Disturbance of Penicillin by the Lactic Acid-acetone-KBrO3-Mn2+-H2SO4 Oscillating System with Analyte Pulse Perturbation Technique

A rapid and convenient method for the determination of penicillin is presented which is based upon sequential perturbation of the Mn (II)-catalyzed B-Z oscillating system with different quantities of penicillin using a continuous-flow stirred tank reactor (CSTR). The results showed that changes both in oscillating period and amplitude were linearly proportional to the –lgC (where C is the concentration of penicillin) in either the range from 2.97 × 10−7 to 5.50 × 10−5 M or the range of 2.97 × 10−6–5.50 × 10−5 M, with the respective regression coefficients of 0.9981 and 0.9985, respectively. A lower detection limit of 5.94 × 10−8 M was obtained with excellent throughput (15 samples per hour). The Mn (II)-catalyzed oscillating system where lactic acid is included is more interesting for understanding the oscillator in biological system because lactic acid (LA) is an important intermediate product in the metabolic process of human body. A possible mechanism of penicillin perturbation in the oscillating reaction was also discussed.