to obtain a model adjusted to the concentration values of the mixtures used in the calibration stage. In this study, the calibration model is based on absorption spectra in the 350-650-nm range for a set of 16 different mixtures of reactive red 195, reactive yellow 145 and reactive orange 122 dyes, and made the determination of the dye concentrations possible in a validation set with significantly greater accuracy than the conventional univariate calibration method. By using the developed model it was possible to monitor the decolorization kinetic of one dye (reactive orange 122), when the mixture of the three dyes was previously submitted to an ozonation process.     

Simultaneous spectrophotometric determination of Fe and Ni with xylenol orange using principal component analysis and artificial neural networks in some industrial samples

Artificial neural networks (ANNs) are among the most popular techniques for nonlinear multivariate calibration in complicated mixtures using spectrophotometric data. In this study, Fe and Ni were simultaneously determined in aqueous medium with xylenol orange (XO) at pH 4.0. In this way, after reducing the number of spectral data using principal component analysis (PCA), an artificial neural network consisting of three layers of nodes was trained by applying a back-propagation learning rule. Sigmoid transfer functions were used in the hidden and output layers to facilitate nonlinear calibration. Adjustable experimental and network parameters were optimized, 30 calibration and 20 prediction samples were prepared over the concentration ranges of 0-400 mug l(-1) Fe and 0-300 mug l(-1) Ni. The resulting R.S.E. of prediction (S.E.P.) of 3.8 and 4.7% for Fe and Ni were obtained, respectively. The method has been applied to the spectrophotometric determination of Fe and Ni in synthetic samples, some Ni alloys, and some industrial waste waters.     

Simultaneous Determination of Hydrocortisone and Zn-Bacitracin by Spectrophotometric Derivative and Multivariate Methods

 Four spectrophotometric methods are described and applied to resolve binary mixtures of the corticosteroid hydrocortisone and the antibacterial polypeptide Zn-Bacitracin. The simultaneous determination of the two compounds was accomplished by means of derivative methods, which were satisfactory used to determine synthetic mixtures of these compounds in different ratios and in pharmaceutical preparations (only for hydrocortisone). Direct absorption spectra of compounds were used to optimise the spectral data set performs the calibration by PLS-1, PLS-2 and PCR algorithms. These calibration models were evaluated through internal validation (prediction of compounds in its own designed training set of calibration), cross-validation (obtaining statistical parameters that show the efficiency for a calibration fit model) and external validation over synthetic and pharmaceutical mixtures. The four described procedures do not require any separation step. Precision studies were achieved over two series of ten standards for each compound showing no significant differences at 95% confidence level in the two spectrophotometric methods. The results found in commercial products were compared with those obtained by means of MEKC method and similar values were found. Correspondence: Department of Analytical Chemistry and Food Technology, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain. e-mail: JoseMaria.Lemus@uclm.es Received January 25, 2002; accepted October 22, 2002     

Simultaneous spectrofluorimetric determination of europium, dysprosium, gadolinium and terbium using chemometric methods

A spectrofluorimetric method for the simultaneous determination of dysprosium, europium, gadolinium and terbium in ternary and quaternary mixtures by the use of pyridine-2,6-dicarboxylic acid as a chelating agent was developed. The influence of chemical variables affecting the analytical reaction was evaluated. A partial least-squares procedure and PC Quant software were used to assess data obtained from a variable number of calibration solutions and wavelengths. The ensuing method was validated by applying it to the analysis of synthetic ternary (Eu-Dy-Tb) and quaternary mixtures (Eu-Dy-Gd-Tb) over the concentration ranges 60-550 mug Eu l(-1), 30-400 mug Dy l(-1) and 30-400 mug Tb l(-1) in the former, and 20-220 mug Eu l(-1), 20-235 mug Dy l(-1), 25-230 mug Gd l(-1) and 75-230 mug Tb l(-1) in the latter. The results obtained by using the two quantitation procedures are compared. The relative errors in the determinations were less than 8% in most cases.     

Kinetic spectrophotometric determination of Ga(III)-Al(III) mixtures by stopped-flow injection analysis using principal component regression

A multivariate calibration method based on principal component regression analysis is applied to the resolution of mixtures by kinetic methodology. Gallium(III) and Al(III) were determined in mixtures on the basis of their different rate of reaction with 4-(2-pyridylazo)resorcinol in a slightly basic medium by using a stopped-flow injection procedure. Mixtures containing 1-5 mg/l. Ga(III) and 20-100 mg/l. Al(III) were successfully resolved with errors less than 10%.     

A comparative study of AgX (X = Cl(-), Br(-), I(-) and N(3)(-)) solid-phase reactors for flow-injection determination of cyanide in electroplating wastewater.

In this study, a rapid flow injection-flame atomic absorption spectrometry for cyanide detection was developed. Different AgX (where X is Cl(-), Br(-), I(-) and N(3)(-)) solid-phase reagents (SPR) were tested for indirect determination of cyanide. In a single-line FIA system, the cyanide was allowed to react with AgX SPR, which in turn changed Ag ions in AgX to silver cyanide complexes in a sodium hydroxide carrier stream. The eluent containing the analyte as silver cyanide complexes was measured by FAAS. The calibration curve was linear up to 30 mg l(-1) with a detection limit of 0.05 mg l(-1) for cyanides. The sampling rate and the relative standard deviation were <1.09% and >200 h(-1), respectively. The method was applied to the determination of cyanide in electroplating wastewater.     

