Selective detection of urea as milk adulterant using LMR based Fiber Optic Probe

Adulteration in milk has been a very common practice for economic benefits which is unethical and injurious to health as well. To address the critical issues, the present study reports the detection of a common milk adulterant, urea using a Lossy mode resonance (LMR) based fiber optic sensor. In the work reported herein the ZnO nanorods structure has been synthesized on the fiber-optic probe using hydrothermal process and an additional enzymatic layer of urease has been coated to sense the presence of urea in milk. This additional urease layer makes this sensor selective to detect the urea content in the milk sample. With increasing the urea concentration in milk from 50 to 800 mM, a change in the refractive index is measured, leading to redshifts in the peak wavelengths of absorbance spectra. The proposed sensor's performance parameters have also been calculated using these peak shifts and an 8- fold enhancement in the sensitivity to the non-enzymatic sensor has been observed. Owing to the excellent urea selectivity and quick response time of the proposed sensor, it can be a savior of many health problems like kidney failure, liver damage and other organ impairments.