Application of multivariate methods in the monitoring of marine environment: simultaneous determination of bromide, bicarbonate, nitrate and sulphide in seawater by ultraviolet spectroscopy
In this paper we present a new ultraviolet (UV) spectroscopic method for the simultaneous and reagentless determination of bromide, bicarbonate, nitrate and sulphide ions in artificial seawater solutions, applicable to the monitoring of the marine environment. We collected the UV spectra of artificial seawater samples with salinity between 8 and 45 psu, having known concentrations of these anions. As their UV spectra result strongly overlapped, the anion concentrations were determined using the chemometric methods such as Principal Component Regression (PCR), Partial Least Squares Regression (PLS) and Multivariate Curve Resolution methods based on Independent Component Analysis (ICA) for the instrumental calibration. These chemometric tools, which are the novelty of the proposed method, allow to save time and cost of analysis. The analytical accuracy attainable by PCR, PLS and ICA based methods were compared and critically discussed, showing the lowest analytical accuracy of PCR with respect to PLS and ICA based methods.
Keywords: marine monitoring, seawater anions, ultraviolet spectroscopy, principal component regression, independent component analysis, partial least squares regression, multivariate curve resolution, pollution monitoring, bromide, bicarbonate, nitrate, sulphide, water pollution