The Power of Exact Mass Measurement: An Example of Unknown Compound Identification
Recently, JEOL introduced the AccuTOF-GC, an innovative GC/time-of-flight mass spectrometer (TOF MS) that is capable of both high data acquisition rates and easy exact mass measurements. The exact mass measurements can then be used to generate lists of possible elemental compositions, which is a powerful tool for identifying unknown compounds. Additionally, this information can be combined with the fragmentation information to help confirm the identity an unknown compound.
In this work, the AccuTOF-GC system was used to identify an unknown compound in a liquid crystal extract.
The system used for this work was the JEOL AccuTOF-GC TOF MS. Liquid crystal from a pocket calculator display was dissolved in hexane. Afterwards, the sample was injected onto a DB-5 GC column (0.18mm x 10m, 0.18μm film thickness). The oven temperature was held at 40°C for 1 min and then increased to 300°C at 50°C/min rate. The TOF MS was tuned to achieve a resolution of 5,000 (FWHM) at m/z 293 (Perfluorokerosene). 2,4,6-tris(trifluoromethyl)-1,3,5-triazine was used as an internal standard for the exact mass measurements in both EI and CI modes. The CI reagent gas was isobutane. The NIST mass spectral database (2002) was used for the EI spectrum searches.