Determination of the residual amounts of cefotaxime in liquid media using piezoelectric sensors

Abstract

The goal of the study is to develop a piezoelectric sensor based on a molecularly imprinted polymer (MIP) for the determination of cefotaxime in liquid media. To obtain an antibiotic-selective sensor, the electrode surface of was modified with a molecularly imprinted polymer. A pre-polymerization mixture was prepared using a copolymer of 1,2,4,5-benzoltetracarboxylic acid and 4,4’-diaminodiphenyloxide, and an aqueous solution of cefotaxime in a ratio of 1:1. Then a two-stage thermoimidization was carried out in a drying cabinet at a temperatures of 80 and 120°C. After that, the sensor was cooled to room temperature and placed in distilled water for 24 h. An imprinting factor (IF = 40.9) and a selectivity coefficient were calculated to assess the ability of a sensor with MIP (cefotaxime) to recognize a template molecule. A low selectivity of a MIP sensor with the cefotaxime imprint to other cephalosporin antibiotics is revealed. The experiments were carried out on an original installation including a piezoelectric sensor, a portable generator, and an MP732 USB-frequency meter connected to a computer. Piezoelectric quartz resonators of AT-cut with silver electrodes with a diameter of 5 mm and a thickness of 0.3 mm with a nominal resonant frequency of 4.00 MHz were used as sensors. The determination of antibiotics in model solutions was carried out by the method of calibration schedule. The range of detectable concentrations (0.1 – 1.0 × 10–4 g/dm3) was experimentally determined. The detection limit of cefotaxime is 1.0 × 10–5 g/dm3. The correctness of the cefotaxime determination of in individual and binary model solutions was verified by the «spike-test». It has been shown that a sensor with MIP-cefotaxime is not sensitive to an extraneous antibiotic. The relative standard deviation does not exceed 10 %.