Atmospheric Environment Vol.27A,No. 15, pp. 2435-2439,1993. 001)4-6981/93 $6.00+0.00 Printed in Caeat Britain. PergamonPressLtd TECHNICAL NOTE BLANK VALUES OF TRACE ELEMENTS IN AEROSOL FILTERS DETERMINED BY ICP-MS TORUNN BERG and ODDVAR ROYSET Norwegian Institute for Air Research, P.O. Box 64, N-2001 Lillestrom, Norway and EILIV STEINNES Department of Chemistry, University of Trondheim, AVH, N-7055 Dragvoll, Norway (First received 5 April 1993 and in final form 20 June 1993) Abstract--Blank values of 30 elements in 19 different filter types from Gelman, Millipore, Nuclepore and Whatman have been compared. The filter media were extracted with dilute nitric acid and the element contents determined by ICP-MS. Large differences in blank values were observed between different filter materials. Glass fiber filters showed high blank values for a number of elements, whereas PTFE filters were generally the cleanest. However, most filter types showed high blank values of one or more elements of environmental interest. Key word index: Blank values, trace elements, aerosol filters, air, ICP-MS. INTRODUCTION Field blanks are usually the limiting factor in determining low amounts of an element in air particles. Such a field blank depends on: • possible contamination during the field and sample prep- aration procedures; • purity of the reagents used; • presence of the element in sampling equipment such as air filters. The two first criteria can usually be kept low by using high purity reagents and careful preparation procedures. The background value coming from the filter material may con- tribute more to the total blank value, and is often the dominant source of the field blank. The blank values from the filter materials are therefore important to consider in Table 1. Filter materials investigated Manufacturer Type Filter material Remarks Pore size Diameter (#m) (mm) No. Geiman Sciences Zefluor (P5PJ047) Membrane PTFE Gelman Sciences TF-1000 (66155) Membrane PTFE/polypropylene Gelman Sciences GN-4 Metric, el (64679) Membrane cellulose esters Gelman Sciences DM Metricel (64502) Membrane vinyl/acryl copolymer Gelman Sciences Versapor 1200 (4600000) Membrane acryl/nylon copolymer Gelman Sciences Supor-800 (60110) Membrane polysulfone Gelman Sciences GLA-5000 (66468) Membrane PVC Gelman Sciences A/E (61631) Glass fiber Millipore fluoropore (FALP 04700) Membrane PTFE/polyethylene Millipore MF (AAWP 04700) Membrane cellulose esters Nuclepore fn memb (131110) Membrane PTFE/polypropylene Nuelepore mf memb (141109) Membrane cellulose esters Nuclepore pc memb (111109) Membrane polycarbonate Nuclepore pc memb (111132) Membrane polycarbonate (apiezon coated) Nuclepore PVC memb (361550) Membrane PVC Whatman WCN (7190004) Membrane cellulose nitrate Whatman W 40 (1440047) Cellulose Whatman GF/A (1820037) Glass fiber Whatman QM-A (1851047) Quartz fiber 2 47 2 1 47 1 0.8 47 5 0.8 47 9 1.2 50 12 0.8 47 11 5 47 10 47 16 1 47 3 0.8 47 6 1.0 47 4 0.8 47 7 0.8 47 13 8 47 14 0.8 37 15 1.0 47 8 47 19 37 17 47 18 * The values for all filter types have been adjusted to 47 mm. 2435