Miniaturized high-performance drift tube ion mobility spectrometer

Abstract

Developing powerful hand-held drift tube ion mobility spectrometers (IMS) requires small, lightweight drift tubes with high analytical performance. In this work, we present an easy-to-manufacture, miniaturized drift tube ion mobility spectrometer, which is manufactured from polyether ether ketone, stainless steel foils and printed circuit boards. It is possible to operate the drift tube IMS with a radioactive 3 H ionization source or a non-radioactive X-ray ionization source with 3 kVacceleration voltage. The drift tube design provides high resolving power of R p = 63 at a drift length of just 40 mm, 15 mm × 15 mm in cross-section (outer dimensions) and a drift voltage of 2.5 kV. The limits of detection for less than one second of averaging are 40 ppt v for dimethylmethylphosphonate and 30 ppt v for methyl salicylate. For demonstration, the miniaturized drift tube IMS is integrated into a stand-alone battery-powered mobile device, including a closed gas-loop, high performance driver electronics and wireless data transmission. In a proof-of-concept study, this device was tested in an international field evaluation exercise to detect the release of a volatile, hazardous substance inside a large entry hall.

Towards a hand-held, fast, and sensitive gas chromatograph-ion mobility spectrometer for detecting volatile compounds

“…Retention times, reduced ion mobilities and detection limits of all investigated substances are listed in Table 2. Regarding the differences in detection limits when comparing stand-alone IMS [24] and GC-IMS, the following aspects should be kept in mind besides dilution effects due to peak broadening. Dilution effects in fittings and in the IMS reaction region, although the reaction region was kept at a minimum.…”

“…The volume of the reaction region of the IMS is just 160 μL keeping the GC resolving power. The IMS used in this work has been basically described elsewhere [24]. Limits of detection have been determined in the range of ppt v within averaging times of 1 s. Outer overall dimensions are only 15 mm × 15 mm × 56 mm.…”

“…Limits of detection have been determined in the range of ppt v within averaging times of 1 s. Outer overall dimensions are only 15 mm × 15 mm × 56 mm. A slight modification to the design described in [24] has been made by adding a second waste capillary ( Fig. 1, orange line, GC carrier gas out) directly connected to the reaction chamber to obtain better purging of this region.…”

“…3. This small and light weight design is easy-to-integrate into the closed-loop IMS demonstrator described in [24]. In this context, it needs to be mentioned that this demonstrator and in particular the periphery (filters, pumps, electronics, battery, etc.)…”

P2.03 - Bundled column GC-IMS – a miniaturized system for fast and sensitive on-site analytics

“…For ionization, a 130 MBq tritium source is used in this work. However, other non-radioactive sources can be easily used [13]. Once the ions are injected in the drift region by a field switching shutter [14], they are moving along the drift tube, driven by an electrical field.…”