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

Abstract

International audienceTo 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

Advances in Ionization for Mass Spectrometry

“…Ultimately, these authors achieved their goal by introducing several modifications to the DART source and sample gap. Lu et al improved ionization efficiency of three analytes by incorporating a continuous wave (CW) IR laser in their DART ion source . Combining DART and laser desorption, CW-LA-DART-MS yielded significantly stronger signal-to-noise than using DART-MS alone.…”

Laser Desorption/Ablation Postionization Mass Spectrometry: Recent Progress in Bioanalytical Applications

“…There has not been a uniform term for this kind of postionization method. Techniques employing DART or analogous ion sources based on corona discharge are named as IR‐LAMICI, ambient SALDI, plasma‐assisted multiwavelength laser desorption ionization (PAMLDI) or plasma‐assisted laser desorption ionization (PALDI), LD‐CBI, and LA‐DART, successively (Galhena et al, 2010; Zhang et al, 2012a; Chang et al, 2013; Lu et al, 2015; Wang et al, 2018).…”

“…New approaches using laser with different wavelength and pulse mode continues to appear. Lu et al (2015) improved DART‐MS detection of small organic molecules by combining a CW 1070 nm laser with DART. The dual function of the IR laser in augmenting the analyte population in the air and enhancing the reactivity of protonated water clusters from the DART source enabled the extension of LOD of rhodamine 6 G by two orders of magnitude.…”

Isotope signature characterization of Pb and U in open air by laser-ablation mass spectrometry

“…7,11,24,[26][27][28][29][30][31][32] With the rapid advance of ambient ionizing techniques, such as desorption electrospray ionization and direct analysis in real time, ambient MS has received tremendous attention and experienced considerable progress in recent years. [33][34][35] Compared to traditional MS, ambient MS minimizes the sample pretreatments and offers unprecedented flexibility in real-time and in situ analyses. [33][34][35] Laser ablation has been demonstrated to be effective in atomizing and ionizing almost all materials and is, therefore, frequently used in ambient MS. [33][34][35] However, due to the light-isotope-enrichment effect in laser-ablated plasma plumes [36][37] and complicated matrix effects in ambient atmospheres, accurate isotope-signature analyses are extremely challenging.…”

“…[33][34][35] Compared to traditional MS, ambient MS minimizes the sample pretreatments and offers unprecedented flexibility in real-time and in situ analyses. [33][34][35] Laser ablation has been demonstrated to be effective in atomizing and ionizing almost all materials and is, therefore, frequently used in ambient MS. [33][34][35] However, due to the light-isotope-enrichment effect in laser-ablated plasma plumes [36][37] and complicated matrix effects in ambient atmospheres, accurate isotope-signature analyses are extremely challenging.…”