Amino acid determination using screen-printed electrochemical sensors

The use of a screen-printed electrochemical sensor (SPES) strip, consisting of a two-electrode system (a carbon working electrode and Ag/AgCl reference electrode), for amino acid determination is reported. The behaviour of the SPES toward cysteine and tyrosine is investigated using linear sweep and hydrodynamic voltammetries. The SPES operate at a lower oxidation potential (vs. Ag/AgCl) compared with traditional carbon and platinum electrodes, in a buffer solution ( pH 7) prepared using 0.1 M phosphates and 0.1M KCl. The linear response lies between 5 (*) 10(-5) M and 5 (*) 10(-4) M for both amino acids while the sensitivity is 2.95 +/- 0.03 mu A mM(-1) for cysteine and 8.00 +/- 0.01 mu A mM(-1) for tyrosine; the correlation coefficient is higher than 0.9980. The sensors were applied to the analysis of some commercial pharmaceutical samples, and the results suggested that the devices hold promise in this application area.