Gas chromatography mass spectrometry analysis of polyamines using deuterated analogs as internal standards

Abstract

Quantitative analyses of subnanomole quantities of the polyamines putrescine, cadaverine, spermidine and spermine by the gas chromatography mass spectrometry technique of selected ion monitoring are complicated by effects of the chromatographic column. These effects include sample retention by the column and chromatographic band broadening, and are sufficiently serious that spermine (as the trifluoroacetylated derivative) was not detectable at levels below 50 picomoles. Because the chromatographic behaviors of the four polyamines vary, quantiative analysis using a single internal standard is not feasible. The deuterated polyamine analogs, putrescine-2H4, cadaverine-2H4, spermidine-2H6 and spermine-2H8, have been synthesized and used to accomplish quantiative analyses of the corresponding isotopically natural abundance polyamines to the one picomole level. This enhancement in analytical sensitivity is accomplished by use of large excesses (greater than or equal to 100 picomoles) of the deuterated analogs to improve chromatographic band profiles. The use of such large molar excesses of deuterated analogs for selected ion monitoring analyses is possible because their electron impact spectra exhibit high mass ions ([M-F3C]+, [M-F3CCO]+) which possess greater than or equal to 4 deuterium atoms and have intensity ratios (I2H(max):IH) of 500 or greater.