Enzymatic biosensor for the electrochemical detection of 2,4-dinitrotoluene biodegradation derivatives

RODRIGUEZ MARCELA C.; MONTI MARIELA R; ARGARAÑA CARLOS E.; RIVAS GUSTAVO A.

TALANTA

Elsevier

Lugar: Amsterdam; Año: 2006 vol. 68 p. 1671 - 1676

0039-9140

In this work, we demonstrate for the first time that 4-methyl-5-nitrocatechol (4M5NC) and 2,4,5-trihydroxytoluene (2,4,5-THT), two compounds obtained from the 2,4-DNT biodegradation are recognized by polyphenol oxidase as substrates. An amperometric biosensor is described for detecting these compounds and for evaluating the efficiency of the 2,4-DNT conversion into 4M5NC in the presence of bacteria able to produce the 2,4-DNT-biotransformation. The biosensor format involves the immobilization of polyphenol oxidase into a composite matrix made of glassy carbon microspheres and mineral oil. The biosensor demonstrated to be highly sensitive for the quantification of 4M5NC and 2,4,5-THT. The analytical parameters for 4M5NC are the following: sensitivity of (7.5 ± 0.1) x 10[5] nAM[-1], linear range between 1.0 x 10[-5] and 8.4 x 10[-5] M, and detection limit of 4.7 x 10[-6] M. The sensitivity for the determination of 2,4,5-THT is (6.2 ± 0.6) x 10[6] nAM[-1], with a linear range between 1.0 × 10[-6] and 5.8 x 10[-6] M, and a detection limit of 2.0 x 10[-7]. Under the experimental conditions, it was possible to selectively quantify 4M5NC even in the presence of a large excess of 2,4-DNT. The suitability of the biosensor for detecting the efficiency of 2,4-DNT biotransformation into 4M5NC is demonstrated and compared with HPLC-spectrophotometric detection, with very good correlation. This biosensor holds great promise for decentralized environmental testing of 2,4-DNT.