Development of the H-point standard additions method for analyte determinations in unknown matrix: Location of linear matrix spectral interval

Abstract

The development of the H-point standard additions method is proposed in order to obtain the unbiased analyte concentration when the matrix of the sample is completely unknown. A spectral region where the interferent behaviour can be considered linear at three wavelengths must be chosen. The method uses the analytical signal data at these three wavelengths, usually situated in the maxima region of the analyte. Two procedures are proposed in order to know and to locate this behaviour for the unknown interferent. Several binary and ternary mixtures of phenol, 4-chlorophenol and 4-chloro-3-methylphenol as representative examples have been assayed, with accurate (less than 3% relative error) and precise (less than 3% R.S.D. for n = 6) results for the analyte concentration, obtaining for the binary mixtures also the interferent one.