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- Development of a Turbidimetric Sequential Injection System to Monitor the Codfish Desalting ProcessPublication . Santos, Inês C.; Mesquita, Raquel B. R.; Galvis-Sánchez, Andrea C.; Delgadillo, Ivonne; Rangel, António Osmaro S. S.Salt-cured codfish represents an ancient process of preservation but requires the rehydration of the codfish with the correspondent salt removal. This work describes the development of a sequential injection system for the online turbidimetric determination of chloride during a simulated desalting process. The samples are directly aspirated to the manifold with no need for previous offline treatments; this was possible due to the use on an inline dialysis process; a quantification range from 50.0 mg/L to 20.0 g/L was established using the same manifold configuration. For monitoring the entire process, involving several chloride determinations (ca. 10), less than 3 mL of the desalting water was needed. Furthermore, the overall reagent consumption was quite low: 0.211 mg of AgNO3, 30.6 mg of HNO3, and 31.1 μg of PVA per determination. The accuracy of the system was evaluated by comparison with a potentiometric reference method. The determination rate was 28 and 31 h−1 according to the chloride concentration range. Several simulated desalting processes, under different conditions, were effectively monitored with the developed method.
- Evaluation of some of the main inorganic ions in brine solutions used for sea salt production by flow injection analysis and fourier-mid infrared spectroscopyPublication . Galvis-Sánchez, Andrea C.; Santos, Inês C.; Mesquita, Raquel B. R.; Lopes, João A.; Delgadillo, Ivonne; Rangel, António O. S. S.
- Application of mid- and near-infrared spectroscopy for the control and chemical evaluation of brine solutions and traditional sea saltsPublication . Galvis-Sánchez, Andrea C.; Santos, Inês C.; Mesquita, Raquel B. R.; Lopes, João A.; Rangel, António O. S. S.; Delgadillo, IvonneMid- 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 HCO (3) (-) , SO (4) (2-) , NO (2) (-) and NO (3) (-) and phosphate in brine solutions. Promising results were obtained with the near-infrared (NIR) methodology for brine solutions with coefficients of determination R (2) > 0.90 for Mg+2, K+, HCO (3) (-) and SO (4) (2-) . Using mid-infrared, the calibration for H2PO (4) (-) was R (2) = 0.85. 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 R (2) 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.
- Evaluation of some of the main inorganic ions in brine solutions used for sea salt production by flow injection analysis and fourier-mid infrared spectroscopyPublication . Galvis-Sánchez, Andrea C.; Santos, Inês; Mesquita, Raquel; Lopes, João; Delgadillo, Ivonne; Rangel, António O. S. S.