| Popis: |
Mass spectrometer ion sources are normally located inside a high-vacuum envelope. An ion source operating at atmospheric pressure is better suited, it not essential, for a growing number of applications. MS analysis of samples pyrolyzed under controlled conditions makes use of chemical ionization at atmospheric pressure. On-line LC-MS which employs the heated pneumatic nebulizer interface together with atmospheric pressure chemical ionization is suitable for moderately polar samples that are not too labile. Highly polar, thermolabile, and ionic samples and biolpolymers require the application of electrospray ionization at atmospheric pressure combined with on-line separation by LC or CE. The determination of the molecular mass of proteins, nucleic acids and other (bio)polymers by electrospray ionization has accelerated the formerly slow development of atmospheric pressure ionization. In recent years the atmospheric pressure ionization souce has been transformed from am exotic research instrument into a standard tool for problems in (bio)chemistry, pharmacy and biotechnology. |
