Quantifying colorimetric assays in µPAD for milk adulterants detection using colorimetric android application

Abstract

A microfluidic paper-based analytical device (μ-PAD) and handheld colorimeter android application for quantifying the precise concentration of adulterants in milk are developed. A simple method to pattern polydimethylsiloxane for creating a hydrophobic barrier on filter paper using custom-designed rubber stamp containing the design of μ-PAD was used. The experiments were performed for the detection of urea, starch, salt and detergent ranging from 1 to 100 mg in 10 ml of milk. The user just needs to pipette drops of adulterated milk on a test spot and the results are obtained instantly. The authors believe that the developed platform can be used as a basis for low-cost, portable system for various fluid adulterants’ tests. The experimental database was used for the development of a colorimetric android application to calibrate the colour range for adulterants’ concentration detection. The limit of detection of colorimetric android application for adulterants urea is 5 mg, starch is 17 mg, salt is 29 mg and for detergent is 20 mg in 10 ml of milk. This kind of system is attractive for use in developing countries, in the field, or as an inexpensive alternative as compared with other methods for water and food safety.