Rapid detection of sulfaguanidine in fish by using a photonic crystal molecularly imprinted polymer

A photonic crystal (PC) sensor was prepared through molecular imprinting by using dispersed SiO 2 microspheres as PC, sulfaguanidine (SG) as template, methacrylic acid as monomer, and ethylene glycol dimethacrylate as crosslinker. The preparation conditions were optimized as follows: molar ratio of template, monomer, and crosslinker was 1:10:4; pH was 6.0 in phosphate buffer; and volume fraction of methanol was 15%. The relationship between wavelength shift of reflection peak and SG concentration was found as: Δλ = 7.8887 lg(C) + 79.9664. The response time was only 5 min. The limit of detection was 2.8 × 10 −10  mol L −1 . The sensor exhibited higher specificity for SG than its sulfonamide analogs. The sensor maintained original sensing performance after five cycles of usage. The recoveries of SG ranged from 93.8% to 111.2% in lake water and from 88.5% to 115.2% in fish samples. This finding suggested that the sensor can be used in food samples with complicated matrix.