Sensitivity and intensity enhancement in open air mass spectrometry assisted with a continuous wave infrared laser

Abstract

To improve signal-to-noise ratios (SNRs) in open air mass spectrometry, a laser-assisted, direct-analysis-in-real-time (DART) mass spectrometer (LA-DART-MS) was developed by integrating a continuous wave (CW) infrared (IR) laser into an open air DART-MS. The CW IR laser (wavelength of 1070 nm) was used to assist the desorption of analytes and promote the reactivity of protonated water from the DART ion source. Using the LA-DART-MS, SNRs of Rhodamine 6G (R6G), urea, and testosterone were enhanced by factors of 31, 11, and 4, respectively, compared with the conventional DART-MS. The sensitivity enhancement was ascribed to the increased analyte concentration in air and activated protonated water induced by the IR laser irradiation.