Calibration transfer in chemiluminescence analysis Application to chromium determination by luminolhydrogen peroxide reaction

Direct standardization (DS) and piecewise direct standardization (PDS) methods are applied to multivariate standardization of chemiluminescence signals using PLS model as the calibration model. The linear concentration interval of the chemiluminescence determination was determined. This interval was located using univariate robust calibration by least median of squares (LMS) method. The linear calibration model was corroborated by conventional least-squares method. The standardization subset and window size were optimized by means of the prediction residual error sum of squares. Several instrumental sources of variability have been studied: the detection cell, instrument, batch versus flow injection (FI) modes, time and their possible combinations. This study shows the calibration transfer can be employed successfully. The proposed strategy was used in the chemiluminescence determination of Cr(III), Cr(VI) and total Cr in water samples by means of a calibration transfer. The obtained results are in agreement with reference method values and known spiked amounts, and are independent of the standardization factors.