A fast and simple procedure for simultaneous determination of propyphenazone (PRO), paracetamol (PAR) and caffeine (CAF) was performed using batch injection analysis with multiple pulse amperometric detection (BIA-MPA). Three potentials pulses were selected for the analysis: +0.90 V/50 ms: only PAR was oxidized; +1.20 V/50 ms: oxidation of PAR and PRO without the interference of CAF; +1.60 V/50 ms: oxidation of the three compounds (PAR, PRO and CAF). The sample aliquot (150 µL) was directly injected onto the boron-doped diamond (BDD) electrode immersed in a BIA cell. The analytical characteristics of the proposed method include high analytical frequency (75 injections per hour), good stability (RSD < 3.9%; n = 10), and low detection limits (0.3, 0.2 and 0.1 mg L−1 for PRO, PAR and CAF, respectively). The proposed method yielded similar results to those obtained by liquid chromatography at a 95% confidence level.

<p>A fast, simple procedure for simultaneous determination of sulfamethoxazole (SMX) and trimethoprim (TMP) was performed using batch injection analysis with multiple pulse amperometric detection (BIA-MPA). The sample aliquot (150 µL) was directly injected onto the boron-doped diamond (BDD) electrode (wall-jet configuration) immersed in a BIA system. The analytical characteristics of the proposed method include high analytical frequency (up to 75 injections per hour), good stability (RSD < 2.9%; n = 10), low detection limits (0.227 and 0.173 mg L^-1 for SMX and TMP, respectively) and minimal waste generation. The proposed method yielded similar results to those obtained by liquid chromatography at a 95% confidence level.</p>