Innovative sensor design for reliable detection of formaldehyde adulteration in milk

Abstract

This research presents a straightforward and cost-effective sensor design for the detection of harmful chemical adulterants in raw milk, with a focus on formaldehyde, a common preservative. The proposed sensor design involves a minimal sample volume of 4 ml and utilizes a low-cost assembly with two nickel electrodes within a plastic cuvette. Electrochemical Impedance Spectroscopy (EIS) was conducted with an LCR meter to record three key electrical parameters: impedance (Z), phase angle (θ), and parallel plate capacitance (Cp). Testing was conducted in a controlled laboratory environment at temperatures between 25 to 27 °C for both unadulterated and adulterated milk samples. The results reveal that Z is the most sensitive parameter, capable of detecting formaldehyde adulteration as low as 0.5%. Conversely, θ and Cp effectively detected adulteration levels exceeding 3%. A noteworthy finding is a consistent and proportional increase in Z ranging from 2.2% to 26.4% as the formaldehyde concentration increases from 0.5% to 10% across a wide frequency range from 10 kHz to 200 kHz. This method offers a dependable and efficient approach to quality control, ensuring the safety and integrity of milk products.