阳极溶出镉在线分析仪的同步校正方法

Simultaneous calibration method of cadmium on-line analyzer based on anodic stripping voltammetry

针对基于阳极溶出伏安法水质镉在线分析仪溶出峰的电流值受环境温度影响问题,提出了一种同步校正的改进方法。该方法利用样品和校正液溶出峰电流信号随温度同步变化特性,在一个样品测量周期内同时进行校正液的测定,并将两者的溶出峰电流线性比较而计算出样品浓度。实验结果表明,镉溶出峰电流值随温度的升高而增大,当温度从5℃上升至43℃时,溶出峰电流值增大了近2.3倍,且影响机制为镉离子在工作电极表面扩散层的迁移速率主要受温度控制。采用改进的同步校正方法,镉在线仪器在5~43℃测量值的误差均小于10%,有效解决了仪器测量值对环境温度敏感问题。

Aiming at temperature effect on stripping peak current of water cadmium analyzer based on anodic stripping voltammetry,a modified simultaneous calibration method is proposed.In the proposed method,standard solutions are simultaneously measured in the period of sample measurement.And sample concentration is calculated by linear comparison of standard solutions and sample stripping peaks.Experimental results indicate the current of cadmium stripping peaks gradually enhanced with temperature increased,while the current of stripping peak increases about 2.3 times from 5.0°C to 43°C.Diffusion rate of cadmium ions within diffusion layer on working electrode surface is dominated by the solution temperature,which is the main mechanism of temperature effect on stripping peak currents.A modified simultaneous calibration method used for analyzer is introduced to eliminated this effect.Test results show that the measurement errors are less than 10% ranged from 5.0°C to 43°C with this simultaneous calibration method,which proves the efficiency in avoiding environmental effect on measured values.