Nitrogen doped tetrahedral amorphous carbon (ta-C:N) thin films were deposited on p-Si (111) substrates (1×10−3 to 6×10−3 Ωcm) by a filtered cathodic vacuum arc technique with different nitrogen flow rates (3 and 20sccm). The ta-C:N film coated samples were used as working electrodes to detect trace heavy metals such as zinc (Zn), lead (Pb), copper (Cu) and mercury (Hg) by using linear sweep anodic stripping voltammetry in 0.1M KCl solutions (pH 1). The influence of nitrogen flow rate on the sensitivity of the films to the metal ions was investigated. The results showed that the current response of the ta-C:N film electrodes was significant to differentiate all the tested trace metal ions (Zn2+, Pb2+, Cu2+, and Hg2+) and the three ions (Pb2+ +Cu2+ +Hg2+) could be simultaneously identified with good stripping peak potential separations.