Patent ID: 8728824

Claim:
A method for determining an amount of one or more very long chain fatty acids (VLCFA) and/or branched chain fatty acids (BCFA) in a sample by mass spectrometry, the method comprising: (a) subjecting the sample to an atmospheric pressure chemical ionization (APCI) source to generate one or more VLCFA and/or BCFA ions detectable by mass spectrometry; (b) determining the amount of the one or more VLCFA and/or BCFA ions by mass spectrometry; and (c) relating the amount of the one or more VLCFA and/or BCFA ions determined in step (b) to the amount of the VLCFA and/or BCFA in the sample; wherein the VLCFA and/or BCFA are underivatized prior to ionization.