High-pass and band-pass digital filtering with peak to trough measurement applied to quantitative ultraviolet spectrometry

Abstract

High-pass and band-pass digital filters are used to remove broad interfering bands from digitised ultraviolet spectra. Two algorithms, the binomial filter and the alternating binomial filter, are needed to access the full frequency spectrum. The methods are compared with derivative spectrometry carried out by the Savitzky-Golay method for a pharmaceutical problem (the assay of pseudoephedrine in the presence of triprolidine). Band-pass filtering has significantly better precision. It may be calibrated with stored standard data to reduce the analysis time without loss of precision.

The flexibility of digital filtering should also have advantages over derivative measurements in other analytical applications.