The Performance of Thermal Desorption for the Analysis of High-Boiling SVOCs Compared to Standard Methods

Air Methods & Monitoring
Oral Presentation

Presented by N. Watson
Prepared by

Contact Information: nwatson@markes.com; 866-483-5684


ABSTRACT

Anthropogenic semi-volatile organic compounds (SVOCs) are widely found in numerous matrices, including air, water, soil, indoor construction materials, certain consumer goods and foods. They include pollutants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), phthalates and flame retardants, many of which are subject to regulation due to their known or suspected health effects. Reliable analysis of these compounds is therefore vital for many environmental monitoring campaigns, and increasingly for product quality control.
Monitoring SVOCs in ambient air has traditionally involved pumped sampling of large volumes of air through a quartz or glass fibre filter to collect the particulate fraction, backed-up with a polyurethane foam cartridge or other sorbent to trap the vapour-phase fraction. Analytes are then solvent extracted from the two phases and concentrated using rotary evaporation or other traditional techniques, with analysis of
the concentrated extracts by GC or GC–MS.
However, these approaches suffer from several disadvantages, including:
• The need for labour-intensive solvent-based sample preparation steps.
• Incomplete and/or variable extraction efficiency, which compromises repeatability.
• Susceptibility to errors such as artefact introduction and losses of the more volatile target compounds during concentration steps.
• The need for cumbersome, mains-powered high-flow sampling pumps.
The technique of thermal desorption (TD), in conjunction with GC or GC–MS, has been used for several decades to overcome these issues for the monitoring of lower-boiling airborne volatile organic compounds (VOCs), and is now increasingly being applied to SVOC measurement. As well as completely avoiding the need for manual solvent extraction/ dilution and its associated disadvantages, TD offers a huge improvement in sensitivity because of the use of two-stage sample focusing, which allows
smaller air volumes to be collected using portable batteryoperated low-flow pumps. TD also interfaces with the same type of GC–MS analytical equipment widely used for monitoring VOCs such as benzene in ambient air. Data will be shown comparing TO-17 style sample collection and TO-13 style sample collection showing improvements to this set up.