A new membrane inlet interface of a vacuum ultraviolet lamp ionization miniature mass spectrometer for on‐line rapid measurement of volatile organic compounds in air

Abstract

A novel membrane inlet interface coupled to a single-photon ionization (SPI) miniature time-of-flight mass spectrometer has been developed for on-line rapid measurement of volatile organic compounds (VOCs). The vacuum ultraviolet (VUV) light source for SPI was a commercial krypton discharge lamp with photon energy of 10.6 eV and photon flux of 10(10) photons/s. The experimental results showed that the sensitivity was 5 times as high as obtained with the traditional membrane inlet. The enrichment efficiency could be adjusted in the range of 10 to 20 times for different VOCs when a buffer cell was added to the inlet interface, and the memory effect was effectively eliminated. A detection limit as low as 25 parts-per-billion by volume (ppbv) for benzene has been achieved, with a linear dynamic range of three orders of magnitude. The rise times were 6 s, 10 s and 15 s for benzene, toluene and p-xylene, respectively, and the fall time was only 6 s for all of these compounds. The analytical capacity of this system was demonstrated by the on-line analysis of VOCs in single puff mainstream cigarette smoke, in which more than 50 compounds were detected in 2 s.

Membrane introduction system for trace analysis of volatile organic compounds using a single photon ionization time-of-flight mass spectrometer

“…Oh of tens of ppbv for toluene using a compact TOFMS with a conventional electron impact ion source [5]. Hou et al developed a membrane inlet interface coupled to a SPI-TOFMS with a krypton discharge lamp as an ionization source [16]. This achieved a detection limit as low as 25 ppbv for benzene.…”

“…MIMS has also been used for the analysis of liquid samples [17][18][19][20]. Silicone membranes in sheet type [3,6,[13][14][15][16] or hollow fiber type [12,[18][19][20][21] are typically used for the MIMS. Recently, membrane introduction systems coupled with an electron impact ion source time-of-flight mass spectrometer (TOFMS) have been developed to detect VOCs in air with detection limits less than ten parts per billion by volume (ppbv) [3,5].…”

“…The membrane selectively introduces the VOCs into the ionization source of a mass spectrometer, since the membrane has higher gas permeability for VOCs than for the main components of the atmosphere such as nitrogen and oxygen, as shown in Table 1. MIMS is widely used for the trace level detection of VOCs in environmental gaseous samples [3,5,6,[12][13][14][15][16]. MIMS has also been used for the analysis of liquid samples [17][18][19][20].…”

Development of a suitcase time‐of‐flight mass spectrometer for in situ fault diagnosis of SF6‐insulated switchgear by detection of decomposition products

“…Our group focused on the development of soft ionization methods for online mass spectrometry specifically based on a vacuum ultraviolet (VUV) lamp in recent years. We have successively designed a VUV lamp soft ionization source, [20] a photoelectron ionization source (PEI), [21] a magnetic field enhanced PEI, [22] a chemical ionization source with reactant O 2 + ions, [23] and a quasi ion trapping ion source for the online analysis of gaseous compounds. [24,25] In this paper, we demonstrate a TOFMS employing a compact-suitcase design to carry out all the key functions, namely, online sampling, photoelectron ionization, transfer of ions at different vacuum chamber, and mass analysis.…”

Vacuum Ultraviolet Lamp Based Magnetic Field Enhanced Photoelectron Ionization and Single Photon Ionization Source for Online Time-of-Flight Mass Spectrometry

“…The homemade oaTOFMS analyzer was reported in detail previously. 2,21 The electrons were generated by the photoelectric effect when VUV light irradiated on electrodes and consequently accelerated in electric field to the energy high enough to ionize molecules. The electron energy in the ionization process depended on the initial energy of electron ejected and energy obtained from the electric field.…”