Adsorption of Three Commercial Dyes onto Chitosan Beads Using Spectrophotometric Determination and a Multivariate Calibration Method

Affiliation(s)

Advanced Environmental Research Laboratories, West University of Timisoara, Timisoara, Romania.

Faculty of Mathematics and Computer Science, West University of Timisoara, Timisoara, Romania.

Advanced Environmental Research Laboratories, West University of Timisoara, Timisoara, Romania.

Faculty of Mathematics and Computer Science, West University of Timisoara, Timisoara, Romania.

ABSTRACT

A simple and rapid analytical method for the simultaneous quantification of three commercial azo dyes—Tartrazine (TAR), Congo Red (CR), and Amido Black (AB) in water is presented. The simultaneous assessment of the individual concentration of an organic dye in mixtures using a spectrophotometric method is a difficult procedure in analytical chemistry, due to spectral overlapping. This drawback can be overcome if a multivariate calibration method such as Partial Least Squares Regression (PLSR) is used. This study presents a calibration model based on absorption spectra in the 300 - 650 nm range for a set of 20 different mixtures of dyes, followed by the prediction of the concentrations of dyes in 6 validation mixtures, randomly selected, using the PLSR method. Estimated limits of detection (LOD) were 0.106, 0.047 and 0.079 mg/L for TAR, CR, and AB, respectively, and limits of quantification (LOQ) were 0.355, 0.157 and 0.265 mg/L for TAR, CR, and AB, respectively. Quantitative determination of the three azo dyes was performed following optimized adsorption experiments onto chitosan beads of mixtures of TAR, CR and AB. Adsorption isotherm and kinetic studies were carried out, proving that the proposed PLSR method is rapid, accurate and reliable.

Cite this paper

M. Mincea, V. Patrulea, A. Negrulescu, R. Szabo and V. Ostafe, "Adsorption of Three Commercial Dyes onto Chitosan Beads Using Spectrophotometric Determination and a Multivariate Calibration Method,"*Journal of Water Resource and Protection*, Vol. 5 No. 4, 2013, pp. 446-457. doi: 10.4236/jwarp.2013.54044.

M. Mincea, V. Patrulea, A. Negrulescu, R. Szabo and V. Ostafe, "Adsorption of Three Commercial Dyes onto Chitosan Beads Using Spectrophotometric Determination and a Multivariate Calibration Method,"

References

[1] C. K. Yoo, Y. H. Bang, I.-B. Lee, P. A. Vanrolleghem and C. Rosén, “Application of Fuzzy Partial Least Squares (FPLS) Modeling Nonlinear Biological Processes,” Korean Journal of Chemical Engineering, Vol. 21, No. 6, 2004, pp. 1087-1097. doi:10.1007/BF02719479

[2] R. Konduru and T. Viraraghavan, “Dye Removal Using Low Cost Adsorbents,” Water Science and Technology, Vol. 36, No. 2-3, 1997, pp. 189-196.

[3] E. Dinc, A. H. Aktas, D. Baleanu and O. üstündag, “Simultaneous Determination of Tartrazine and Allura Red in Commercial Preparation by Chemometric HPLC Method,” Journal of Food and Drug Analysis, Vol. 14, No. 3, 2006, pp. 284-291.

[4] M. K. Purkait, A. Maiti, S. DasGupta and S. De, “Removal of Congo Red Using Activated Carbon and Its Regeneration,” Journal of Hazardous Materials, Vol. 145, No. 1, 2007, pp. 287-295. doi:10.1016/j.jhazmat.2006.11.021

[5] F. A. Pavan, S. L. P. Dias, E. C. Lima and E. V. Benvenutti, “Removal of Congo Red from Aqueous Solution by Anilinepropylsilica Xerogel,” Dyes and Pigments, Vol. 76, No. 1, 2008, pp. 64-69. doi:10.1016/j.dyepig.2006.08.027

[6] A. Sayal, V. K. Bulasaram and S. Barman, “A Study on Synthesis of Zeolite and Removal of Amido Black Dye by Adsorption with Zeolite,” Chemical and Process Engineering Research, Vol. 2, 2012, pp. 54-64.

