Feasibility study of preparation and certification of reference materials for nitrogen dioxide and sulfur dioxide in diffusive samplers

Abstract

This paper presents the results of a feasability study for the preparation and certification of reference materials (RMs) for nitrogen dioxide (NO(2)) and sulfur dioxide (SO(2)) in diffusive samplers. RMs for NO(2) were prepared by exposure to gas mixtures in a chamber while the RMs for SO(2) were prepared by liquid spiking. Certification of RMs for NO(2) was found feasible with a certified uncertainty of 5.8% and a proposed shelf life of 5 years. The uncertainty was calculated with contribution from the homogeneity of preparation, stability and transport of the CRMs and from an external verification of the certified value. To reach 5.8% of uncertainty, the contribution of the differences between the results of analysis by ion chromatography and colorimetry must be eliminated. It is proposed to solve this by pre-extracting the samplers with water before analysis. The results of this study indicate that the samplers are stable for at least two years before and after exposure when stored in a refrigerator. By contrast, the certification of RMs for SO(2) was found to not be feasible due to instability problems. This instability was attributed to reaction of sulfate on the walls of the samplers. Alternatively, the preparation of RMs by simultaneous exposure to SO(2) and NO(2) has been tested. Satisfying homogeneities has been reached both for NO(2) and SO(2).

Laboratory and field comparison of measurements obtained using the available diffusive samplers for ozone and nitrogen dioxide in ambient air

“…The laboratory experiments were performed in an exposure chamber 25 that allowed controlling of concentration level, temperature, relative humidity and wind velocity (Fig. 2).…”

Indoor air quality of newly built low-energy preschools – Are chemical emissions reduced in houses with eco-labelled building materials?

“…The expanded uncertainty of the method was estimated to be AE22%. Moreover, sample blanks and procedural blanks were simultaneously analysed, using the method described by Yanagisawa and Nishimura, 21 Gerboles et al 22 and method 6014 outlined in the National Institute for Occupational Safety and Health (NIOSH) manual. 23 The laboratory participates in the LGC (Laboratory of the Government Chemist) Standard interlaboratory study Proficiency Testing (Air-PT) four times per year with satisfactory results.…”

The use of hierarchical clustering for the design of optimized monitoring networks

“…Passive sampling techniques have several advantages such as ease of deployment, no power requirements, and low maintenance, and they have been used as an alternative to continuous monitors for monitoring temporal trends of air pollutants in remote areas (Krupa and Legge, 2000;Cox, 2003;Seethapathy et al, 2008;Bytnerowicz et al, 2010) and evaluation of air quality of large areas (Gerboles et al, 2006). Their disadvantages are low sensitivity, inability to resolve short-duration concentration peaks, and adverse effects of meteorological conditions on reported observations (Tang et al 1997(Tang et al , 1999Krupa and Legge, 2000;Tang, 2001;Kirby et al, 2001;Partyka et al, 2007;Fraczek et al, 2009;Salem et al, 2009;Zabiegala et al, 2010;Vardoulakis et al, 2011).…”