The use of multi-channel silicone rubber traps as denuders for polycyclic aromatic hydrocarbons

Abstract

HIGHLIGHTS:o Two multi-channel silicone rubber traps separated by a quartz fibre filter are characterized as a miniature portable denuder o Gas and particle phase polycyclic aromatic hydrocarbons can be separately sampled and analysed o Calculated particle transmission efficiencies were 100 % for particles > 50 nm diameter o Experimental particle transmission efficiencies were 100 % for particles > 200 nm and decreased to < 60 % for particles < 20 nm diameter o Short sampling intervals are possible which provides high temporal resolution for air pollution studies Analytica Chimica Acta Novelty StatementTwo multi-channel silicone rubber traps separated by a quartz fibre filter are characterized as a miniature portable denuder, which allows for the separate sampling and analysis of gas and particle phase polycyclic aromatic hydrocarbons. Calculated particle transmission efficiencies were 100 % for particles > 50 nm diameter, whilst experimental particle transmission efficiencies were 100 % for particles > 200 nm and decreased to < 60 % for particles < 20 nm diameter. Short sampling intervals are possible which provides high temporal resolution for air pollution studies. , separated by a quartz fibre filter for particle phase collection. The denuder only requires a small portable personal sampling pump to provide sampling flow rates of ~0.5 L min -1 . Theoretical considerations indicated that the air flow through the denuder was expected to be laminar, and the linear velocity arising from longitudinal diffusion was found to be negligible. The calculated particle transmission efficiency through the denuder was found to be essentially 100 % for particles > 50 nm, whilst the experimental overall efficiency, as determined by CPC and SMPS measurements, was 92 ± 4 %. The size resolved transmission efficiency was < 60 % for particles below 20 nm and 100 % for particles larger than 200 nm. Losses could have been due to diffusion and electrostatic effects. Semi-volatile gaseous analytes are pre-concentrated in the silicone of the trap and may be thermally desorbed using a commercially available desorber, allowing for total transfer and detection of the collected analytes by GC-MS. This enhances detection limits and allows for lower sampling flow rates and shorter sampling times, which are advantageous for studies requiring high temporal resolution.

Two multidimensional chromatographic methods for enantiomeric analysis of o,p′-DDT and o,p′-DDD in contaminated soil and air in a malaria area of South Africa

“…Briefly, four litre of indoor air was sampled with a denuder device consisting of a multichannel PDMS trap + micro quartz fibre filter + multichannel PDMS trap combination to sample air borne vapour phase DDT (first PDMS trap) and air borne particulate phase DDT (filter and back-up PDMS trap) in a single step. A denuder allows simultaneous collection of molecules and transmission of aerosol particles through the silicone rubber tubes based on the large difference in radial diffusion speeds in the axial laminar flow environment [29].…”

Monitoring of atmospheric gaseous and particulate polycyclic aromatic hydrocarbons in South African platinum mines utilising portable denuder sampling with analysis by thermal desorption–comprehensive gas chromatography–mass spectrometry

“…Further detail on this denuder setup is provided in [20]. The PDMS in the multi-channel traps acts as an absorbent for semi-volatile organic compounds (including PAHs) therefore sample recovery is expected to be higher due to absorption taking place rather than adsorption.…”

“…The efficiency of these novel denuder devices has been investigated from both theoretical and experimental perspectives and they have been utilised in a number of applications including household fire emissions, sugar cane burning emissions and in tunnel air pollution studies [20], [21].…”

Particle emissions from household fires in South Africa

“…After ignition of the fire, 1 kg of charcoal was added. Gas and particle phase emissions were collected by a miniature denuder, consisting of two silicone rubber traps in series with a quartz fibre filter between them [7,8], at 1 L.min -1 for 10 min (Fig. 6).…”