An Indirect Inhibitive Immunoassay for Detection of Low Concentration Sulfamethoxazole in Aqueous Solution

A new indirect inhibitive immunoassay using surface plasmon resonance (SPR) coupled with molecularly imprinted polymer (MIP) was developed and applied for the analysis of sulfamethoxazole (SMX). A SMX MIP coating was synthesized in a flexible quartz capillary (30 cm × 0.25 mm i.d.) by in situ polymerization technique. The thickness of the coating was 198 nm illustrated by scanning electron microscope (SEM) image. The detection was conducted on BIAcore 3000 sensor automatically. The MIP-coating capillary was used as online solid phase extraction (SPE) tube before SPR detection. The anti-SMX mono-antibody was inhibited by SMX that was extracted by the MIP coating in a dose-dependent manner. The calibration curve was generated by linear fit in the range of 0.04–10.0 μg L−1. The detection limit of SMX was 0.01 μg L−1. It was directly applied for the analysis of real-world samples. This method has high sensitivity and can be performed automatically.