A wireless magnetoelastic sensor for urinary 2-naphthol detection based on the precipitation of 2-naphthol with diazonium salts.

A wireless magnetoelastic sensor has been developed for the determination of 2-naphthol (2-NAP) in human urine. This method is based on the precipitation of 2-NAP with diazonium salts produced by the diazo-reaction of sulfamethoxazole (SMZ) with nitrite under a weak alkaline condition, resulting in a descending of the resonance frequency of a wireless magnetoelastic sensor. The frequence shift values (ΔF) of the sensor were directly proportional to the concentration in the range of 1.13 - 139 µmol L(-1) for 2-NAP with a correlation coefficient of 0.997 and a detection limit of 0.340 µmol L(-1). The relative standard deviations were 2.38, 2.40 and 2.44%, and the average recovery was 107% (n = 6). The proposed method has additional advantages of being less time-consuming, low cost and remote query, and can be applied for real-time and in situ monitoring of 2-NAP in human urine. It would be a benefit to extend the scope of applications of magnetoelastic sensing techniques.