[7] S. D. Lambert, N. J. D. Graham, C. J. Sollars and G. D. Fowler, “Evaluation of Inorganic Adsorbents for the Removal of Problematic Textile Dyes and Pesticides,” Water Science and Technology, Vol. 36, No. 2-3, 1997, pp. 173-180. doi:10.1016/S0273-1223(97)00385-5

[8] T. K. Saha, N. C. Bhoumik, S. Karmaker, M. G. Ahmed, H. Ichikawa and Y. Fukumori, “Adsorption of Methyl Orange onto Chitosan from Aqueous Solution,” Journal of Water Resource and Protection, Vol. 2, No. 10, 2010, pp. 898-906. doi:10.4236/jwarp.2010.210107

[9] C. O’Neill, F. Hawkes, D. Hawkes, N. Lourenco, H. Pin- heiro and W. Delée, “Colour in Textile Effluents-Sources, Measurement, Discharge Consents and Simulation: A Review,” Journal of Chemical Technology and Biotechnology, Vol. 74, No. 11, 1999, pp. 1009-1018.

[10] S. Sahin, C. Demir and S. Gücer, “Simultaneous UV-vis Spectrophotometric Determination of Disperse Dyes in Textile Wastewater by Partial Least Squares and Principal Component Regression,” Dyes and Pigments, Vol. 73, No. 3, 2006, pp. 368-376. doi:10.1016/j.dyepig.2006.01.045

[11] P. Peralta-Zamora, A. Kunz, N. Nagata and R. J. Poppi, “Spectrophotometric Determination of Organic Dye Mixtures by Using Multivariate Calibration,” Talanta, Vol. 47, No. 1, 1998, pp. 77-84. doi:10.1016/S0039-9140(98)00073-3

[12] O. Doka, D. Bicanic, Z. Ajtony and R. Koehorst, “Determination of Sunset Yellow in Multi-Vitamin Tablets by Photoacoustic Spectroscopy and a Comparison with Alternative Methods,” Food Additives and Contaminants, Vol. 22, No. 6, 2005, pp. 507-507.

[13] S. AltinOz and S. Toptan, “Determination of Tartrazine and Ponceau-4R in Various Food Samples by Vierordt’s Method and Ratio Spectra First-Order Derivative UV Spectrophotometry,” Journal of Food Composition and Analysis, Vol. 15, No. 6, 2002, pp. 667-683. doi:10.1006/jfca.2002.1072

[14] J. J. Nevado, C. G. Cabanillas and A. M. Salcedo, “Simultaneous Spectrophotometric Determination of Three Food Dyes by Using the First Derivative of Ratio Spectra,” Talanta, Vol. 42, 1995, pp. 2043-2045. doi:10.1016/0039-9140(95)01695-3

[15] D. M. Haaland and E. V. Thomas, “Partial Least-Squares Methods for Spectral Analyses. 1. Relation to Other Quantitative Calibration Methods and the Extraction of Qualitative Information,” Analytical Chemistry, Vol. 60, No. 11, 1998, pp. 1193-1202. doi:10.1021/ac00162a020

[16] J. L. Lopez-de-Alba, L. Lopez-Martinez, V. Cerdá and L. M. De-Leon-Rodriguez, “Simultaneous Determination of Tartrazine, Sunset Yellow and Allura Red in Commercial Soft Drinks by Multivariate Spectral Analysis,” Quimica Analitica, Vol. 20, No. 2, 2001, pp. 63-72.

[17] P. Geladi, “Chemometrics in Spectroscopy. Part 1. Classical Chemometrics,” Spectrochimica Acta Part B-Atomic Spectroscopy, Vol. 58, No. 5, 2003, pp. 767-782. doi:10.1016/S0584-8547(03)00037-5

[18] B. Hemmateenejad, M. A. Safarpour and A. M. Mehranpour, “Net Analyte Signal-Artificial Neural Network (NAS- ANN) Model for Efficient Nonlinear Multivariate Calibration,” Analytica Chimica Acta, Vol. 535, No. 1, 2005, pp. 275-285.

[19] F. Bosch-Reig and P. Campins-Falco, “H-Point Standard Addition Method Part 1. Fundamentals and Application to Analytical Spectroscopy,” Analyst, Vol. 113, 1988, pp. 1011-1016.

[20] M. Perez-Urquiza and J. L. Beltran, “Determination of Dyes in Foodstuffs by Capillary Zone Electrophoresis,” Journal of Chromatography A, Vol. 898, No. 2, 2000, pp. 271-275. doi:10.1016/S0021-9673(00)00841-4

[21] P. L. Lopez-de-Alba, L. Lopez-Martinez and L. M. De-Leon-Rodriguez, “Simultaneous Determination of Synthetic Dyes Tartrazine, Allura Red and Sunset Yellow by Differential Pulse Polarography and Partial Least Squares. A Multivariate Calibration Method,” Electroanalysis, Vol. 14, No. 3, 2002, pp. 197-205. doi:10.1002/1521-4109(200202)14:3<197::AID-ELAN197>3.0.CO;2-N

[22] S. Y. Al-Degs, H. A. El-Sheikh, M. A. Al-Ghouti and M. S. Sunjuk, “Determination of Commercial Colorants in Different Water Bodies Using Partial Least Squares Regression (PLS): A Chemometric Study,” Jordan Journal of Chemistry, Vol. 3, No. 3, 2008, pp. 321-336.

