Coupling laser desorption with corona beam ionization for ambient mass spectrometric analysis of solution and powder samples.

An infrared (940nm) laser desorption coupled with corona beam ionization (LD-CBI) technique was developed for expanding the application of the ambient mass spectrometry (AMS). A black ceramic sample plate was employed to facilitate the non-resonance absorption of laser energy. Solution and powder samples were immobilized in the shallow depression on ceramic plate and desorbed precisely since there was not gas disturbing. The dimer ion (m/z 1216.51) of reserpine was detected without any matrix assistance. In comparison with similar APCI-related ambient technique, the upper mass rang of analyte was broadened significantly. The feasibility of LD-CBI approach was demonstrated with 10 model pesticides. Typically, the limit of detection (LOD) of Malathion was as low as 6pg in the selected reaction monitoring (SRM) mode. The value is 166 times lower than the results from preceding technique desorption corona beam ionization (DCBI). As an APCI related ambient desorption ionization approach, LD-CBI technique could be a well complementary tool for direct detection of solution and powder samples.