P-013

Ernestas Brazys

ernestas.brazys@chgf.stud.vu.lt

Vilma Ratautaite, Arunas Ramanavicius

Department of Physical Chemistry, Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Lithuania

Development of an Electrochemical Sensor for Detecting Melamine

Melamine is a compound widely used in the plastics industry to produce resins. However, its unethical use by manufacturers to artificially boost protein content in dairy products has been well-documented. A notable instance occurred in 2008 when melamine-tainted milk in China led to the development of urinary stones in children under three years old [1]. Melamine is toxic to human kidneys, and its ingestion can result in renal diseases. This study explores the detection of melamine using molecularly imprinted polypyrrole [2].

The molecular imprinting process involves three main stages: 1) self-assembly of monomers, cross-linkers, and template molecule complexes; 2) polymerization; and 3) removal of the template, forming specific binding sites in the polymer structure [3]. This allows the creation of sensors designed for targeted detection.

In this study [2], a melamine-imprinted polypyrrole-based (MIP) sensor was developed. The pre-polymeric mixture contained 50 mM of pyrrole and 5 mM of melamine in a 10 mM PBS solution (pH 7.4). The polymeric layer was electrochemically deposited on a graphite electrode using potential pulses, and the template was extracted with 1 M H2SO4 solution for 60 minutes. In addition, MIP layers were modified with gold nanoparticles (AuNPs) of 3.5 nm, 6 nm, and 13 nm diameters, along with gold(I) complexes during polymer preparation.

The properties of all polypyrrole films were evaluated using differential pulse voltammetry (DPV) in PBS with a 5 mM K3[Fe(CN)6]/K4[Fe(CN)6] redox probe. The interaction between melamine and the polymer layers was assessed by comparing oxidation peak currents and calculating the apparent imprinting factor. The optimal results were obtained with the MIP modified with 0.05 nM AuNPs of 3.5 nm diameter.

References:

[1] A. K. -C. Hau, T. H. Kwan, P. K. Li. Melamine toxicity and the kidney. Journal of the American Society of Nephrology, 20 (2009).

[2] E. Brazys, V. Ratautaite, B. Brasiunas, A. Ramanaviciene, L. Rodríguez, A. Pinto, D. Milea, U. Prentice, A. Ramanavicius. Molecularly imprinted polypyrrole-based electrochemical melamine sensors. Microchemical Journal, 199 (2024).

[3] V. Ratautaite, E. Brazys, A. Ramanaviciene, A. Ramanavicius. Electrochemical sensors based on l-tryptophan molecularly imprinted polypyrrole and polyaniline. Journal of Electroanalytical Chemistry, 917 (2022).