Application of MIP-sensors to the determination of preservatives in non-alcoholic drinks

Abstract

The piezosensors modified with a molecularly imprinted polymer (MIP) with potassium sorbate (MIP-E202) and sodium benzoate (MIP-E211) imprints are tested and implemented in the determination of preservatives in soft drinks. Molecularly imprinted polymers were synthesized by noncovalent imprinting on the base of copolymer of 1,2,4,5-benzene tetracarboxylic acid dianhydride and 4,4’-diaminodiphenyl oxide in N,N-dimethylformamide (DMF) in the presence of templates. Piezoelectric sensors based on MIP and non-imprinted polymer (polyimide) were compared. High values of the imprinting factor (IF) and selectivity coefficient (k) obtained for MIP-E202 (IF = 5.4) and MIP-E211 (IF = 6.0) sensors indicated better selectivity and ability of MIP-based sensors to recognize target molecules than piezosensors modified with a reference polymer. The detectable concentrations range within 5 – 500 mg/liter, the detection limits for potassium sorbate and sodium benzoate are 1.6 and 2.0 mg/liter, respectively. Correctness of the preservative determination in model solutions was verified using the spike test. MIP-based sensors appeared sensitive to the preservative determination and insensitive to interfering substances. The matrix composition of the non-alcoholic drinks did not affect the value of the analytical signal of the piezoelectric sensor. High performance liquid chromatography (HPLC) was used as a reference method. The results of potassium sorbate and sodium benzoate determination in non-alcoholic drinks using piezosensors match the HPLC data rather well, their content in the studied soft drinks being 130 – 176 and 129 – 146 mg/liter, respectively.