Determination of diethanolamine and N-nitrosodiethanolamine in fatty acid diethanolamides

Diethanolamine (DEA) is a precursor of N-nitrosodiethanolamine (NDELA), an animal carcinogen. A gas chromatographic (GC) method was developed for determining DEA in fatty acid diethanolamides that are commonly used in cosmetic products. Methanolic solutions of the amides were analyzed by GC with flame ionization detection on either a wide-bore methyl silicone (Rt(x)-1) or 95% dimethyl-5% diphenyl polysiloxane (SPB-5) capillary column. Recovery of DEA from fatty acid dialkanolamides at fortification levels of 0.50, 1.00, and 5.00% ranged from 94 to 100%, In a survey of commercial fatty acid diethanolamides, DEA was found at levels ranging from 1.1 to 14.0%, and most were in good agreement with manufacturer's DEA specifications. Fatty acid diethanolamides also were analyzed for NDELA by liquid chromatography interfaced to a thermal energy analyzer. Recovery of NDELA from fatty acid diethanolamides at fortification levels of 50, 100, and 200 ppb averaged 95%, No NDELA was found in any of the fatty acid diethanolamide samples analyzed.