A gas chromatograph for quantification of peroxycarboxylic nitric anhydrides calibrated by thermal dissociation cavity ring-down spectroscopy

Abstract

Abstract. The peroxycarboxylic nitric anhydrides (PANs, molecular formula: RC(O)O 2 NO 2 ) can readily be observed by gas chromatography (PAN-GC) coupled to electron capture detection. Calibration of a PAN-GC remains a challenge, because the response factors differ for each of the PANs, and because their synthesis in sufficiently high purity is non-trivial, in particular for PANs containing unsaturated side chains. In this manuscript, a PAN-GC and its calibration using diffusion standards, whose output was quantified by blue diode laser thermal dissociation cavity ringdown spectroscopy (TD-CRDS), are described. The PAN-GC peak areas correlated linearly with total peroxy nitrate ( PN) mixing ratios measured by TD-CRDS (r > 0.96). Accurate determination of response factors required the concentrations of PAN impurities in the synthetic standards to be subtracted from PN. The PAN-GC and its TD-CRDS calibration method were deployed during ambient air measurement campaigns in Abbotsford, BC, from 20 July to 5 August 2012, and during the Fort McMurray Oil Sands Strategic Investigation of Local Sources (FOSSILS) campaign at the AMS13 ground site in Fort McKay, AB, from 10 August to 5 September 2013. The PAN-GC limits of detection for PAN, PPN, and MPAN during FOSSILS were 1, 2, and 3 pptv, respectively. For the Abbotsford data set, the PAN-GC mixing ratios were compared, and agreed with those determined in parallel by thermal dissociation chemical ionization mass spectrometry (TD-CIMS). Advantages and disadvantages of the PAN measurement techniques used in this work and the utility of TD-CRDS as a PAN-GC calibration method are discussed.

Low levels of nitryl chloride at ground level: nocturnal nitrogen oxides in the Lower Fraser Valley of British Columbia

“…inner diameter (ID) Teflon ™ inlet at a height of 4 m above ground; the setup is depicted in Fig. 3 of Tokarek et al (2014). A scroll pump whose flow rate was throttled using a 50 standard litres per minute (slpm) capacity mass flow controller was connected to the end of the common inlet to minimize the residence time of the sampled air and to reduce inlet "aging", i.e., accumulation of aerosol on filters of individual instruments, whose inlets tapped into the main inlet line at 90 • .…”

“…Further, the collisional dissociation chamber (CDC) was operated in declustering mode (−22.7 V) to break up ion clusters. Calibrations and matrix effect correction procedures and a time series of the PAN and PPN data were presented by Tokarek et al (2014 The CRDS used in this work was an amalgamated version of two instruments described earlier (Paul and Osthoff, 2010;Odame-Ankrah and Osthoff, 2011), called Improved Detection Instrument for Nitrogen Oxide Species (iDinos) (Odame-Ankrah, 2015). A schematic of the optical layout is shown in Fig.…”

“…An NO-O 3 chemiluminescence instrument (Thermo 42i) was used to monitor mixing ratios of NO and NO y , which was reduced to NO in a Mo converter heated to ∼ 320 • C placed outside a short distance (∼ 1 m) from the sample inlet. This instrument sampled from the main inlet via a Teflon ™ filter and filter holder and was calibrated daily against CRDS as described by Tokarek et al (2014). The slope uncertainty for each multipoint calibration was ±15 %.…”

“…This gas stream was periodically added to the main inlet with the aid of a normally open two-way valve connected to a vacuum pump in a similar fashion as described earlier for N 2 O 5 and PAN (Tokarek et al, 2014;Odame-Ankrah and Osthoff, 2011 (Wieser and Berglund, 2009) and our previously observed ratios of 0.315 ± 0.003 in Calgary and 0.3065 ± 0.0002 in Pasadena (Mielke et al, 2013). The reason(s) for these differences is unclear but they may be a result of fractionation processes (Koehler and Wassenaar, 2010;Volpe et al, 1998), a topic outside the scope of this paper.…”

Development of a photochemical source for the production and calibration of acyl peroxynitrate compounds

“…Furthermore, recent work suggests that synthesis of APN standards using acyl chloride compounds should be avoided for reasons of impurities (Tokarek et al, 2014); however, the use of a GC pre-separation step eliminates any possibility of unwanted measurement interferences.…”