Colorimetric Probe Coupled to Dispersive Liquid–Liquid Microextraction for Determination of Dopamine in Serum

Abstract

In this work, a highly sensitive method using a colorimetric probe coupled to dispersive liquid–liquid microextraction (DLLME) was developed for the quantitative determination of dopamine (DA) in serum. The DA in serum was concentrated by DLLME to increase the detection sensitivity and reduce the matrix effects. After the DLLME process, a colorimetric probe of silver triangular nanoparticles (AgTNPs) was used to detect DA, which was based on the plasma transformation of AgTNPs caused by strong interactions with melamine (MA). The results showed that DA could inhibit the aggregation of AgTNPs induced by MA, resulting in the recovery of the surface plasmon resonance (SPR) peak of AgTNPs. Thus, the DLLME method followed by colorimetric probe detection of DA can be achieved. The parameters affecting the proposed method were optimized, under the optimal conditions, a linear calibration curve was obtained over a concentration range of 5 to 250 nM with a recovery from 94.4 to 101.3%. The detection limit was 1.6 nM (at an S/N ratio of 3). The present method was successfully applied to determine DA in human serum.