Environmental pollution by heavy metals is a serious issue, as these metals in the body, leading to toxicity and diseases. To effectively monitor trace levels of heavy metals in-situ, electrochemical technique is well-suited due to their fast analysis, ease of operation, and compatibility with small circuit for portable applications. A key challenge in developing an electrochemical device is ensuring its capability to detect small current changes in an electrochemical cell, particularly at levels corresponding to the permissible standard limits of heavy metal elements. This study aims to analyze the performance of the current measurement part of the electrochemical device to ensure its sensitivity to small current changes within permissible standard limits. To achieve this, the transimpedance amplifier gain and the cell replication were carefully designed. Five values of cell replications and transimpedance amplifier gains were selected based on the estimated current range for copper detection. Performance was analyzed in terms of noise measurement and error rate. The noise analysis results showed that although the output noise increased with higher resistance values and signal gain, the signal to noise ratio (SNR) remained above one. In term of error rate performance, the lowest error rates were observed with transimpedance amplifier gain of 1 kΩ, 10 kΩ, and 1 MΩ, and 10 MΩ for operating currents of 1000 µA, 100 µA, 10 µA, 1 µA, and 0.1 µA, respectively. This indicates that good performance of the current measurement part was achieved by selecting a suitable transimpedance amplifier gain based on the operating current range.