Biocatalytic spectrophotometric method to detect paracetamol in water samples

Abstract

A biocatalytic methodology based on the quantification of the laccase inhibition during the oxidation of a standard substrate ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) for the indirect determination of paracetamol in drinking water has been developed. The method displayed a fast response time (20 s), and high selectivity to paracetamol in presence of interfering substances such as naproxen, estradiol, ketoprofen, sulfamethoxazole, and diclofenac. The limit of detection (LOD) and limit of quantification (LOQ) were noticed to be 0.55 µM and 8.3 µM, respectively. By comparing the catalytic constants value K_M and k_cat for ABTS oxidation in the absence and presence of various concentrations of paracetamol, a competitive-type inhibition was disclosed. On the other hand, the close value between K_i and K_M indicates similar binding affinity of the enzyme to ABTS and paracetamol corroborated by docking studies. The methodology was successfully applied to real water samples, presenting an interesting potential for further development of a biosensor to paracetamol detection.

Keywords:

• Emerging pollutants
• laccase
• paracetamol
• pharmaceuticals
• pollutant detection

Funding

The authors acknowledge the following sources of funding: Red Temática BIOCATEM (Grant 245413), CONACyT 204317 (Alia Méndez--Albores) and 206143 (Georgette Rebollar-Pérez).