Surface-Enhanced Raman Spectroscopy for Rapid Determination of β-Agonists in Swine Urine

Surface-enhanced Raman spectroscopy (SERS) combined with chemometric method was used for the determination of β-agonists including clenbuterol, salbutamol and ractopamine in standard solutions. For standard solutions, the characteristic bands of SERS spectra could be detected at concentrations as low as 2 μg L−1 for clenbuterol and salbutamol, and 0.1 mg L−1 for ractopmiane; while the R2 of actual values vs. predicted values based on partial least squares (PLS) regression model for the three tested drugs ranged from 0.9134 to 0.9368. For real sample analysis, three β-agonists was artificially added to urine samples (1–20 mg L−1) collected from ten different swine, and then a rapid liquid-liquid extraction (LLE) method was used to extract the targets before SERS analyses. Ractopamine in swine urine could be detected at as low as 1 mg L−1. For quantitative analysis, the R2 of actual values vs. their values predicted by the PLS models was 0.8810. The LLE method followed by SERS detection took less than 30 min for analysis of β-agonists in swine urine, which indicates the method has the potential for the rapid determination of β-agonists in swine urine with SERS technology.