An Amperometric Biosensor Based on Alanine Dehydrogenase for the Determination of Low Level of Ammonium Ion in Water

Abstract

An amperometric electrochemical biosensor has been developed for ammonium (NH4+) ion detection by immobilising alanine dehydrogenase (AlaDH) enzyme in a photocurable methacrylic membrane made up of poly(2-hydroxyethyl methacrylate) (pHEMA) on a screen-printed carbon paste electrode (SPE). The current detected was based on the electrocatalytic oxidation of nicotinamide adenine dinucleotide reduced (NADH) that is proportional to the consumption ofNH4+ion whilst enzymatic amination of AlaDH and pyruvate is taking place. The biosensor was operated amperometrically at a potential of +0.6 V and optimum pH 7. TheNH4+biosensor demonstrated linear response toNH4+ion concentration in the range of 0.03–1.02 mg/L with a limit of detection (LOD) of 8.52 μg/L. The proposed method has been successfully applied to the determination ofNH4+ion in river water samples without any pretreatment. The levels of possible interferents in the waters were negligible to cause any interference on the proposed method. The analytical performance of the biosensor was comparable to the colorimetric method using Nesslerisation but with much lower detection limit and linear response range at ppb level.

Fast responsive, optical trace level ammonia sensor for environmental monitoring

“…It is not only present in substances like refrigerants, household cleaners, and (most abundantly) industrial fertilizers, but is also produced in nature by all animal cells [1] resulting from degradation of amino acids [2], food putrefaction [3], excretion, and decomposition of waste and sewage. Due to this broad use and existence of ammonia it can be found in the atmosphere [4], the soil [5], as well as in river- [6] and seawater [7]. Furthermore ammonia is toxic to any kind of animals, from microorganisms [8] to more differentiated life forms [9].…”

“…Many different methods have been employed for analytical detection of ammonia, such as flow spectrometrics [12], potentiometric electrodes [13], IR absorption [14], amperometric [6] and conductivity [15] measurements, or spectrophotometric approaches based on the Berthelot reaction [16] or on Nessler’s method [12]. However, these methods consume chemicals, need batch separation from the analytical sample, or require sample pretreatment and/ or expensive instrumentation, which prevent these approaches being applied for continuous and simple monitoring tasks.…”

Trace Ammonia Sensors Based on Fluorescent Near-Infrared-Emitting aza-BODIPY Dyes

“…Many different methods have been developed for analytical detection of dissolved ammonia and have been mainly based on electrochemical or optical transduction. Electrochemical methods including potentiometric, amperometric, or conductometric techniques have high selectivity, detection limits in the ppm range, and fast response time, but drawbacks still exist regarding cross-sensitivity to salinity, , signal drift, and miniaturization of the reference electrode . NH 3 detection employing colorimetric approaches, mostly based on Nessler’s reaction or Berthelot’s indophenol method, , is established in routine analysis.…”

An efficient colorimetric inspection of ammonia using silver nanoparticles synthesized by 3‐(1‐(2‐(2,4‐dinitrophenyl)hydrazono)ethyl)‐1H‐indole as chemo‐sensors in water environment

“…[ 26 ] It is broadly employed in numerous industries, that is, fertilizers and cooling systems, dye production, medicine, plant and meat cooling, and explosives. [ 27–30 ] Ammonia poses serious health risks owing to its poisoning, and it is harmful to all animals. [ 26,31,32 ] The measurement of ammonia in body has medical implications, since it provide an indicator of illness or disease.…”