Rapid and sensitive determination of clenbuterol residues in animal urine by surface-enhanced Raman spectroscopy

A rapid, selective, and quantitative method to determine clenbuterol content in animal urine based on Surface-Enhanced Raman Spectroscopy (SERS) by aggregated re-oxidized graphene oxide/Au nanoparticle (roGO/AuNPs) hybrids and liquid-liquid extraction has been proposed in this study. To realize the quantitative calculation, melamine was optimized as the internal standard. The peak intensity of melamine observed at Delta v = 709 cm(-1) was first set to 1000 as basis, and the peak at Delta v= 1474 cm(-1) was selected as the characteristic peak of clenbuterol used for the quantitative calculation. Sufficient linearity was obtained in the range of 1-20 ng mL(-1) (R-2 = 0.997). The limit of detection and quantification in urine matrix were as low as 0.5 and 1 ng mL(-1), respectively. The recovery rates were 78.6-89.4% with coefficients of variation less than 9.8%, and the storage time of the substrates is approximately 180 days under 4 degrees C. The detection results of the developed SERS detection method agree well with those determined by LC-MS/MS, while the cost time significantly reduced to 8 min/sample. This new protocol could be easily developed for the routine monitoring of the illicit use of clenbuterol in animal farming.