MJAS

Manuscript Details

Enzyme Inhibition Sensor for Malachite Green and Leuco- Malachite Green Detection in Tilapia Fish

Faridah¹*, S., Nurul Hidayah¹, A. P., Gayah¹, A.R., Fatimah², A. B., Nur Azura¹, M.S., Othman³ ,M. and Zamri¹ ,I.

¹Biotechnology Research Centre, Malaysian Agricultural Research and Development Institute (MARDI), Serdang, Selangor.
²Faculty of Food Science and Technology, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.
³Fishery Research Institute, Batu Maung, Penang, Malaysia

Malaysian J. Anim. Sci. 2013 16(1): 1-11

Click to view the abstract

Malachite Green (MG) and Leuco-Malachite Green (LMG) are chemicals extensively used as anti-fungal and anti-parasite agents in the aquaculture industry. Over dosage of these chemicals is hazardous to human health and environment. Detection of MG and LMG is essential for quality and safety monitoring of aquaculture products to meet international standards and to ensure acceptance by foreign markets. An electrochemical enzyme inhibition sensor on screen-printed carbon working electrode with onboard carbon counter and silver?silver chloride pseudo-reference electrode MG and LMG detection is described in this paper. The detection was based on the inhibition of MG and LMG towards butyryl-cholinesterase enzyme (BuChE) in the presence of butyryl- thiocholine substrate on the sensor surface. The mixtures of BuChE enzyme (4 UmL-1) and polypyrrole matrix (75 mM) were electro- polymerized on the sensor surface with a constant potential of 1.0V for 20 minutes. The sensor was soaked for 5 minutes with MG and LMG standard or sample containing MG and LMG before the electrochemical measurement was taken by adding butyryl- thiocholine substrate in KCl (0.08M, pH 7.5) which acts as the enzyme mediator/substrate system. The current measurement was conducted using chronoamperometry at 400mV vs. on board screen-printed Ag-AgCl pseudo- reference electrode. MG and LMG lowest detection limit of 0.25 ppb was achieved. The optimal sensor configuration was then compared to a conventional LC-MS/MS method for analyzing fish samples. The sensor showed good selectivity for MG and LMG with higher recovery percentage (60 - 80%) in the presence of other compounds in the sample matrix. It also showed very high sensitivity using the amplification strategy applied with the use of gold nanoparticles and conductive poly- pyrrole polymer. This makes the developed sensor a potential tool for the rapid, simple and sensitive detection of MG and LMG residues in the aquaculture industry.