PIEZOELECTRIC CRYSTAL IMMUNOSENSOR FOR SENSITIVE DETECTION OF METHAMPHETAMINE (STIMULANT DRUG) IN HUMAN URINE

We have developed an immunosensor based on a piezoelectric quartz reso nator, which detects methamphetamine (MA) in liquids from a shift of t he resonant frequency. The sensor has MA-albumin conjugates immobilize d on the resonator and its resonant frequency shifts downward on conta ct with the monoclonal antibody to MA dissolved in the phosphate buffe r solution. Under the condition of a fixed concentration of the antibo dy, the frequency shift is attenuated by mixing MA with the antibody s olution. Based on this principle, it has been possible to detect 0.02- 100 ppm MA with a detection time of about 7 min. The sensor has proved to be sensitive and stable enough to detect the critical concentratio n (1 ppm) of MA in human urine.