Electrochemical Detection of Ammonia in Aqueous Solution Using Fluorescamine: A Comparison of Fluorometric Versus Voltammetric Analysis

En este estudio se comparan dos métodos diferentes para la determinación de amoníaco en soluciones acuosas; la espectroscopía de fluorescencia frente a un análisis voltamperométrico del amoníaco en solución acuosa en reacción con fluorescamina. se encontró que los límites de detección eran similares en ambos métodos.

Fluorescamine is a non-fluorescent reagent widely used for the quant. detn. o f primary amines by fluorescence spectroscopy as it reacts readily with primary amines to form a fluorescent product.  In this work, a new sensitive voltammetric method for the detection of ammonia in aq. soln. by the reaction with fluorescamine has been developed.  First, the electrochem. behavior of fluorescamine in the absence and presence o f ammonia was investigated in 0.1 mol·L-1 borate buffer soln. (pH 9.0) by cyclic voltammetry using a glassy carbon (GC) electrode.  As for fluorescamine itself, a well-defined irreversible oxidn. peak could be obsd. at ca. 0.70 V vs. SCE.  When ammonia was added to the fluorescamine soln., another irreversible oxditaion peak corresponding to the oxidn. o f the reaction product formed between fluorescamine and ammonia could be obsd. at ca. 0.46 V vs. SCE.  Upon the addn. of ammonia, the oxidn. peak o f fluorescamine became smaller while the oxidn. peak o f the reaction product formed increased in height, due to the stoichiometric chem. consumption o f fluorescamine by ammonia and the formation o f the product during the reaction, resp.  These two anodic peaks corresponding to the oxidn. of fluorescamine and its fluorescent product formed were then used for the quant. detection o f ammonia, explored by square wave voltammetry and by fluorescence spectroscopy.  The square wave voltammetric response o f the reaction product formed showed a linear response over ammonia concn. range o f 0 to 60 μmol-L-1.  The limits o f detection (LOD) was found to be 0.71 μmol·L-1 and 3.17 μmol-L-1 detd. based upon Signal/Noise (S/N) = 3 and 3cr, resp. These limits o f detection are similar to those obtained with the fluorometric method.

Panchompoo, Janjira; Compton, Richard G.

Dianhuaxue (2013), 18(5), 437-449