毛细管电泳电容耦合非接触电导检测-双端进样同时测定无机阴离子和阳离子

Simultaneous Determination of Inorganic Cations and Anions by Dual Opposite Ends Injection Coupled with Capillary Electrophoresis with Capacitively Contactless Conductivity Detection

利用自研制的电容耦合非接触电导检测器,结合毛细管电泳技术,以2-N-吗啡啉乙磺酸(MES)/组氨酸(His)为缓冲溶液,采用双端进样方式,同时分离测定了5种阴离子和7种阳离子.考察了激发电压值、激发电压频率对检测的影响;缓冲溶液浓度及pH、进样操作对分离的影响.在最佳分离检测条件下,12种无机离子可在4 min内完成测定.阳离子的检出限为0.2 (Na+)～3 μmol/L(Mn2+);阴离子的检出限为0.5(SO2-4)～4 μmol/L (Br-);线性范围可达两个数量级.方法用于实际水样中阴离子和阳离子的测定.

Capillary electrophoresis with capacitively coupled contactless conductivity detection ( C4D) was used for the simultaneous determination of inorganic anions and cations by dual opposite ends introduction. The effects of the alternating current voltage and frequency on the detection sensitivity of C4D, the conceptration and pH of 2-(N-morpholino) ethanesulfonic acid (MES)/histidine (His) running buffer, and the injection mode of sample on the separation of cations and anions were studied. Twelve inorganic cations and anions were determined in less than 4 minutes by the injection mode of cations being first introduced, followed by anions from the oppositecapillary end under the best conditions, which were vltage 200 V, frequency of 200 kHz, 20 mmol/L MES/ 15 nunol/L at pH 5. 0. The detection limits of cations were 0.2 ( Na+) to 3 ( Mn2+) mu mol/L, anions 0.5 (SO42-) to 4 ( Br-) mu mol/L. The responses were linear ( correlation coefficients r = 0. 9957 similar to 0. 9999) over two orders of magnitude. The method could be used for simultaneous determination of both cations and anions in real water samples.