Development of a novel electrochemical sensor based on cobalt(II) complex useful in the detection of dopamine in presence of ascorbic acid and uric acid

•Dopamine could be determined in human urine sample.•Cobalt complex improved sensitivity.•The modified electrode showed good reproducibility.•Ascorbic acid and uric acid not produce significant interference.•The samples needed no pre-treatment.

[(Co(bdmpzm)2(NCS)2] (bdmpzm = bis(3,5-dimethylpyrazol-1-yl)methane) was synthesized and combined with single walled carbon nanotubes (SWCNT) and nafion on a screen printed carbon electrode (SPCE). The electrocatalytic activity of modified electrode (Nafion-SWCNT-[Co(bdmpzm)2(NCS)2]/SPCE) was evaluated for dopamine (DA) oxidation. Anodic and cathodic peak were seen to 0.42 V.and0.29 V respectively, showed a much more quasi-reversible process, (∆ V 0.128) compared with the electrode without cobalt complex. The detection limit (3σ/b) for dopamine was 0.095 μmol L− 1. The studies of reproducibility determined as relative standard deviation (RSD) was 2.5%.(n = 5) with four different electrodes. The repeatability were 1.5% (n = 5) The new sensor was used in the quantify DA in human urine with an average recovery between 83.0 and 93.0%.