Which is the precise ionization and %area is close to absolute % between MS ionization (GCMS) and FID ionization (GCFID)? Why?

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Dr. Ajai Prakash Gupta

Ms ionization is a precise ionization. In MS 70 eV energy electrons used for ionization , which is sufficient enough to break most of the bonds. % area of many detectors may vary because all detectors are not suitable for all type of samples. FID is a universal detector but it is not suitable halogenated compounds eg pesticides, herbisides etc. Due to high sensitivity of MS detector it gives more number of peaks and % area distributed into total number of peaks. If number of peaks more % area less if number of peaks less peak area more.