Journal of Chromatography A, 1266 (2012) 110–115 Contents lists available at SciVerse ScienceDirect Journal of Chromatography A j our na l ho me p ag e: www.elsevier.com/locate/chroma Direct and simultaneous determination of trace-level carbon tetrachloride, peroxyacetyl nitrate, and peroxypropionyl nitrate using gas chromatography-electron capture detection Gen Zhang a , Yujing Mu a,∗ , Junfeng Liu a , Abdelwahid Mellouki b,∗∗ a Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China b Centre National de Recherche Scientifique-Institut de Combustion, Aérothermique, Réactivité et Environnement (CNRS-ICARE) and OSUC, 45071 Orléans Cedex 02, France a r t i c l e i n f o Article history: Received 5 July 2012 Received in revised form 21 September 2012 Accepted 24 September 2012 Available online 2 October 2012 Key words: Peroxyacetyl nitrate Peroxypropionyl nitrate Capillary column GC-ECD Detection a b s t r a c t Gas chromatography equipped with electron capture detector (GC-ECD) has been widely used for detec- ting atmospheric peroxyacetyl nitrate (PAN) and peroxypropionyl nitrate (PPN). However, to the best of our knowledge, only a few capillary columns have been adopted for separation to achieve the direct and simultaneous analysis of the two atmospheric pollutants. This paper demonstrates a novel method for directly and simultaneously measuring atmospheric carbon tetrachloride (CCl 4 ), PAN, and PPN using GC-ECD with a DB-1 separation column. The responses of the GC-ECD to PAN, PPN, and CCl 4 were indi- vidually calibrated by using gas mixtures prepared via volatilization of synthesized solutions of PAN and PPN or high-purity CCl 4 reagent in a Teflon Bag. The concentrations of PAN and PPN in the synthesized solutions were quantified by ion chromatography (IC). Further calibration of the GC-ECD for PAN was conducted by in situ photochemical formation of gaseous PAN which was quantified by a NO x analyzer. The two calibration methods agreed well with each other, and the overall uncertainties for measuring atmospheric PAN were estimated to be ±13% and ±15% based on the calibrations of IC and NO x , respec- tively. The detection limits (three times the signal to noise ratio) for PAN, PPN, and CCl 4 were estimated to be 22, 36, and 5 pptv (parts per trillion by volume), respectively. The atmospheric concentrations of these compounds were measured for several days in August in Beijing, and the values obtained in this study were found to be in good agreement with the data reported in the literature for Beijing using other GC-ECD methods. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Peroxyacetyl nitrate (PAN) and its homologues (thereafter referred to PANs, RC(O)OONO 2 ) are particularly important sec- ondary pollutants formed from photochemical reactions of volatile organic compounds (VOCs) in the presence of NO x [1–4]. These compounds are thermally unstable in the lower troposphere, but are quite stable in the mid- and upper troposphere and can be trans- ported over long distances from the polluted continental regions into the remote troposphere [5]. PAN has been recognized as the most abundant species among PANs. The thermal decomposition of PAN is the primary tropospheric loss process at up to approximately 7 km, above which the photolysis reaction becomes important [6,7]. Singh and Hanst [4] have suggested that PAN acts as a temporary ∗ Corresponding author. Tel.: +86 10 62849125; fax: +86 10 62849117. ∗∗ Corresponding author. Tel.: +33 238 25 76 12; fax: +33 238 69 60 04. E-mail addresses: yjmu@rcees.ac.cn (Y. Mu), mellouki@cnrs-orleans.fr (A. Mellouki). reservoir for NO x through the long-range transport and subsequent release of NO x , especially in the lower troposphere where it may control the photochemical production of O 3 in the remote marine troposphere. PANs have been also recognized as lachrymators [8], mutagens [9], and phytotoxins [10]. Carbon tetrachloride (CCl 4 ), the other species investigated in this work, was often used during the synthesis of chlorofluorocar- bons and has been widely used as a solvent for the past chemical processes [11]. Compared to PANs, CCl 4 is thermally stable in the troposphere, not subject to photolysis in the troposphere and non- reactive toward the tropospheric oxidants [12]. The lifetime of atmospheric CCl 4 extends to several decades [13]. Therefore, the emitted CCl 4 can ultimately diffuse into the stratosphere, where it will release Cl atoms under the intensive ultraviolet sunlight irra- diation and participate in the depletion of the stratospheric ozone [14]. The atmospheric pollution levels of PAN, peroxypropionyl nitrate (PPN), and CCl 4 are of key concern and are of partic- ular importance in atmospheric chemistry. Several techniques have been developed for measuring these species in the 0021-9673/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.chroma.2012.09.092