Application of Mid- and Near-Infrared Spectroscopy for the Control and Chemical Evaluation of Brine Solutions and Tradit
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Application of Mid- and Near-Infrared Spectroscopy for the Control and Chemical Evaluation of Brine Solutions and Traditional Sea Salts Andrea C. Galvis-Sánchez & Inês C. Santos & Raquel B. R. Mesquita & João A. Lopes & António O. S. S. Rangel & Ivonne Delgadillo
Received: 31 March 2012 / Accepted: 5 June 2012 / Published online: 16 June 2012 # Springer Science+Business Media, LLC 2012
Abstract Mid- and near-infrared spectroscopy methodologies were explored for the analysis of brine solutions and traditional sea salt samples. Brine solutions from different salt pans, corresponding to different stages of sodium chloride crystallisation, were collected. A total of 61 dried and non-dried traditional sea salts were also analysed. Partial least squares regression with leave-one-out cross-validation strategy was applied for the calibration of inorganic constituents Ca2+, Mg2+ and K+, alkalinity as HCO3−, SO42−, NO2− and NO3− and phosphate in brine solutions. Promising results were obtained with the near-infrared (NIR) methodology for brine solutions with coefficients of determination R2 >0.90 for Mg+2, K+, HCO3− and SO42−. Using mid-infrared, the A. C. Galvis-Sánchez : I. C. Santos : R. B. R. Mesquita : A. O. S. S. Rangel CBQF/Escola Superior de Biotecnologia, Universidade Católica Portuguesa, R. Dr. António Bernardino de Almeida, 4200-072 Porto, Portugal A. C. Galvis-Sánchez : I. Delgadillo (*) Departamento de Química, Campus Universitário de Santiago, QOPNA, Universidade de Aveiro, 3810-193 Aveiro, Portugal e-mail: [email protected] R. B. R. Mesquita Laboratório de Hidrobiologia, Instituto de Ciências Biomédicas de Abel Salazar (ICBAS) e Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR), Universidade do Porto, 4099-003 Porto, Portugal J. A. Lopes REQUIMTE, Laboratório de Química Aplicada, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
calibration for H2PO4− was R2 00.85. In relation to the sea salt samples, the strategy adopted was the re-sampling based cross-validation using different spectral pre-processing treatments. In this case, the calibrations using the two IR methodologies fell bellow acceptable levels for the techniques; however, by comparing the R2 coefficient, the results were slightly better when using the NIR spectra of dried sea samples. In general, these results open a new possibility for the IR applications and also bring an opportunity for continuing with the NIR characterization for dried sea salt samples. Keywords Sea-salt production . Quality control . Brine solutions . IR spectroscopy . Flow analysis . Inorganic ions
Introduction The increasing acceptability of ‘natural’ products by consumers is based on their compositional quality and the possible beneficial effects associated with their consumption. The recognition and valorisation of ‘natural’ products comes mainly for the way that they are produced, which sometimes can augment the price and boost consumers’ expectations about their qu
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