New possibilities of dimethylformamide dimethylacetal as derivatization agent for gas chromatography/mas spectrometry analysis
T13N1
I.G. Zenkevich, T.I. Pushkareva
It is shown that the use of dimethylformamide dimethylacetal for derivatization of analytes in gas chromatography/mass spectrometry cannot be restricted by the known conversion of carboxylic acids, phenols, and thiols into their methyl esters (ethers), as well as the conversion of non-volatile amino acids (and C-amino compounds of other classes) into their dimethylaminomethylene derivatives. The application of this reagent in derivatization of hydrazine derivatives and volatile carbonyl-containing analytes is considered. In the last case the reaction takes place selectively at the expense of CH2 and/or CH3 groups in α-position to the carbonyl fragment. The principal predestination of derivatization of such analytes is their characteristics by differences of gas chromatographic retention indices (∆RI) of reaction products and initial substrates. The ranges of variations of such increments ∆RI appeared to be various for different sub-groups of carbonyl compounds; it permits us to define their structures more precisely. The mass spectra of C-dimethylaminomethylene derivatives of some carbonyl compounds, preferably 2-substituted 1-methyl- and 1-aryl-3-(dimethylamino)prop-2-en-1-ones, revealed intense
M – 17 peaks. The appearance of these signals can be explained by a hydrogen atom migration and formation of the [М – ОН]+ ions.