Pergamon .L Aerosol Sci, Vol. 28, Suppl. I, pp. $445-$446, 1997 ©1997 Elsevier Science Ltd. All rights reserved Printed in Great Britain pII:S0021-8502(97)00269-3 0021-8502/97 $1%00+0.00 A SYSTEM FOR ON-LINE CHEMICAL ANALYSIS OF AEROSOL SPECIES P. Mikuska ~, A. Khlystov 2, H.M. ten Brink 2, G.P. Wyers 2, J. Slanina 2 1Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, Veveoi 97, CZ- 61142 Brno, Czech Republic e Netherlands Energy Research Foundation (ECN), P.O. Box 1, 1755 ZG Petten, The Netherlands KEYWORDS aerosol collector, on-line chemical analysis One of the fundamental aerosol properties most relevant to environmental issues is its chemical composition. For many areas of investigations e.g. the radiative forcing of aerosols, studies of industrial process emission as well as health related studies, it is necessary to measure aerosol composition with a reasonable time resolution. Furthermore, measurements of temporal and spatial changes in the relative concentrations of different species in aerosols can give considerable insight into the origin of particles. At the moment aerosols are mostly sampled by filter (packs), which are very labor intensive and suffer from sampling artifacts [ 1]. Especially at low ambient concentrations errors by contamination during the handling of the filters is problematic. In order to avoid these problems there is a need for automated systems that can measure aerosol composition on-line with a time resolution of an hour and which are free of sampling artifacts. Recently a new type of aerosol collector, the so-called Steam-Jet Aerosol Collector (SJAC) has been developed [2], which opens the way for on-line analysis of aerosol. A SJAC operates in the following way. First, a denuder [3] removes interfering gases from the sample air stream. Then the air is mixed with steam. Cooling results in a high supersaturation and causes aerosol particles to grow into large droplets. These droplets containing dissolved aerosol species are easily collected in a cyclone. The collected solution is (constantly) pumped out and is online analyzed by means of ion chromatography (IC) and flow-injection analysis (FIA). A combination of a SJAC sampler and an automated IC and FIA-unit have been built and tested in this study. The automated IC and FIA unit have been especially developed to be coupled to samplers of the SJAC type with the aim to be operated in the field for long periods without much maintenance and are described elsewhere [4,5]. The sample stream (e.g. produced by the SJAC at a rate of 1 to 2 ml per minute) is split into two lines. One is pumped to the IC and the other - to the FIA ammonium detector. The characteristics of this instrument are the following: • Time resolution is in the order of 15 minutes. • Accuracy depends on the measured concentrations and is between 1 and 5 % relative. • An internal standard is used for calibration of the IC and FIA and provides quality assurance and quality control. • Detection limits are in the order of a few ppb in the sample. • The blanks of the system are at the level of a few ppb or less. $445