基于十六烷基三甲基溴化铵存在下铅、银离子的高灵敏度电化学测定

Highly Sensitive Electrochemical Determination of Trace Pb^(2+) and Ag^+ In the Presence of Cetyltrimethylamonium Bromide

报道了在适量十六烷基三甲基溴化铵 (CTMAB)存在下 ,高灵敏度测定水体中铅、银离子的化学修饰碳糊电极。在pH 2 .5 0 .1mol LKNO3溶液中 ,铅、银离子在钠型蒙脱石修饰碳糊电极上通过离子交换而富集 ,同时被还原。在阳极扫描过程中 ,分别在 - 0 .5 2V和 0 .2 3V(vs.SCE)处出现灵敏的溶出峰。详细研究了测定水样中铅、银离子的条件 ,如介质的pH、CTMAB用量、修饰剂用量、富集电位和时间等。该修饰电极连续测定铅、银离子的线性范围为 5 .0× 10 - 9mol L～ 1.0× 10 - 7mol L(Pb2 + )和 8.0× 10 - 9mol L～ 1.0× 10 - 7mol L(Ag+ ) ,富集 4min后检出限分别为 1.0× 10 - 1 0 mol L(Pb2 + )和 3.0× 10 - 1 0 (Ag+ )。

In the presence of cetyltrimethylammonium bromide (CTMAB), a sodium montmorillonite (SWy-2) modified carbon paste electrode was examined for the determination of trace levels of Pb2+ and Ag+. CTMAB and SWy-2 greatly improve the sensitivity of the determination of Pb2+, and Ag+. Pb2+ and Ag+ are preconcentrated and reduced on the modified electrode surface at -1.0 V, and then stripped from the electrode surface during the positive potential sweep. The determination parameters, such as supporting electrolyte, pH values, the amount of SWy-2, the amount of CTMAB, accumulation potential and accumulation time were optimized. The peak current is linearly with the concentration over the range of 8, x 10(-9) similar to 1 x 10(-7) mol/L for Ag+ and of 5 x 10(-9) similar to 1 x 10(-7) mol/L for Pb2+. The detection limit (signal-to-noise = 3) is 1.0 x 10(-10) mol/L for Pb2+ and 3.0 x 10(-10) mol/L for Ag+ after 4 min accumulation.