BULK ACOUSTIC-WAVE BIOLOGICAL DETECTION OF CEFOTAXIME SODIUM

A bulk acoustic wave (BAW) impedance sensor has been applied to rapid determination of in vitro concentrations of cefotaxime sodium. The met hod based on the growth frequency curve of Proteus Morganii, inhibited by cefotaxime sodium, is continuously monitored by using a BAW impeda nce sensor. The growth kinetic parameter, e.g. asymptote or maximum fr equency shift (A(F), HZ), estimated by fitting a modified Gompertz mod el to the growth frequency curve, is proportional to the logarithm of antibiotic concentration. The proposed method exhibits a favourable re sponse to 0.25 - 20.0 mu g mL(-1) cefotaxime sodium with a detection l imit of 0.03 mu g mL(-1), and the recoveries range from 97.3 to 107.5% (n=9). The results are in good agreement with those obtained by the c onventional disk diffusion test (DDT) method. The effects of temperatu re and pH on the determination are discussed and in vitro susceptibili ty to cefotaxime of the genus Proteus has been investigated in detail.