双通道毛细管电泳电化学法同时检测硝酸根、亚硝酸根和氯酚类化合物

Simultaneous Determination of Nitrite, Nitrate and Chlorophenols via Capillary Electrophoresis with a Dual-channel Electrochemical Detection System

建立了同时测定环境水样中的硝酸根、亚硝酸根离子和氯酚类化合物的双通道毛细管电泳电化学法。将电导检测器和安培检测器并联,优化了缓冲溶液、工作电极、工作电位和分离高压等实验参数。结果表明,在优化的电泳条件下即-1.0V(vs.SCE)的检测电位、聚酰胺修饰碳糊电极(安培检测),15.0mmol/L硼砂15.5mmol/LKH2PO4(pH=8.6)的缓冲溶液,13kV的分离电压,25μmi.d.×70cm的分离毛细管。6种样品(硝酸根、亚硝酸根离子和氯酚类化合物)在14min内可以实现分离检测,样品的线性范围为0.05～30.0mg/L,检出限为0.02～0.05mg/L,迁移时间和峰高的相对标准偏差(n=8)为2.0%～3.4%。将此法应用于实际废水样品的测定,结果满意,样品的加标回收率为97.2%～106%。

A novel method was presented for simultaneous determination of nitrite, nitrate and chloro-(phenols) by means of capillary electrophoresis combined with a dual-channel electrochemical detection system. Two (detectors), including an amperometric detector and a conductivity detector, were connected in parallel to the same capillary electrophoresis system and were simultaneously performed for detecting all the samples. The effects of some important factors such as buffer, working electrode, working potential and separation voltage on separation were investigated. The results show that under the optimum condition of 25 μm(i.d.)×70 cm(l.) capillary, 13 kV separation voltage, 15.0 mmol/L borax-15.5 mmol/L KH_(2)PO_(4)(pH=8.6) (buffer), PAD modified carbon paste electrode and 1.0 V(vs.SCE) detection potential(amperometric detection), six (samples) were eluted in 14 min, and the detection limits were 0.02～0.05 mg/L. The response was linear in the range of 0.05～30.0 mg/L. The relative standard deviations(n=8) of peak (current) and (migration) time were 2.0%～3.4%. The method was successfully applied to analyze waste water samples with satisfactory (assay) results. Sample recovery rates were 97.2%～106%.