Preparation and application of a trimethoprim ion-selective piezoelectric sensor

PVC film containing various activants was coated on one electrode of a thic kness-shear mode piezoelectric quartz crystal (PQC) to fabricate a trimetho prim (TMP) ion-selective piezoelectric sensor for the determination of TMP. The method is based on the selective adsorption of TMP ion on the modified film and the sensitive mass response of the PQC. The method was found to b e sensitive, rapid and easy to handle with no need for previous sample trea tment. The logarithm of frequency shift of PQC was found to bear a linear r elationship to the logarithm of the concentration of TMP over the range 2 x 10(-8)-2 x 10(-3) M with a detection Limit of 2 x 10(-8) M at pH 4.0. Reco veries were from 99-102.9%. Two activants, TMP phosphotungstate and TMP sil icotungstate, were synthesized and investigated. Influencing factors were e xamined in detail and optimized. The results for real samples obtained by t he proposed method agreed with those obtained by a conventional method.