摘要
Polarographic catalytic wave of chlordiazepoxide in the presence of K 2S 2O 8 was studied in aqueous and DMF/H 2O mixed solutions. The results showed that a single reduction wave in alkaline medium was the reduction of the N=C bond in 1,2 position of chlordiazepoxide via an intermediate free radical in two one electron successive additions. When K 2S 2O 8 was present, the free radical of the N=C bond was oxidized to regenerate the original, producing a parallel catalytic wave of chlordiazepoxide. It was determined that the apparent rate constant k f of the oxidation reaction was 3.2×10 3 mol -1 ·L·s -1 . Using the catalytic wave the trace of chlordiazepoxide can be determined by linear potential scan polarography. In NH 3/NH 4Cl (pH 10.2±0.1, 0.12 mol/L)/K 2S 2O 8 (0.016 mol/L) supporting electrolyte, the second order derivative peak current of the catalytic wave was rectilinear to chlordiazepoxide concentration in the range of 3.20×10 -8 -1.60×10 -7 , 1.60×10 -7 -1.44×10 -6 and 1.44 ×10 -6 -1.44×10 -5 mol/L, respectively. The limit of detection was 9.0×10 -9 mol/L.
Polarographic catalytic wave of chlordiazepoxide in the presence of K 2S 2O 8 was studied in aqueous and DMF/H 2O mixed solutions. The results showed that a single reduction wave in alkaline medium was the reduction of the N=C bond in 1,2 position of chlordiazepoxide via an intermediate free radical in two one electron successive additions. When K 2S 2O 8 was present, the free radical of the N=C bond was oxidized to regenerate the original, producing a parallel catalytic wave of chlordiazepoxide. It was determined that the apparent rate constant k f of the oxidation reaction was 3.2×10 3 mol -1 ·L·s -1 . Using the catalytic wave the trace of chlordiazepoxide can be determined by linear potential scan polarography. In NH 3/NH 4Cl (pH 10.2±0.1, 0.12 mol/L)/K 2S 2O 8 (0.016 mol/L) supporting electrolyte, the second order derivative peak current of the catalytic wave was rectilinear to chlordiazepoxide concentration in the range of 3.20×10 -8 -1.60×10 -7 , 1.60×10 -7 -1.44×10 -6 and 1.44 ×10 -6 -1.44×10 -5 mol/L, respectively. The limit of detection was 9.0×10 -9 mol/L.
基金
ProjectsupportedbytheNationalNaturalScienceFoundationofChina (No.2 9875 0 17)
