Determination of residual dimethylaminopropylamine in aminopropylamides of fatty acid using high-performance liquid chromatography

Abstract

A procedure for determination of the residual content of N,N-dimethyl-1,3-propanediamine (DMAPA) during synthesis of N,N-dimethylaminopropylamides of fatty acids (DMAPA FA) from coconut oil has been developed. The analysis was performed using high performance liquid chromatography on a Shimadzu LC-20 Prominence device equipped with a diode array detector and reversed phase column GL Sciences Inertsil ODS-3. Precolumn derivatization was carried out with a 13% — dansyl chloride (5-(dimethylamino)naphthalene-1-sulfonyl chloride) solution in acetone to increase the analyte response. The selected composition of the mobile phase — acetonitrile and triethylamine phosphate buffer solution (pH 3.0) in a volume ratio of 2:3 and optimized chromatographic conditions provided a clear peak of DMAPA with a retention time of 8.7 – 8.9 min. The proposed method provides determination of 0.02 – 10% DMAPA in DMAPAFA samples. Correctness of the procedure was confirmed in spike tests. The results obtained can be used for assessing the degree of conversion of starting materials in the synthesis of N,N-dimethylaminopropylamides of fatty acids, as well as for forecasting the content of N,N-dimethyl-1,3-propanediamine in the products on their base.