Elimination of the unknown irrelevant matrix absorbance by using the H-Point Standard Additions Method (HPSAM)

It is demonstrated how the H-Point Standard Additions Method (HPSAM) using DeltaA as analytical signal (from data at three previously selected wavelengths) is only related with analyte concentration when unknown irrelevant matrix absorbance is present. The method is compared with the most common previously reported methods, such as derivative spectroscopy or the compensation method. The obtained results show that the proposed HPSAM leads to the same found concentration of analyte as the other reported methods, except detection limits and standard deviation for six replicates which are lower, because of the use of absorbance data (instead of first derivative data as usual). In addition, the obtained data permit us to differentiate between linear and non-linear spectral behaviour for the interferent. The method was also applied to routine analyses using single-standard calibration.