A dual-source miniature mass spectrometer with improved sensitivity

Previously, we have reported the development of a miniature mass spectrometer with a continuous atmospheric pressure interface, whose sensitivity was sacrificed due to the limited gas flow rate. In this study, a circular lens was designed and integrated on the ion transfer pathway between the two pumping stages, and a ten-fold sensitivity improvement could be achieved when coupling with external ionization sources. Besides the capability of working with ionization sources in the atmosphere, there is also an in-vacuum plasma ionization source, so that both volatile and non-volatile samples could be analyzed. A 10 ppbv detection sensitivity was achieved for dimethyl methyl phosphonate (DMMP) in air using the plasma ionization source. Furthermore, the miniature mass spectrometer was also demonstrated for the direct analyses of progesterone in drinking water and atrazine in soil samples using paper spray and syringe spray, respectively.