基于电化学和虚拟仪器的土壤重金属检测系统研究

Detection System of Heavy Metals in Soil Based on Electrochemistry and Virtual Instrument

采用超声波辅助提取法对土壤样本进行快速前处理,以铋膜修饰丝网印刷电极作为传感器,结合差分脉冲阳极溶出伏安法对土壤浸提液中的铅和镉进行精确测量。检测仪器以Lab View平台软件为工作核心,结合MSP430单片机、恒电位电路、I/V转换电路、电磁阀和蠕动泵等硬件设备实现了对土壤浸提液的自动进样、电化学分析以及排液清洗等铅和镉的操作。针对实际土壤样本测量时可能产生的误差,分别采用了概率统计算法以及多次标准添加法加以消除。系统检测限分别达到2.6μg/L和1.8μg/L。对不同地区采集到的多个土壤样本进行分析,结果表明该系统具有检测精度高、重现性好、速度快、功耗低等优点,适合对农田土壤重金属进行快速检测和评估。

A detection system for rapid monitoring heavy metals in soil based on electrochemical and virtual instrument technology was developed. The ultrasonic-assistant extraction technique was used for rapid pretreatment of soil samples. Single use sensors bismuth film modified screen-printed electrodes coupled with differential pulse anodic stripping voltammetry （DPASV） provided a rapid, accurate screening system for the simultaneous determination of cadmium and lead in soil. The control program, developed in LabView, was adopted as control kernel, by combining the MSP430 microcontroller, the potentiostat circuit, I/V conversion circuit, peristaltic pump and electromagnetic valve. This system realized the automatic measurement, The probability statistics algorithms and the standard addition method were employed to overcome the inherent measurement errors existed in real soil analysis and the system detection limits were 1.8 μg/L for cadmium and 2.6 μg/L for lead, respectively. Experimental results showed that the system possesses many advantages such as high precision, good reproducibility, high speed and low power consumption, which was suitable for rapid evaluation and measurement of heavy metals in soil.