Direct Detection of Water-dissolved Ammonia Using Paper-based Analytical Devices

Abstract

A microfluidic paper-based analytical device (μPAD) is proposed for the selective detection of ammonia in water by using the modified Berthelot reagent and a fluidic channel consisting of hollow paper. The modified Berthelot reagents were uniformly dispersed in cyclohexane and then immobilized in a detection zone of the μPAD. The loading position of the reagents and the type of a sample flow channel were optimized to achieve a sensitive ammonia detection within a short analytical time. The NH3 μPAD exhibits a linear colorimetric response to the concentration of ammonia dissolved in water in the range of 1-100 mg L-1, and its limit-of-detection is 1.75 mg L-1. In addition, the colorimetric response was not influenced by the addition of 100 mg L-1 nitrogen containing compounds (sodium nitrate, sodium nitrite, uric acid, hydroxylamine, butylamine, diethylamine) or inorganic salts (NaCl, Na2HPO4), presenting the enough selectivity in the detection of water-dissolved ammonia against possible interferents. © 2023, Korean Sensors Society. All rights reserved.