Determination of Picomole Amounts of Choline and Acetylcholine in Blood by Gas Chromatography-mass Spectrometry Equipped with a Newly Improved Pyrolyzer

Blood levels of choline (Ch) and acetylcholine (ACh) have previously not been confirmed because of the difficulty in measuring these compounds. In this paper a recently developed method for the assay of Ch and ACh, which employs a chemical ionization (isobutane) quadrupole mass spectrometer (JEOL QH 100) equipped with a new type of pyrolyzer is reported. The correlation between the mass fragmentogram peak ratios and the amounts of compounds was good from 0.5 to 4 pmol. The assay limit for quantitation was ca. 0.3 pmol for Ch and ACh. The values for Ch from rat whole blood, serum and red blood cells were 10.88 +/- 1.46, 6.72 +/- 1.02 and 4.56 +/- 0.53 nmol/ml, respectively, and for ACh the respective values were 3.56 +/- 0.86, 1.69 +/- 0.16 and 1.87 +/- 0.83 nmol/ml. In human whole blood the levels of Ch and ACh were 22.55 +/- 3.97 and 3.23 +/- 0.23, respectively.