Application of correlation constrained multivariate curve resolution alternating least-squares methods for determination of compounds of interest in biodiesel blends using NIR and UV-visible spectroscopic data.
This study describes two applications of a variant of the multivariate curve resolution alternating least squares (MCR-ALS) method with a correlation constraint. The first application describes the use of MCR-ALS for the determination of biodiesel concentrations in biodiesel blends using near infrared (NIR) spectroscopic data. In the second application, the proposed method allowed the determination of the synthetic antioxidant N,N'-Di-sec-butyl-p-phenylenediamine (PDA) present in biodiesel mixtures from different vegetable sources using UV-visible spectroscopy. Well established multivariate regression algorithm, partial least squares (PLS), were calculated for comparison of the quantification performance in the models developed in both applications. The correlation constraint has been adapted to handle the presence of batch-to-batch matrix effects due to ageing effects, which might occur when different groups of samples were used to build a calibration model in the first application. Different data set configurations and diverse modes of application of the correlation constraint are explored and guidelines are given to cope with different type of analytical problems, such as the correction of matrix effects among biodiesel samples, where MCR-ALS outperformed PLS reducing the relative error of prediction RE (%) from 9.82% to 4.85% in the first application, or the determination of minor compound with overlapped weak spectroscopic signals, where MCR-ALS gave higher (RE (%)=3.16%) for prediction of PDA compared to PLS (RE (%)=1.99%), but with the advantage of recovering the related pure spectral profile of analytes and interferences. The obtained results show the potential of the MCR-ALS method with correlation constraint to be adapted to diverse data set configurations and analytical problems related to the determination of biodiesel mixtures and added compounds therein.
Grupo de Pesquisa em Quimiometria Aplicada, Instituto de Química, Universidade Federal do Rio Grande do Norte, Av. Senador Salgado Filho 3000, Natal, CEP 59078-970, Brazil; Chemometrics Group, Department of Analytical Chemistry, Universitat de Barcelona, Diagonal 645, Barcelona 08028, Spain.
Rodrigo Rocha
RR
de Oliveira
Grupo de Pesquisa em Quimiometria Aplicada, Instituto de Química, Universidade Federal do Rio Grande do Norte, Av. Senador Salgado Filho 3000, Natal, CEP 59078-970, Brazil.
Kássio Michell Gomes
KM
de Lima
Institute of Environmental Assessment and Water Studies, IDAEA-CSIC, Jordi Girona 18-26, Barcelona 08034, Spain.
Romà
R
Tauler
Chemometrics Group, Department of Analytical Chemistry, Universitat de Barcelona, Diagonal 645, Barcelona 08028, Spain. Electronic address: anna.dejuan@ub.edu.
Anna
A
de Juan
D000975:Antioxidants / Q000737:chemistry*; D056804:Biofuels; D002138:Calibration; D003627:Data Interpretation, Statistical; D003959:Diamines / Q000737:chemistry; D016018:Least-Squares Analysis; D015233:Models, Statistical; D015999:Multivariate Analysis; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet; D019265:Spectroscopy, Near-Infrared
D000975:Antioxidants; D056804:Biofuels; D003959:Diamines
Biodiesel analysis; Correlation constraint; Multivariate calibration; Multivariate curve resolution alternating least-squares; Near infrared spectroscopy; Sample matrix effect; Visible spectroscopy