Mass-spectrometric determination of metal chelates

A method has been developed for the determination of copper as copper acetylacetonate using electron-impact mass spectrometry with electrical detection. The use of completely deuterated copper acetylacetonate as an internal standard allows a simple and rapid determination. As might be expected, ligand exchange appears to occur, however without interfering effect. The determination is performed by comparing corresponding peak intensities of unknown and reference compounds. The accuracy and reproducibility in the nanogram range are about 3%. The method can be easily extended to the determination of other metals according to the same principle.