Development and characterization of electrochemical sensors for residual determination of tricaine (MS-222) and benzocaine in fish

Abstract

During the aquaculture management process, anesthetics are used in order to stagnant fish and facilitate production activities. This makes there a fish meat quality improvement, because reducing the stress to the animal; the final product has better meat texture, besides reducing the mortality rate during production. However, the misuse of these chemicals can leave residual traces in fish meat, generating concern about the consumer's food safety. In this sense, the objective in this work was to develop efficient electrochemical/electroanalytical methodologies for the application in the determination of residual anesthetics in fish fillets. In the first article, the study of electrosynthesis of an electrode based on a conductive organic polymer associated with carboxylic acid functionalized carbon nanotube (GCE/PANI-MWNT's) was carried out using the cyclic voltammetry technique, wherein the parameters were optimized using statistical technique of fractional factorial planning. In this work, it was possible to correlate electrochemical tests with two levels and six factors (26-1) and optimize the electrode preparation, characterized by FTIR and Raman analyze. In the second article, the electrode (GCE/PANI-MWTC's) was applied in the residual determination of tricaine in fish using the voltammetric DPV technique. For the electrode characterization, the EIS technique was used, demonstrating the relation of the potential scanning cycle and the polymer chain formation. The analytical method developed showed detection limits 2.08 x 10-8 mol L-1 and the quantification 4.00 x 10-8 mol L-1 with correlation coefficient 0.9905. The extraction method presented efficiency in the tricaine determination of fish filet with recovery 90% ± 4%. In addition, proposals were made of mechanisms interaction between polyaniline (PANI), carboxylic acid functionalized carbon nanotube (MWTC's) and tricaine anesthetic. In the third article, benzocaine and residual tricaine were determined in fish fillets using a printed carbon electrode using BIA methodology. It was possible to obtain more than 300 injections per hour with low detection limits 3.02 x 10-8 mol L-1 for benzocaine and 3.19 x 10-8 mol L-1 for tricaine, using only 80 mL of sample for each analysis, with high repeatability and good recovery rate of both anesthetics > 99%.