Background: Copper is one of the important elements for human health and requires for normal metabolic processes thus detection of copper ions at micro molar level or less is great importance. The aim of this paper is to introduce a rapid, sensitive and selective method based on AgNPs for the determination of trace amounts of Cu(II) by Uv-vis spectrophotometry. Methods: A colorimetric sensor have been developed using AgNPs for the detection of Cu(II). The 2,2- thiodiacetic acid (TDA) was selected to modify the surface of AgNPs and to improve the selectivity of AgNPs for the detection of Cu(II). Results: In order to optimize determination of copper, various parameters such as TDA concentration, pH and reaction time on aggregation of TDA-AgNPs in the presence of Cu(II) were investigated. Under optimum conditions, the limit of detection was 17 nM. A linear correlation was obtained between the absorbance ratio of A570/A393 and the concentration of Cu(II) in the 0.3 to 6.0 μM range Conclusion: A new selective and economical probe was developed for the detection of copper ions. The preparation of the probe is performed by reduction of AgNO3 in the presence of TDA. The aggregation of AgNPs are based on the interaction of donating groups of TDA with Cu(II). This method successfully applied to determine copper in real water and urine samples and gave recoveries that ranged from 97.5 to 101.1 % with RSD values 0.9–3.4 %.