[23] Y. Bingchao, R. Huang and Q. Lui, “Adsorption of Amido Black 10B onto Cross-Linked Chitosan,” Research Journal of Chemistry and Environment, Vol. 16, No. 3, 2012, pp. 110-115.

[24] S. Chatterjee, W. M. Min and H. W. Seung, “Adsorption of Congo Red by Chitosan Hydrogel Beads Impregnated with Carbon Nanotubes,” Bioresource Technology, Vol. 101, No. 6, 2010, pp. 1800-1806. doi:10.1016/j.biortech.2009.10.051

[25] W. S. W. Ngah, F. M. A. Noorul and A. K. M. H. Megat, “Preparation, Characterization, and Environmental Application of Crosslinked Chitosan-Coated Bentonite for Tartrazine Adsorption from Aqueous Solutions,” Water Air and Soil Pollution, Vol. 206, No. 1-4, 2010, pp. 225-236.

[26] I. Langmuir, “The Constitution and Fundamental Properties of Solids and Liquids,” Journal of the American Chemical Society, Vol. 38, No. 11, 1916, pp. 2221-2295. doi:10.1016/S0016-0032(17)90088-2

[27] K. Vijayaraghavan, T. V. N. Padmesh, K. Palanivelu and M. Velan, “Biosorption of Nickel (II) Ions onto Sargassum Wightii: Application of Two-Parameter and Three Parameter Isotherm Models,” Journal of Hazardous Materials, Vol. B133, No. 1-3, 2006, pp. 304-308.

[28] S. Kundu and A. K. Gupta, “Arsenic Adsorption onto Iron Oxide-Coated Cement (IOCC): Regression Analysis of Equilibrium Data with Several Isotherm Models and Their Optimization,” Chemical Engineering Journal, Vol. 122, 2006, pp. 93-106.

[29] H. M. F. Freundlich, “Over the Adsorption in Solution,” Journal of Physical Chemistry A, Vol. 57, 1906, pp. 385-471.

[30] A. W. Adamson and A. P. Gast, “Physical Chemistry of Surfaces,” 6th Edition, Wiley-Interscience, New York, 1997.

[31] M. I. Temkin, “Adsorption Equilibrium and the Kinetics of Processes on Nonhomogeneous Surfaces and in the Interaction between Adsorbed Molecules,” Zhurnal Fiziche- skoi Khimii, Vol. 15, 1941, pp. 296-332.

[32] S. Y. Elovich and O. G. Larinov, “Theory of Adsorption from Solutions of Non Electrolytes on Solid (I) Equation Adsorption from Solutions and the Analysis of Its Simplest Form, (II) Verification of the Equation of Adsorption Isotherm from Solutions,” Izvestiya Akademii Nauk. SSSR, Otdelenie Khimicheskikh Nauk, Vol. 2, 1962, pp. 209-216.

[33] E. Bulut, M. Ozacar and I. A. Sengil, “Adsorption of Malachite Green onto Bentonite: Equilibrium and Kinetic Studies and Process Design,” Microporous Mesoporous Materials, Vol, 115, No. 3, 2008, pp. 234-246. doi:10.1016/j.micromeso.2008.01.039

[34] I. S. McLintock, “The Elovich Equation in Chemisorption Kinetics,” Nature, Vol. 216, No. 5121, 1967, pp. 1204-1205. doi:10.1038/2161204a0

[35] Y. S. Ho and G. Mckay, “The Sorption of Lead (II) Ions on Peat,” Water Research, Vol. 33, No. 2, 1999, pp. 578-584. doi:10.1016/S0043-1354(98)00207-3

[36] M. S. Chiou and H. Y. Li, “Adsorption Behavior of Reactive Dye in Aqueous Solution on Chemical Cross-Linked Chitosan Beads,” Chemosphere, Vol. 50, No. 8, 2003, pp. 1095-1105. doi:10.1016/S0045-6535(02)00636-7

[37] B. Hemmateenejad, A. Abbspour, H. Maghami, R. Miri and M. Panjehshahin, “Partial Least Squares-Based Multivariate Spectral Calibration Method for Simultaneous Determination of Beta-Carboline Derivatives,” Analytica Chimica Acta, Vol. 575, No. 2, 2006, pp. 290-299.

