DIGITAL FILTERING IN STRIPPING ANALYSIS

Stripping voltammetry has been shown to be an extremely valuable techn ique for the trace analysis of both organic and inorganic species and capable of very low limits of detection (LODs). In practice, the LOD i n stripping voltammetry is dictated by the magnitude of noise present in the actual measurement; this is so because, at the limit of very lo w concentrations, the amplitude of the noise may be comparable to, or even greater than, the magnitude of the stripping peak current, this s ituation resulting in low signal-to-noise (S/N) ratios. In this work, an attempt to tackle the problem of noise in some applications of stri pping voltammetry in flowing solutions is reported. The proposed schem e is based on the implementation of digital filtering that makes use o f a variety of filtering techniques. Both infinite impulse response fi lters (IIRFs) and finite impulse response filters (FIRFs) were utilise d and assessed. The programming task was implemented in a commercially available, novel, icon-based language that is more operator-friendly than most text-based traditional alternatives. It was found that digit al filtering provides a powerful and accessible tool for discriminatin g against noise even in cases where the S/N ratios are very unfavourab le. The relevant parameters, involving the choice of the type of filte r, cutoff frequencies, leakage effects and comparison of various filte ring windows, are discussed.