Detection of morphine in urine based on a surface plasmon resonance imaging immunoassay

Based on the surface plasmon resonance imaging (SPRi) technique, a new detection method for morphine in urine samples was developed. Sample labelling was not required, and qualitative and quantitative analysis could be completed in 20 minutes. According to an indirect competitive immunoassay, the mixture of morphine at different concentrations and morphine antibody at a certain concentration as the mobile phase was reacted with morphine BSA fixed on a chip surface in a competitive way. A calibration curve was obtained by correlating the signals generated from SPRi with the concentrations of morphine. By the addition of morphine to a blank urine sample, this method was confirmed to be feasible for the detection of morphine in actual urine. The limit of detection was as low as 9.59 ng/mL. This method is fast and sensitive and can be applied in many fields.