以聚乙烯吡咯烷酮作为分散剂，柠檬酸三钠作为还原剂，液相还原法合成纳米银（AgNPs）溶胶。采用AgNPs催化溶液中溶解氧氧化3，3'，5，5'-四甲基联苯胺（TMB）后，生成蓝色的TMB氧化物（oxTMB），Hg²⁺的存在会抑制AgNPs的催化效果，使体系蓝色变浅，从而达到监测水中Hg²⁺的目的。方法对Hg²⁺具有良好的选择性。优化的条件如下:反应时间2 min，反应温度20℃，2 g·L^-1 TMB溶液的用量200 μL，AgNPs溶胶用量300 μL。Hg²⁺的线性范围为1×10^-7~1×10^-6mol·L^-1，检出限为0.01 mg·L^-1。方法用于水样的分析，回收率为98.0%~102%，测定值的相对标准偏差（n=5）小于2.0%。

Silver nanoparticles (AgNPs) sol were synthesized by the liquid phase reduction method, with polyvinyl pyrrolidone as the dispersant and trisodium citrate as the reductant. The blue oxTMB was formed after oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) with dissolved oxygen in solution by the catalytic action of AgNPs. The presence of Hg²⁺ could inhibit the catalytic effect of AgNPs, and the color of the above system became lighter. Thus a method monitoring of Hg²⁺ in water was obtained. The proposed method had a good selectivity for Hg²⁺. The optimization conditions found were as follows: reaction time was 2 min, reaction temperature was 20 ℃, amount of 2 g·L^-1 TMB solution was 200 μL, and amount of AgNPs sol was 300 μL. Linearity range of Hg was obtained in the range of 1×10^-7 to 1×10^-6mol·L^-1 with detection limit of 0.01 mg·L^-1. The proposed method was applied to the analysis of water samples, giving values of recovery found by standard addition method in the range of 98.0%-102% and RSDs (n=5) of determined values less than 2.0%.