Atmospheric Pressure Chemical Ionization (APCI) is a soft ionization technique commonly applied in Mass Spectrometry (MS) for analyzing non-polar and semi-polar compounds.
As a variant of Chemical Ionization (CI), APCI generates ions by chemical reactions in the gas phase, enabling the formation of both positive and negative ions.
Principle:
- A liquid sample is introduced into a heated nebulizer to create a fine mist of charged droplets.
- A corona discharge generates reagent ions (usually H3O+ or O2–) in the ionization region.
- The reagent ions react with the sample molecules in the gas phase through proton transfer or charge exchange.
- The resulting ions are detected by the mass spectrometer.
Advantages:
- Compatible with a wide range of compounds
- High sensitivity and low fragmentation
- Capable of ionizing both polar and non-polar compounds
Applications:
- Identification of organic compounds
- Drug metabolism studies
- Environmental analysis
- Food safety
Method Validation:
APCI methods are validated to ensure their accuracy, precision, and specificity. This typically involves:
- Establishing linearity and correlation coefficients
- Evaluating ion suppression and matrix effects
- Determining method detection and quantification limits