Rapid on-chip quantification of ammonia nitrogen based on a ‘flow and react’ mechanism

Abstract

ABSTRACT Ammonia nitrogen pollution comes from a variety of sources, resulting in a wide distribution of concentrations and forms of existence across different samples. The on-site rapid detection of ammonia nitrogen in water is of great importance especially in unexpected water pollution accidents. In this paper, an inexpensive and portable microfluidic chip for the quantitative detection of ammonia nitrogen in water was developed. Solid reagents specific to ammonia nitrogen was pre-loaded in the microchannels and then liquid sample was introduced to initiate reactions that generated optical signals. A novel ‘flow and react’ regime replying on accelerated dissolution and reaction was proposed, shortening reaction time and reducing reagent dosage significantly. Ammonia nitrogen concentration in the range of 0.3–10 ppm was determined successfully within 5 min with this chip and a fibre spectrophotometer.