Nitrate quantification: recent insights into enzyme based methods
Abstract Nitrate monitoring of environmental samples is essential to safeguard human and environmental health. Various non enzymatic methods such as Griess reaction based chemical method; Fourier transform infrared spectroscopy; chromatographic, electrochemical and optical sensors yield reproducible results but suffer from drawbacks such as use of hazardous chemicals, interference from coexistent anions, and bulky and expensive instrumentation and hence are not favored for routine analysis. On the other hand, nitrate reductase (NR) based methods are simple, sensitive, specific, environment friendly, easy to carry out, and, therefore, suitable for routine analysis. NR in these methods is employed in both free (in commercially available kits) and immobilized form. In comparison to the native NR, immobilized NR shows better activity and stability accompanied by overall reduction in the cost of the method. The review gives a brief account of non enzymatic nitrate quantification, whereas recent advances in enzyme based determination have been explored in more detail.