DEVELOPMENT OF AN ANALYTICAL METHOD FOR THE DETERMINATION OF LEAD BASED ON LOCAL SURFACE PLASMON RESONANCE OF SILVER NANOPARTICLES

Lead is environmental pollutant that even in low trace is harmful for human health and wildlife. In this study we presented a colorimetric method for determination of Pb2+ in water by aggregation of silver nanoparticles capped citrate in the presence of deferoxamine as chelating agent. Silver nanoparticles were prepared by reduction of AgNO3 with NaBH4. In the presence of Pb2+, mixture of silver nanoparticles capped citrate and deferoxamine aggregated and color of solution changed from light yellow to violet that depends on Pb2+ concentration. As a result of aggregation, local surface plasmon resonance (LSPR) band of silver nanoparticles around 440 nm decreases and a new band appears at 580 nm that depend on Pb2+ concentration. Under optimized conditions, linear relation of concentration of Pb2+ and absorbance ratio (A580/A440), was from 0.19 to 1.29 µmol L-1 and limit of detection of 0.056 µmol L-1 was found. Control experiments with the addition of 10 other metal ions (Ni2+, Cu2+, Ca2+, Al3+, Co2+, K+, Ba2+, Zn2+, Mg2+, Hg2+) did not result in a distinct change in the color or in the absorption spectra. This approach was successfully tested for determination of Pb2+ in well and tap water.

铅是一种环境污染物，即便处于极低痕量水平，也会对人体健康与野生生物造成危害。本研究报道了一种比色检测方法，用于水体中Pb²+的定量分析：以脱铁胺作为螯合剂，利用柠檬酸根包覆的银纳米粒子在Pb²+存在时发生的聚集反应实现检测。银纳米粒子通过硼氢化钠还原硝酸银（AgNO₃）制得。当体系中存在Pb²+时，柠檬酸根包覆银纳米粒子与脱铁胺的混合溶液会发生聚集，溶液颜色由浅黄色变为紫色，且颜色变化程度与Pb²+浓度相关。聚集反应发生后，银纳米粒子在约440 nm处的局部表面等离子体共振（Local Surface Plasmon Resonance, LSPR）吸收峰强度降低，同时在580 nm处出现新的吸收峰，且峰强变化同样与Pb²+浓度相关。在优化后的实验条件下，Pb²+浓度与吸光度比值（A580/A440）在0.19至1.29 μmol·L⁻¹范围内呈良好线性关系，方法检出限为0.056 μmol·L⁻¹。通过添加10种其他金属离子（Ni²+、Cu²+、Ca²+、Al³+、Co²+、K+、Ba²+、Zn²+、Mg²+、Hg²+）进行对照实验，结果显示体系颜色与吸收光谱均未出现明显变化。该方法已成功应用于井水与自来水中Pb²+的定量检测。