Ionization of Organic Compounds Affected by Laser Plasma Radiation at Atmospheric Pressure

The results of a study of the pathways of ion formation from organic compounds in Atmospheric Pressure Laser Plasma Ionization (APLPI) are presented. The instrumental implementation of the method is based on its combination with a high-resolution mass analyzer. Solid dosage forms and also physiologically active compounds were studied. It was found that the main pathways leading to the formation of positively charged ions are the following: protonation; addition of ammonium, synthesized in the ion source; and photoionization. In the negative ionization mode, deprotonated molecules, anion adduct ions, and molecular ions are formed. In both modes, ions formed as a result of the preliminary oxidation of analyte molecules in the ion source and their subsequent ionization were detected. A possibility of using the APLPI for the rapid analysis of pharmaceutical drugs without sample preparation is demonstrated.