Detection of amino acids at conducting electroactive polymer modified electrodes using flow injection analysis. Part I. Use of macroelectrodes

Conducting electroactive polymer modified electrodes have been developed as sensors for the detection of amino acids subsequent to flow injection analysis (FIA). Four amino acids were selected as compounds to cover a range of properties: l-alanine (non-polar), l-serine (polar but uncharged), L-aspartic acid (acidic) and L-arginine (basic). It has been found that selectivity for the amino acids can be manipulated by changing the counterion incorporated into the polymer during growth. Thus characteristic patterns, constructed from the responses obtained from each of the above sensors considered, can be applied to improve selectivity of FIA. Linearity of calibration was demonstrated (99% confidence level) at the PPy/CSA sensor for aspartic acid over the concentration range 7.5 × 10−6 to 6 × 10−5 M. The sensitivity was 334 μC 1 mol−1 and the limit of detection (signal: noise=3) was 7.5 × 10−6 M (1 μg ml−1).