Simultaneous Determination of Ammonium Ion, MDEA, Common Metal Cations and Dialkyl Amines in Amine Processing Solution by Ion Chromatography

Abstract

In the present study a new method has been developed for the separation and estimation of common metal cations (Li+, Na+, K+), Methyl diethanolamine (MDEA) (and types of alkyl amines) and their degradation products including ammonium ion used in amine processing solution. The acid treating amines such as dimethyl amine (DMA), Diethyl amine (DEA), Dipropylamine (DPA), Diisopropyl amine (DPA) and Dibutyl amine (DBA) in amine processing solution have been separated by Ion Chromatography (IC) using conductivity detector in single column mode. Desired separation was achieved within 20 min using mixture of 3 mM CH3SO3H+CH3CN (90:10) as mobile phase on Dionex Ion Pac SCS1 column at temperature of 30°C. Calibration curve for all the cations (Li+, Na+, K+, NH4+) in the concentration range of 2.5-20 ppm and 3-100 ppm for dialkyl amine were plotted and it was observed that the correlation coefficient (R2) list in between 0.9980 and 1.0. Relative Standard Deviation (RSD) observed for all the abovementioned cations were in the range of 0.81-2.33%. Recovery of all the cations at different concentrations of amine processing matrix was in the range of 80-120%. The lower Limit of Detection (LOD) for Li+, Na+, K+, NH4+ was 0.5 ppm, and for MDEA and all above alkyl amines was 1.0 ppm. The operational simplicity of this method in terms of accuracy and precision can be a good alternative for the estimation of above ions in amine processing solution.