Development of a strip-based test for detection of urea adulteration in milk

The availability of sophisticated instrumental techniques for adulteration detection in milk is a distant dream for rural areas in India. To address this constraint, a simple chromatographic paper-based test strip for the detection of urea in milk is developed. The said strip was prepared by dipping a chromatographic paper for 10 min in an admixture of a supernatant (coarse ground soybean powder soaked overnight in water) and an acid-base indicator. The strip utilizes the urease naturally present in soybean for the production of ammonia from urea which consequently raises the pH enabling the change in color of the strip. The limit of detection of urea by developed strip is 0.07%. The response time of the strip ranges from 3 to 5 min. The strip was found to be stable for 6 months when stored at ambient temperature with reproducible results. Novelty impact statement A simple, low cost and sensitive strip based test for detection of urea in milk is developed. The strip works on the principle of use of natural urease present in soybean slurry. The limit of detection observed in the test for urea detection in milk is 0.07%.