An ultrasensitive SPI/PAI ion source based on a high-flux VUV lamp and its applications for the online mass spectrometric detection of sub-pptv sulfur ethers

Single-photon ionization mass spectrometry (SPI-MS) is an attractive analytical technique for the online detection of volatile organic compounds; however, the low photon flux of the vacuum ultraviolet (VUV) lamp commonly used in the SPI ion source and the corresponding low detection sensitivity remain a constraint to its wide field applications. In this study, a new VUV lamp-based SPI ion source was developed. By increasing the discharging volume and optimizing the configuration of the lens and ionizer, the photon flux of the VUV lamp and the sensitivity of the ion source were significantly improved. The VUV lamp output was 2.8 × 10