Dimethylethanolamine (DMAE) can be determined by several methods including:

Titration: DMAE can be titrated with a strong base such as sodium hydroxide to determine its concentration.
Spectrophotometry: DMAE can be measured spectrophotometrically by measuring its absorbance at 254 nm.
Gas chromatography: DMAE can be separated and quantified by gas chromatography.
High performance liquid chromatography: DMAE can be separated and quantified by high performance liquid chromatography.
The method used to determine DMAE will depend on the concentration of DMAE in the sample and the level of accuracy required.