[38] A. Abbaspour and M. Najafi, “Simultaneous Determination of Sb(III) and Sb(V) by Partial Least Squares Regression,” Talanta, Vol. 60, No. 5, 2003, pp. 1079-1084.

[39] A. M. C. Davies and T. Fearn, “Back to Basics: Calibration Statistics,” Spectroscopy Europe, Vol. 18, No. 2, 2006, pp. 31-32.

[40] P. Lopez-de-Alba, L. Lopez-Martinez, V. Cerdáa and J. Amador-Hernandez, “Simultaneous Determination and Classification of Riboflavin, Thiamine, Nicotinamide and Pyridoxine in Pharmaceutical Formulations, by UV-Visible Spectrophotometry and Multivariate Analysis,” Journal of the Brazilian Chemical Society, Vol. 17, No. 4, 2006, pp. 715-722. doi:10.1590/S0103-50532006000400012

[1] C. K. Yoo, Y. H. Bang, I.-B. Lee, P. A. Vanrolleghem and C. Rosén, “Application of Fuzzy Partial Least Squares (FPLS) Modeling Nonlinear Biological Processes,” Korean Journal of Chemical Engineering, Vol. 21, No. 6, 2004, pp. 1087-1097. doi:10.1007/BF02719479

[2] R. Konduru and T. Viraraghavan, “Dye Removal Using Low Cost Adsorbents,” Water Science and Technology, Vol. 36, No. 2-3, 1997, pp. 189-196.

[3] E. Dinc, A. H. Aktas, D. Baleanu and O. üstündag, “Simultaneous Determination of Tartrazine and Allura Red in Commercial Preparation by Chemometric HPLC Method,” Journal of Food and Drug Analysis, Vol. 14, No. 3, 2006, pp. 284-291.

[4] M. K. Purkait, A. Maiti, S. DasGupta and S. De, “Removal of Congo Red Using Activated Carbon and Its Regeneration,” Journal of Hazardous Materials, Vol. 145, No. 1, 2007, pp. 287-295. doi:10.1016/j.jhazmat.2006.11.021

[5] F. A. Pavan, S. L. P. Dias, E. C. Lima and E. V. Benvenutti, “Removal of Congo Red from Aqueous Solution by Anilinepropylsilica Xerogel,” Dyes and Pigments, Vol. 76, No. 1, 2008, pp. 64-69. doi:10.1016/j.dyepig.2006.08.027

[6] A. Sayal, V. K. Bulasaram and S. Barman, “A Study on Synthesis of Zeolite and Removal of Amido Black Dye by Adsorption with Zeolite,” Chemical and Process Engineering Research, Vol. 2, 2012, pp. 54-64.

[7] S. D. Lambert, N. J. D. Graham, C. J. Sollars and G. D. Fowler, “Evaluation of Inorganic Adsorbents for the Removal of Problematic Textile Dyes and Pesticides,” Water Science and Technology, Vol. 36, No. 2-3, 1997, pp. 173-180. doi:10.1016/S0273-1223(97)00385-5

[8] T. K. Saha, N. C. Bhoumik, S. Karmaker, M. G. Ahmed, H. Ichikawa and Y. Fukumori, “Adsorption of Methyl Orange onto Chitosan from Aqueous Solution,” Journal of Water Resource and Protection, Vol. 2, No. 10, 2010, pp. 898-906. doi:10.4236/jwarp.2010.210107

[9] C. O’Neill, F. Hawkes, D. Hawkes, N. Lourenco, H. Pin- heiro and W. Delée, “Colour in Textile Effluents-Sources, Measurement, Discharge Consents and Simulation: A Review,” Journal of Chemical Technology and Biotechnology, Vol. 74, No. 11, 1999, pp. 1009-1018.

