毛细管电泳-非接触式电导法直接测定偏硅酸

摘要

采用毛细管电泳-电容耦合非接触式电导检测(CE-C<'4>D),以2.4mmol/L KOH+1.6mmol/L K<,2>HPO<,4>+0.4 mmol/L 十六烷基溴化铵(CTMAB)为电泳运行液,融硅石英毛细管(45cm×50μm,有效长度40 cm),负高压分离(-15 kV),偏硅酸可在6.0 min内实现与基体共存离子的基线分离,线性检测范围为2.0～80.0 mg/L,检出限为0.5mg/L.峰面积的日内和日间的相对标准偏差(RSD)分别为3.5%和3.8%.考察了电泳运行液的组成、浓度以及共存组分的干扰(特别是磷酸盐和有色基体的干扰)对灵敏度和分离度的影响.本方法应用于有色基体和饮用矿泉水中偏硅酸含量的快速灵敏检测,取得满意结果.%A new method for the rapid separation and sensitive determination of silicate in drinking natural mineral water by capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) was developed. The analyte could be separated well within 6 min in a fused-silica capillary under the optimum conditions: 2.4 mmol/L KOH+1.6 mmol/L K2HPO4+0.4 mmol/L CTMAB as the running buffer, CTMAB as the electroosmotic flow modificator, negative polarity separation voltage, -15 kV. The linear response ranged from 2.0 mg/L to 80 mg/L with the LOD=0.5 mg/L. The relative standard deviations of the intra- and inter-day precision were 3. 5％ and 3.8％, respectively. The effects of the component of the running buffer, the interference of PO(34)- and colorants in samples were discussed. Contents of silicate in drinking natural mineral water samples could be easily determined by the proposed method with satisfactory results. It was free from phosphate and colorants interference.