Highly Sensitive Detection of Clenbuterol in Animal Urine Using Immunomagnetic Bead Treatment and Surface-Enhanced Raman Spectroscopy

Combining surface-enhanced Raman spectroscopy (SERS) of aggregated graphene oxide/gold nanoparticle hybrids with immunomagnetic bead sample preparation method, a highly sensitive strategy to determine the clenbuterol content in animal urine was developed. Based on a linear calibration curve of the SERS characteristic peak intensity of clenbuterol at Δv = 1474 cm(−1) versus the spiked clenbuterol concentration in the range of 0.5–20 ng·mL(−1), the quantity of clenbuterol in real animal urine samples can be determined and matches well with those determined by LC-MS/MS, while the detection time is significantly reduced to 15 min/sample. The limits of detection and quantification in the urine are 0.5 ng·mL(−1) and 1 ng·mL(−1), respectively, and the recovery clenbuterol rates are 82.8–92.4% with coefficients of variation <9.4%. The day-to-day variation of the detection is less than 6.41%, and the shelving life of the SERS substrates is no less than 4 weeks. All these indicate that this proposed SERS detection protocol for clenbuterol is reproducible, reliable, and can be easily developed for the routine monitoring of the illicit use of clenbuterol in animal farming.