[10] S. Sahin, C. Demir and S. Gücer, “Simultaneous UV-vis Spectrophotometric Determination of Disperse Dyes in Textile Wastewater by Partial Least Squares and Principal Component Regression,” Dyes and Pigments, Vol. 73, No. 3, 2006, pp. 368-376. doi:10.1016/j.dyepig.2006.01.045

[11] P. Peralta-Zamora, A. Kunz, N. Nagata and R. J. Poppi, “Spectrophotometric Determination of Organic Dye Mixtures by Using Multivariate Calibration,” Talanta, Vol. 47, No. 1, 1998, pp. 77-84. doi:10.1016/S0039-9140(98)00073-3

[12] O. Doka, D. Bicanic, Z. Ajtony and R. Koehorst, “Determination of Sunset Yellow in Multi-Vitamin Tablets by Photoacoustic Spectroscopy and a Comparison with Alternative Methods,” Food Additives and Contaminants, Vol. 22, No. 6, 2005, pp. 507-507.

[13] S. AltinOz and S. Toptan, “Determination of Tartrazine and Ponceau-4R in Various Food Samples by Vierordt’s Method and Ratio Spectra First-Order Derivative UV Spectrophotometry,” Journal of Food Composition and Analysis, Vol. 15, No. 6, 2002, pp. 667-683. doi:10.1006/jfca.2002.1072

[14] J. J. Nevado, C. G. Cabanillas and A. M. Salcedo, “Simultaneous Spectrophotometric Determination of Three Food Dyes by Using the First Derivative of Ratio Spectra,” Talanta, Vol. 42, 1995, pp. 2043-2045. doi:10.1016/0039-9140(95)01695-3

[15] D. M. Haaland and E. V. Thomas, “Partial Least-Squares Methods for Spectral Analyses. 1. Relation to Other Quantitative Calibration Methods and the Extraction of Qualitative Information,” Analytical Chemistry, Vol. 60, No. 11, 1998, pp. 1193-1202. doi:10.1021/ac00162a020

[16] J. L. Lopez-de-Alba, L. Lopez-Martinez, V. Cerdá and L. M. De-Leon-Rodriguez, “Simultaneous Determination of Tartrazine, Sunset Yellow and Allura Red in Commercial Soft Drinks by Multivariate Spectral Analysis,” Quimica Analitica, Vol. 20, No. 2, 2001, pp. 63-72.

[17] P. Geladi, “Chemometrics in Spectroscopy. Part 1. Classical Chemometrics,” Spectrochimica Acta Part B-Atomic Spectroscopy, Vol. 58, No. 5, 2003, pp. 767-782. doi:10.1016/S0584-8547(03)00037-5

[18] B. Hemmateenejad, M. A. Safarpour and A. M. Mehranpour, “Net Analyte Signal-Artificial Neural Network (NAS- ANN) Model for Efficient Nonlinear Multivariate Calibration,” Analytica Chimica Acta, Vol. 535, No. 1, 2005, pp. 275-285.

[19] F. Bosch-Reig and P. Campins-Falco, “H-Point Standard Addition Method Part 1. Fundamentals and Application to Analytical Spectroscopy,” Analyst, Vol. 113, 1988, pp. 1011-1016.

[20] M. Perez-Urquiza and J. L. Beltran, “Determination of Dyes in Foodstuffs by Capillary Zone Electrophoresis,” Journal of Chromatography A, Vol. 898, No. 2, 2000, pp. 271-275. doi:10.1016/S0021-9673(00)00841-4

[21] P. L. Lopez-de-Alba, L. Lopez-Martinez and L. M. De-Leon-Rodriguez, “Simultaneous Determination of Synthetic Dyes Tartrazine, Allura Red and Sunset Yellow by Differential Pulse Polarography and Partial Least Squares. A Multivariate Calibration Method,” Electroanalysis, Vol. 14, No. 3, 2002, pp. 197-205. doi:10.1002/1521-4109(200202)14:3<197::AID-ELAN197>3.0.CO;2-N

[22] S. Y. Al-Degs, H. A. El-Sheikh, M. A. Al-Ghouti and M. S. Sunjuk, “Determination of Commercial Colorants in Different Water Bodies Using Partial Least Squares Regression (PLS): A Chemometric Study,” Jordan Journal of Chemistry, Vol. 3, No. 3, 2008, pp. 321-336.

[23] Y. Bingchao, R. Huang and Q. Lui, “Adsorption of Amido Black 10B onto Cross-Linked Chitosan,” Research Journal of Chemistry and Environment, Vol. 16, No. 3, 2012, pp. 110-115.

[24] S. Chatterjee, W. M. Min and H. W. Seung, “Adsorption of Congo Red by Chitosan Hydrogel Beads Impregnated with Carbon Nanotubes,” Bioresource Technology, Vol. 101, No. 6, 2010, pp. 1800-1806. doi:10.1016/j.biortech.2009.10.051

[25] W. S. W. Ngah, F. M. A. Noorul and A. K. M. H. Megat, “Preparation, Characterization, and Environmental Application of Crosslinked Chitosan-Coated Bentonite for Tartrazine Adsorption from Aqueous Solutions,” Water Air and Soil Pollution, Vol. 206, No. 1-4, 2010, pp. 225-236.