Reflectance near-infrared spectroscopic method with Chemometric techniques for simultaneous determination of Chondroitin, glucosamine, and methyl sulfonyl methane

Reflectance near-IR (RNIR) spectroscopy was used for the simultaneous determination of chondroitin (CH), glucosamine (GO), and methyl sulfonyl methane (MSM) in tablets. Simple sample preparation was done by grinding, sieving, and compression of the tablets for improving RNIR spectra. Principal component regression and partial least squares (PLS-1 and PLS-2) were successfully applied to quantify the three components in the studied mixture using information included in RNIR spectra in the range of 4350-9100 cm(-1). The calibration model was developed with drug concentration ranges of 14.5-44.2% (w/w) for CH, 18.4-55.3% (w/w) for GO, and 6-18.6% (w/w) for MSM with addition of tablet excipients to the calibration set in the same ratio as in the tested tablets. The calibration models were evaluated by internal validation, cross-validation, and external validation using synthetic and pharmaceutical preparations. The proposed method was applied for analysis of six batches of the pharmaceutical product. The results of the proposed method were compared with the results of the pharmacopoeial method for the same batch of the pharmaceutical product. No significant differences between the results were found. The RNIR method is accurate and precise, and can be used for QC of pharmaceutical products.     

Flame AAS and UV-VIS determination of cobalt, nickel and palladium using the synergetic effect of 2-benzoylpyridine-2-pyridylhydrazone and thiocyanate ions

A quantitative synergetic extraction procedure for cobalt, nickel and palladium from thiocyanate aqueous solutions into methyl isobutyl ketone (MIBK), containing 2-benzoylpyridine-2-pyridylhydrazone (BPPH), was studied by flame atomic absorption spectrometry (FAAS) and molecular absorption spectrometry (UV-VIS). Using FAAS, linear calibration graphs were obtained from 0.0-0.5 mg l(-1) Co(II), 0.0-1.5 mg l(-1) Ni(II) and 0.0-2.0 mg l(-1) Pd(II). The reproducibilities were s(r,Co(II))=2.0%, s(r,Ni(II))=1.0% and s(r,Pd(II))=1.3% and the limits of detection were c(L,Co(II))=0.004 mg l(-1), c(L,Ni(II))=0.009 mg l(-1) and c(L,Pd(II))=0.012 mg l(-1). Using UV-VIS method the linear calibration graphs were 0.0-0.5 mg l(-1) for Co(II), 0.0-1.0 mg l(-1) for Ni(II) and 0.0-2.0 mg l(-1) for Pd(II). The reproducibilities were s(r,Co(II))=1.3%, s(r,Ni(II))=1.7% and s(r,Pd(II))=1.0% and the limits of detection were c(L,Co(II))=0.001 mg l(-1), c(L,Ni(II))=0.004 mg l(-1) and c(L,Pd(II))=0.002 mg l(-1). The extraction method is almost free from interferences and has been successfully applied to the determination of cobalt, nickel and palladium in dental alloys.     

Simultaneous determination of copper, cadmium and nickel by ratio derivative polarography

Ternary mixtures of metals can be resolved by using the ratio derivative polarography without the need for any pre-separation step. The method is based on the simultaneous use of the first derivative of ratios of polarograms and measurements of zero-crossing potentials. The polarogram of the mixture is obtained and the amplitudes of the current at appropriate potentials are divided by the corresponding amplitudes in the polarogram of a standard solution of one of the components, and the subsequent derivation against potential results to the first derivative of the ratio polarogram. The concentrations of the other two components are then determined from their respective calibration graphs established by measuring the ratio derivative analytical signal at the selected zero-crossing points. The method has been successfully applied for resolving ternary mixtures of copper, cadmium and nickel, which have overlapped polarograms in pH 2.87 Britton-Robinson buffer. The concentration ranges to be determined are 0.30-1.40 mg l(-1) for copper, 0.90-4.50 mg l(-1) for cadmium and 0.20-1.20 mg l(-1) for nickel, and the recoveries are 88.3-101.9% for copper, 92.2-105.4% for cadmium and 95.0-107.0% for nickel.     

Double lactonization in triarylamine-conjugated dimethyl diethynylfumarate: formation of intensely colored and luminescent quadrupolar molecules including a missing structural isomer of Pechmann dyes

Acid-induced double lactonization in triarylamine-conjugated dimethyl diethynylfumarate E-1 opens up a new synthetic route to Pechmann dyes. This one-pot reaction affords three donor-acceptor-donor quadrupolar molecules (P(55)-1, P(66)-1, and P(56)-1); P(56)-1 comprises a missing structural isomer of Pechmann dyes. They are intensely colored and brightly luminescent. An organic field-effect transistor device fabricated with P(66)-1 functions as a p-type semiconductor.     

A Voltammetric Electronic Tongue Based on Commercial Screen‐printed Electrodes for the Analysis of Aminothiols by Differential Pulse Voltammetry

A voltammetric electronic tongue has been designed as a proof of concept for the analysis of aminothiols by differential pulse voltammetry and has been tested in ternary mixtures of cysteine (Cys), homocysteine (hCys) and glutathione (GSH). It consists of three screen‐printed electrodes of carbon, carbon nanofibers and gold cured at low temperature. A preliminary calibration study carried out separately for each aminothiol confirmed that, working at an optimal pH value of 7.4, every electrode produces differentiated responses for every analyte (cross‐response). As for the tongue, it was applied to calibration and validation mixtures of Cys, hCys and GSH and provided voltammograms that, baseline‐corrected, normalized and combined in different ways were submitted to partial least squares (PLS) calibration. The calibration models produced good predictions of the concentrations of all three analytes, which suggest that the proposed voltammetric tongue improves the performance of a previous design based on linear sweep voltammetric measurements under acidic conditions.