Ultrasensitive detection of salbutamol in animal urine by immunomagnetic bead treatment coupling with surface-enhanced Raman spectroscopy

Salbutamol (SAL) is a β 2 -adrenergic receptor, which could produce leaner meat with a higher muscle to fat ratio for livestock, has been prohibited for use in animal farming in many countries because of its harmful effect to the health of consumers. In this study, we present a novel method based on surface-enhanced Raman spectroscopy (SERS) for the sensitive and quantitative detection of trace amount of SAL in animal urine samples by reoxidized graphene oxide/gold nanoparticle hybrids (rGO/AuNPs) substrates and the immunomagnetic bead sample treatment. Compared with the regular graphene/gold nanoparticles (GO/AuNPs) substrates, the rGO/AuNPs substrates by the second oxidization pretreatment exhibited an excellent SERS activity with an enhancement factor of ∼10 8 . Under the optimal detection conditions, the limit of detection of SAL in urine sample is 0.5   ng   mL −1 with a linear response of the matrix-matched calibration standard curves range from 1.0–20   ng   mL −1 , and the recovery of SAL from spiked urine samples are in the range of 85.2–92.5% with the relative standard deviations (RSD) values <3.18%. The inter- and intra- day detection precisions is less than 6.28%, and the storage time of the substrates is no less than 4 weeks under 4   °C temperature. The results of the proposed SERS detection method agree well with those determined by LC–MS/MS, while the detection time is significantly reduced to 15   min/sample. All these are demonstrated to be a reliable, rapid, simple and ultrasensitive analytical method for detecting SAL in urine samples, and could also be applied for the routine monitoring of the illicit use of SAL in animal farming.