Direct mass spectrometry analysis of untreated samples of ultralow amounts using extraction nano-electrospray

Direct mass spectrometry analysis of untreated samples of volumes as low as 0.2 mu L was achieved using fast extraction and nanoESI (electrospray ionization) in a combined fashion. The analytes in dried samples on paper substrates were extracted by an organic solvent in a nanoESI tube and ionized with a high voltage applied for generating a spray. The ionization source produced stable signals for different atmospheric pressure interfaces of triple quadrupole instruments. Analysis times more than 20 minutes were available with 10 mu L solvent consumed for the entire analysis process. The performance in qualitative and quantitative analyses was characterized with a wide variety of samples. Limits of detection as low as 0.1 ng mL(-1) (corresponding to an absolute amount of 0.05 pg) were obtained for analysis of atrazine in river water, thiabendazole in orange homogenate, and methamphetamine in blood.