Carapuça Helena M, Cabral David J, Rocha Luciana S
Department of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
J Pharm Biomed Anal. 2005 Jun 15;38(2):364-9. doi: 10.1016/j.jpba.2005.01.005.
The adsorptive stripping voltammetric behaviour of trimethoprim (TMP) was studied at pH 3.8 and 7.0 by linear-sweep (LS) and cyclic voltammetry at the hanging mercury drop electrode. The charges and surface concentrations of the protonated TMP species were determined at both pH values. Taking advantage of the adsorption features of TMP fast voltammetric techniques (LS and square-wave (SW) voltammetry) were applied to the determination of TMP at the 10(-7)mol dm(-3) concentration level (pH 3.8). For these concentrations the relative standard deviations were <2% (N=8) and the detection limit was 10nM (3 ng/mL) for the SW-AdCSV (3s; accumulation time 10s, frequency 100 Hz). The use of SW-adsorptive cathodic stripping voltammetry originated a very fast and sensitive method for the direct analysis of TMP in pharmaceutical suspensions without any matrix effects or interference from sulfamethoxazole. No sample pre-treatments or solvent extraction procedures were needed. The quantitative results were in agreement with the data supplied by the manufacturer.
采用线性扫描（LS）和循环伏安法，在悬汞滴电极上研究了甲氧苄啶（TMP）在pH 3.8和7.0条件下的吸附溶出伏安行为。测定了两个pH值下质子化TMP物种的电荷和表面浓度。利用TMP的吸附特性，将快速伏安技术（LS和方波（SW）伏安法）应用于10⁻⁷mol dm⁻³浓度水平（pH 3.8）的TMP测定。对于这些浓度，相对标准偏差<2%（N = 8），SW-AdCSV（3s；富集时间10s，频率100Hz）的检测限为10nM（3ng/mL）。SW吸附阴极溶出伏安法的使用产生了一种非常快速且灵敏的方法，可直接分析药物悬浮液中的TMP，而不会受到任何基质效应或磺胺甲恶唑的干扰。无需样品预处理或溶剂萃取程序。定量结果与制造商提供的数据一致。
