Kinetic Determination of Urea in Milk Powder by Nonlinear Chemical Fingerprint Technique

To detect urea content in milk powder, a nonlinear chemical fingerprint technique was developed. In our study, Belousov-Zhabotinsky oscillatory chemical reaction (B-Z) was performed using milk powder and malonic acid as main dissipative substances. The same dosage of milk powder with or without artificially added urea was introduced to “H+ + Ce4+ + 3 BrO − + malonic acid” oscillating system, respectively, and nonlinear chemical fingerprints of different milk powder were thus obtained. The proposed method was based on a linear relationship between inductive time of nonlinear chemical fingerprints and urea content in milk powder, which held when urea content in milk powder was in the range of 0 40 mg/g. A detection limit of 7.8 × 10−3 mg/g was also obtained. Our results showed that the method could be used to certify urea content in milk powder without pretreatment of samples, which was more simple and economical compared with traditional methods.