Separation of sarcosine and L-alanine isomers using corona discharge ion mobility spectrometry

The capability of corona discharge ion mobility spectrometry (CD-IMS) for separation and quantification of sarcosine and L-alanine isomers has been evaluated for the first time. Although these two compounds have the same mass and m/z values in mass spectrometer, ion mobility spectrometry was able to separate and determine them. Variables including carrier gas flow rate, injection and cell temperatures were optimized. The reduced mobilities (K ₀) of sarcosine and L-alanine were 1.96 and 1.83, respectively, based on the reduced mobility of nicotinamide. At the optimized conditions the detection limit of sarcosine and L-alanine were 0.7 and 0.9 μg/mL, respectively. The relative standard deviation (RSD) was found to be 6%. Furthermore, a sample injection port of a gas chromatograph was also modified to introduce solvent-free samples into the IMS.