Technical Note: Intercomparison of formaldehyde measurements at the atmosphere simulation chamber SAPHIR

Abstract

Abstract. The atmosphere simulation chamber SAPHIR at the Research Centre Jülich was used to test the suitability of state-of-the-art analytical instruments for the measurement of gas-phase formaldehyde (HCHO) in air. Five analyzers based on four different sensing principles were deployed: a differential optical absorption spectrometer (DOAS), cartridges for 2,4-dinitrophenylhydrazine (DNPH) derivatization followed by off-line high pressure liquid chromatography (HPLC) analysis, two different types of commercially available wet chemical sensors based on Hantzsch fluorimetry, and a proton-transfer-reaction mass spectrometer (PTR-MS). A new optimized mode of operation was used for the PTR-MS instrument which significantly enhanced its performance for online HCHO detection at low absolute humidities.The instruments were challenged with typical ambient levels of HCHO ranging from zero to several ppb. Synthetic air of high purity and particulate-filtered ambient air were used as sample matrices in the atmosphere simulation chamber onto which HCHO was spiked under varying levels of humidity and ozone. Measurements were compared to mixing ratios calculated from the chamber volume and the known amount of HCHO injected into the chamber; measurements were also compared between the different instruments. The formal and blind intercomparison exercise was conducted Correspondence to: T. Brauers (th.brauers@fz-juelich.de) under the control of an independent referee. A number of analytical problems associated with the experimental set-up and with individual instruments were identified, the overall agreement between the methods was fair.

Measuring OVOCs and VOCs by PTR-MS in an urban roadside microenvironment of Hong Kong: relative humidity and temperature dependence, and field intercomparisons

“…Moreover, it is easy to measure RH and T of ambient air for further correction of HCHO data by PTR-MS in practice. Wisthaler et al (2008) reported the intercomparison between PTR-MS and DNPH-HPLC in an atmosphere simulation chamber; good agreement was found between PTR-MS and DNPH-HPLC while ambient air was introduced into the chamber, but the concentration of HCHO measured by DNPH-HPLC was less than that by PTR-MS, which could be caused by some interferences for the DNPH-HPLC method or the varying performance of the KI ozone scrubber. Overestimation of DNPH-HPLC for HCHO in the presence of NO 2 was also reported by Herrington and Hays (2012), because NO can be oxidized to NO 2 in the upstream ozone scrubber, and NO 2 will react with DNPH to form 2,4-dinitrophenyl azide (DNPA), which has similar chromatographic properties to the formaldehyde-DNP-hydrazone.…”

“…Good agreement was found between PTR-MS and DOAS in both moun- tain areas (slope = 1.01) (Inomata et al, 2008) and urban areas (slope = 1.17) (Warneke et al, 2011b). HCHO measurement by DNPH-HPLC was compared to PTR-MS in an atmosphere simulation chamber by Wisthaler et al (2008), and significant lower HCHO levels by DNPH-HPLC were observed in dry synthetic air because of hydrazine-to-hydrazone conversion. Proton-transfer-reaction mass-spectrometry (PIT-MS), atmospheric pressure chemical ionization mass spectrometry (AP-CIMS), and GC- MS/FID were chosen as alternative monitoring methods for acetaldehyde, acetone, and MEK.…”

“…Lau et al (2010) found that 31-48 % of ambient VOCs in Hong Kong were generated by vehicle-and marine-vessel-related sources in [2002][2003], and the percentage increased to 40-54 % in 2006-2007. In order to investigate urban roadside VOCs in Hong Kong, multiple sampling and analytical techniques were used, such as offline 2,4-dinitrophenylhydrazine (DNPH) cartridge sampling followed by high-performance liquid chromatography (HPLC) analysis for oxygenated volatile organic compounds (OVOCs); online gas chromatography (GC) with flame ionization detection (FID); and offline canister sampling followed by GC with mass spectrometer detection (MSD), FID, and electron capture detection (ECD) for VOCs Cheng et al, 2014;Ou et al, 2015). These techniques, however, can be impacted by their relatively low sampling resolution that may lead to the underestimation or overestimation of ambient OVOC and VOC concentration levels (Wisthaler et al, 2008;Jobson et al, 2010;Wang et al, 2014). Moreover, since there is no single technique that can measure all OVOCs and VOCs simultaneously, different kinds of sampling and analytical techniques are usually used to obtain the measurements of these species (Wisthaler et al, 2008;Ambrose et al, 2010;Jobson et al, 2010;Warneke et al, 2011a).…”

“…These techniques, however, can be impacted by their relatively low sampling resolution that may lead to the underestimation or overestimation of ambient OVOC and VOC concentration levels (Wisthaler et al, 2008;Jobson et al, 2010;Wang et al, 2014). Moreover, since there is no single technique that can measure all OVOCs and VOCs simultaneously, different kinds of sampling and analytical techniques are usually used to obtain the measurements of these species (Wisthaler et al, 2008;Ambrose et al, 2010;Jobson et al, 2010;Warneke et al, 2011a).…”

PTR-QMS versus PTR-TOF comparison in a region with oil and natural gas extraction industry in the Uintah Basin in 2013

“…The instrument has been described and characterized in great detail over the last several years (Blake et al, 2009;de Gouw and Warneke, 2007;Hansel et al, 1995Hansel et al, , 1999Lindinger et al, 1998a, b;Warneke et al, 2001Warneke et al, , 2003Warneke et al, , 2011b and many successful intercomparisons with other techniques such as gas chromatography mass spectrometry (GC-MS) have demonstrated the sensitivity and the selectivity of PTR-QMS de Gouw and Warneke, 2007;Haase et al, 2012;Wisthaler et al, 2008). PTR-QMS is a chemical ionization mass spectrometry technique that detects VOCs using proton transfer reactions with H 3 O + , but has the drawback that only the nominal unitresolution mass of one VOC at a time can be determined.…”