用于Pb2+、Hg2+离子选择性固相萃取的微流控芯片

Microfluidic chip for selective solid phase extraction of Pb2+ and Hg2+

摘要:

为实现微流控芯片对重金属Pb²⁺、Hg²⁺离子的选择性固相萃取，首先采用3-氯丙基三甲氧基硅烷和5-甲基苯并三氮唑对纳米二氧化硅进行硅烷偶联改性，随后以改性纳米二氧化硅为基础，设计并制备了可更换吸附剂的一体化填充式固相萃取芯片.测试结果表明：改性后不仅吸附剂的团聚现象得到明显改善，且当pH=5时，对Pb²⁺的吸附率可达99.1%，对Hg²⁺的吸附率可达98.9%，而对Cr³⁺的吸附率为20.4%，对Mn²⁺的吸附率仅为13.2%.即使样品中混有干扰离子 (K⁺、Na⁺或Mn²⁺) 时，对Pb²⁺、Hg²⁺离子的吸附率仍均可达97%以上.当进样流速≤1.5 mL/min时，微流控芯片对Pb²⁺或Hg²⁺的吸附率可达98%以上；以0.5 mol/L的盐酸和2%的硫代尿素为洗脱液，控制流速在0.2~0.3 mL/min范围内时，芯片对Pb²⁺或Hg²⁺的洗脱率均达到92%以上.用于Pb²⁺、Hg²⁺离子的选择性固相萃取芯片的成功制备，有助于微流控技术在重金属污染监测领域的应用和推广.

Abstract:

To achieve the selective solid-phase extraction of Pb²⁺ and Hg²⁺ ions by microfluidic chip, the surface modification of nano-silica was carried out by using 3-chloropropyltrimethoxysilane and 5-methylbenzotriazole. And then, an integrated solid-phase extraction chip with replaceable adsorbent was designed and prepared based on the modified nano-silica. The results show that, the agglomeration of the adsorbent is improved significantly. When pH=5, the adsorption rates of Pb²⁺ and Hg²⁺ are 99.1% and 98.9% respectively, while the adsorption rates of Cr³⁺ and Mn²⁺ are only 20.4% and 13.2% respectively. In addition, the absorption rates of Pb²⁺ and Hg²⁺ are both more than 97% even when mixing with the interference ions (K⁺, Na⁺ or Mn²⁺). When the sample flow rate is no more than 1.5 mL/min, the microfluidic chip adsorption rate of Pb²⁺ or Hg²⁺ are both more than 98%; when using the hydrochloric acid (0.5 mol / L) and 2% thiourea [CS (NH₂)₂(W/W)] as eluent, the elution rate of Pb²⁺ or Hg²⁺ is both more than 92% (the flow rate is between 0.2~0.3 mL/min). The successful preparation of selective solid-phase extraction chips for Pb²⁺ and Hg²⁺ contributes to the application and popularization of microfluidic technology in heavy metal pollution monitoring.