ORIGINAL PAPER Comparison of quartz and Teflon filters for simultaneous collection of size-separated ultrafine aerosol particles and gas-phase zero samples Jevgeni Parshintsev & Jose Ruiz-Jimenez & Tuukka Petäjä & Kari Hartonen & Markku Kulmala & Marja-Liisa Riekkola Received: 3 March 2011 /Revised: 15 April 2011 /Accepted: 18 April 2011 /Published online: 1 May 2011 # Springer-Verlag 2011 Abstract In this research, the two most common filter media, quartz and Teflon, were tested to obtain information about the possible adsorption of gas-phase compounds onto filters during long sample collection of atmospheric aerosols. Particles of nanometer-size for off-line chemical characterization were collected using a recently introduced differential mobility analyzer for size separation. Samples were collected at an urban site (Helsinki, SMEARIII station) during spring 2010. Sampling time was 4 to 10 days for particles 50, 40, or 30 nm in diameter. Sample air flow was 4 L/min. The sampling setup was arranged so that two samples were obtained for each sampling period almost simultaneously: one containing particles and adsorbed gas- phase compounds and one containing adsorbed gas-phase compounds only. Filters were extracted and analyzed for the presence of selected carboxylic acids, polyols, nitrogen- containing compounds, and aldehydes. The results showed that, in quartz filter samples, gas-phase adsorption may be responsible for as much as 100% of some compound masses. Whether quartz or Teflon, simultaneous collection of gas-phase zero samples is essential during the whole sampling period. The dependence of the adsorption of gas- phase compounds on vapor pressure and the effect of adsorption on the deposited aerosol layer are discussed. Keywords Atmospheric aerosols . Differential mobility analyzer . Filter . Teflon . Quartz Introduction Extensive studies have been made of the chemical composition of atmospheric aerosols and reviews have appeared in the literature [1, 2]. Numerous papers have been published on the analysis of all-sized and PMx aerosol particles. However, except for direct mass spectrometric analyses, little effort has gone into determining the chemical composition of nanometer-sized particles because of the challenging sample collection and low mass of organic carbon [3–5]. We recently introduced a differential mobility analyzer (DMA) for the size separation of ambient atmospheric aerosols before filter sampling [6, 7]. With the use of DMA, particles under 100 nm can be reliably collected on the filter. Information about the chemical composition of these small particles, especially organic compounds, is critical if we are to understand the nucleation and growth of aerosols in the atmosphere [8]. It is well known that quartz, which is the preferred filter medium, adsorbs gas-phase compounds during sampling and thus produces positive artifacts. This result may be a significant overestimation of the organic carbon mass in atmospheric aerosols [9]. Two suggested solutions to the problem are to use two quartz filters, one for the aerosols and one as a back-up filter [10], or to use Teflon as the aerosol filter and quartz as the back-up [11]. The drawback of both approaches is the high adsorption of some gas- phase compounds on the first filter, especially on quartz. The back-up filter cannot then provide reliable information about the gas-phase contribution. Clearly, a new approach J. Parshintsev : J. Ruiz-Jimenez : K. Hartonen : M.-L. Riekkola (*) Laboratory of Analytical Chemistry, Department of Chemistry, University of Helsinki, PO Box 55, 00014 Helsinki, Finland e-mail: marja-liisa.riekkola@helsinki.fi T. Petäjä : M. Kulmala Division of Atmospheric Sciences, Department of Physics, University of Helsinki, P O Box 64, 00014 Helsinki, Finland Anal Bioanal Chem (2011) 400:3527–3535 DOI 10.1007/s00216-011-5041-0