Abstract: A new method for the rapid determinatibn of microgram and submicrogram amounts of pentoxyverine citrate has been suggested using a ringcoated piezoelectric quartz crystal in combination with the neutralization extraction technique. The detection limit is 0.02 μg. Frequency shift is directly proportional to the pentoxyverine citrate concentration in the range of 0.05～1.6 βg, with a correlation coefficient of 0.999 and a coefficient of variation of 2.3%. The new method suggests a number of advantages over the classical neutralization-extraction method.