[26] I. Langmuir, “The Constitution and Fundamental Properties of Solids and Liquids,” Journal of the American Chemical Society, Vol. 38, No. 11, 1916, pp. 2221-2295. doi:10.1016/S0016-0032(17)90088-2

[27] K. Vijayaraghavan, T. V. N. Padmesh, K. Palanivelu and M. Velan, “Biosorption of Nickel (II) Ions onto Sargassum Wightii: Application of Two-Parameter and Three Parameter Isotherm Models,” Journal of Hazardous Materials, Vol. B133, No. 1-3, 2006, pp. 304-308.

[28] S. Kundu and A. K. Gupta, “Arsenic Adsorption onto Iron Oxide-Coated Cement (IOCC): Regression Analysis of Equilibrium Data with Several Isotherm Models and Their Optimization,” Chemical Engineering Journal, Vol. 122, 2006, pp. 93-106.

[29] H. M. F. Freundlich, “Over the Adsorption in Solution,” Journal of Physical Chemistry A, Vol. 57, 1906, pp. 385-471.

[30] A. W. Adamson and A. P. Gast, “Physical Chemistry of Surfaces,” 6th Edition, Wiley-Interscience, New York, 1997.

[31] M. I. Temkin, “Adsorption Equilibrium and the Kinetics of Processes on Nonhomogeneous Surfaces and in the Interaction between Adsorbed Molecules,” Zhurnal Fiziche- skoi Khimii, Vol. 15, 1941, pp. 296-332.

[32] S. Y. Elovich and O. G. Larinov, “Theory of Adsorption from Solutions of Non Electrolytes on Solid (I) Equation Adsorption from Solutions and the Analysis of Its Simplest Form, (II) Verification of the Equation of Adsorption Isotherm from Solutions,” Izvestiya Akademii Nauk. SSSR, Otdelenie Khimicheskikh Nauk, Vol. 2, 1962, pp. 209-216.

[33] E. Bulut, M. Ozacar and I. A. Sengil, “Adsorption of Malachite Green onto Bentonite: Equilibrium and Kinetic Studies and Process Design,” Microporous Mesoporous Materials, Vol, 115, No. 3, 2008, pp. 234-246. doi:10.1016/j.micromeso.2008.01.039

[34] I. S. McLintock, “The Elovich Equation in Chemisorption Kinetics,” Nature, Vol. 216, No. 5121, 1967, pp. 1204-1205. doi:10.1038/2161204a0

[35] Y. S. Ho and G. Mckay, “The Sorption of Lead (II) Ions on Peat,” Water Research, Vol. 33, No. 2, 1999, pp. 578-584. doi:10.1016/S0043-1354(98)00207-3

[36] M. S. Chiou and H. Y. Li, “Adsorption Behavior of Reactive Dye in Aqueous Solution on Chemical Cross-Linked Chitosan Beads,” Chemosphere, Vol. 50, No. 8, 2003, pp. 1095-1105. doi:10.1016/S0045-6535(02)00636-7

[37] B. Hemmateenejad, A. Abbspour, H. Maghami, R. Miri and M. Panjehshahin, “Partial Least Squares-Based Multivariate Spectral Calibration Method for Simultaneous Determination of Beta-Carboline Derivatives,” Analytica Chimica Acta, Vol. 575, No. 2, 2006, pp. 290-299.

[38] A. Abbaspour and M. Najafi, “Simultaneous Determination of Sb(III) and Sb(V) by Partial Least Squares Regression,” Talanta, Vol. 60, No. 5, 2003, pp. 1079-1084.

[39] A. M. C. Davies and T. Fearn, “Back to Basics: Calibration Statistics,” Spectroscopy Europe, Vol. 18, No. 2, 2006, pp. 31-32.

[40] P. Lopez-de-Alba, L. Lopez-Martinez, V. Cerdáa and J. Amador-Hernandez, “Simultaneous Determination and Classification of Riboflavin, Thiamine, Nicotinamide and Pyridoxine in Pharmaceutical Formulations, by UV-Visible Spectrophotometry and Multivariate Analysis,” Journal of the Brazilian Chemical Society, Vol. 17, No. 4, 2006, pp. 715-722. doi:10.1590/S0103-50532006000400012