Abstract
Abstract. A gas detection system has been developed, characterized, and deployed for pressurized gas-phase sample analyses and near-real-time online measurements. It consists of a cryogenic pre-concentrator (CryoTrap), a gas chromatograph (GC), and a new high-resolution atomic emission detector (AED III HR). Here the CryoTrap–GC–AED instrumental setup is presented, and the performance for iodine (1635 ± 135 counts I atom−1 pptv−1), sulfur (409 ± 57 counts S atom−1 pptv−1), carbon (636 ± 69 counts C atom−1 pptv−1), bromine (9.1 ± 1.8 counts Br atom−1 pptv−1), and nitrogen (28 ± 2 counts N atom−1 pptv−1) emission lines is reported and discussed. The limits of detection (LODs) are in the low parts per trillion by volume range (0.5–9.7 pptv), and the signal is linear to at least 4 orders of magnitude, which makes it a suitable method for diverse volatile organic compound (VOC) measurements in the atmosphere, even in remote unpolluted regions. The new system was utilized in a field study in a boreal forest at Hyytiälä, Finland, in late summer 2016, which made monoterpene measurements possible among other VOCs. Furthermore, pressurized global whole-air samples, collected on board the Lufthansa Airbus A340-600 IAGOS–CARIBIC aircraft in the upper troposphere and lower stratosphere region, were measured with the new setup, providing data for many VOCs, including the long-lived organosulfur compound carbonyl sulfide.
Highlights
Atomic spectrometric analysis has been reported to provide highly sensitive detection, a linear response of at least 5 orders of magnitude (> 105), and accurate elemental composition data of samples
In contrast to the alternative analytical approach of gas chromatography coupled to mass spectrometry (GC– MS), the atomic emission detector (AED) has the advantage of having highly selective wavelength-dependent element-specific detection and linear in-detector response
Karu et al.: CryoTrap–GC–AED for atmospheric trace gas measurements said, it is important to keep in mind that a detector is often the last step in the whole analytical instrumental setup; the response factor (RF) reflects the entire analyte pathway from the sample inlet to the detector signal recording
Summary
Atomic spectrometric analysis has been reported to provide highly sensitive detection, a linear response of at least 5 orders of magnitude (> 105), and accurate elemental composition data of samples. Karu et al.: CryoTrap–GC–AED for atmospheric trace gas measurements said, it is important to keep in mind that a detector is often the last step in the whole analytical instrumental setup; the response factor (RF) reflects the entire analyte pathway from the sample inlet to the detector signal recording This means that analyte losses by adsorption and absorption effects taking place in the transfer lines, pre-concentration stages, GC column, and the detector flow paths contribute to the final RF. If such an equimolar response for the entire analytical system can be achieved, this would greatly simplify the calibration of complex mixtures and would even allow quantification of unidentified compounds not present in a calibration standard. The calibration linearities, limits of detection, and compound-specific response factors are reported for 64 compounds
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