Analytical Instrument Documents


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Acquisitions of Molecular-weight Information Using Soft-ionization Techniques (PI and CI)

Electron ionization (EI), a hard-ionization technique that generates many fragment ions, is the most widely used ionization technique in gas chromatography–mass spectrometry (GC-MS). Since EI mass spectra have good reproducibility, qualitative analysis is possible by comparing an EI mass spectrum of a sample with that of the known compound recorded in the database. However, sometimes EI mass spectra lack molecular ions, which are of key importance to molecular-weight (MW) determination and correct compound assignment. Soft ionization is a useful way to determine MW. The JEOL JMS-Q1500GC offers two soft-ionization techniques: chemical ionization (CI) and photoionization (PI). In this application note, the MW information of diethyl phthalate and n-tetradecane were estimated from measurement results using both of these soft-ionization techniques.

Other Resources

The following resources are available for the JEOL Analytical Instruments:


Corona - Glow Discharge (DART Ion Source)

February 22, 2020