Advantages of nitrate determination by use of e. coli cells in different matrices

Abstract

The applicability of the nitrate determination with the E. coli reduction method has been tested for plant, soil, and water analysis on a wide range of different samples. Recovery rates of added nitrate have been determined and comparisons with other standard nitrate determination methods have been carried out. The recovery of nitrate was complete in all tested samples. The results with the E. coli reduction method agree good with those gained by the standard analytical procedures. The E. coli method can be used manually as well as in automated procedures like flow injection analyzer or segmented flow analyzer. The advantages of the E. coli method in comparison to other nitrate determination methods are: (1) specific reduction of nitrate, (2) no health risk to laboratory staff, and (3) no harmful wastes. Compared to the use of isolated enzymes the advantages are: (1) the cell suspension can be produced in most analytical laboratories without special microbial knowledge, (2) cell wall bound enzyme has a longer stability than isolated enzyme, and (3) cell production is much easier and cheaper than production of isolated enzymes.