Here, a simple and convenient method with suitable selectivity and high sensitivity for the determination of L-cysteine based on Belousov-Zhabotinskii (B-Z) oscillating chemical reaction is presented. The addition of L-cysteine to the oscillating system increased the oscillating period. This increasing in oscillating period is used as the analytical signal for determination of L-cysteine. The optimum conditions for the determination of L-cysteine were also investigated through a three-level Box-Behnken design. The analytical signal was linearly proportional to the logarithm of the L-cysteine concentration over the range of 4.0 × 10 -7 to 3.0 × 10 -5 M under optimum conditions. The detection limit was estimated 4.0 × 10 -7 M and relative standard deviation (RSD) for five measurements of 5.0 × 10 -6 M L-cysteine was 3.4٪.
