Electrochemical Impedance Spectroscopy based Sensor System for Detection of Detergents in Cow Milk

People, irrespective of age, gender, and geographical location, consume milk in one or another form. Milk is considered as super food and immunity booster due to its ingredients. Adulteration of milk is mostly due to the gap between demand and supply. Water, urea, starch, detergents, formaldehyde, and hydrogen peroxides are commonly used adulterants. Detergent is added to pure milk to reduce microbial growth so that to increase its shelf life. Detergent causes health problems like indigestion, stomach ulcers, and imbalance in the absorption of organic matters in humans. The work presented in this paper focuses on the detection of detergents in cow milk with Electrochemical Impedance Spectroscopy (EIS). A designed EIS sensor setup, with an Impedance analyzer board and Phase shift to voltage converter circuitry are employed to assess the impedance (components like magnitude, phase, or real and imaginary values) of the milk. The impedance of the electrolyte which is milk changes with the addition of detergent. The ionic nature of the detergent is responsible for changes in capacitance and in turn impedance of the sensor. The Sensor is responsive for variation of detergent 0% to 10% in 100ml of milk. The time for detection is around 35 seconds. As the impedance also depends on the frequency, its effect on the impedance is also observed. The presented work proves the EIS method rapid and low cost for detection of detergent in cow milk.