Study of Analysis Condition for Restoring Wide Boiling Range Compounds in Environmental Samples with TD-GC/MS Restore Function

Poster Presentation

Prepared by , N. Lock, W. Lipps

Contact Information: [email protected]; 410-910-0821


Toxic organic compounds (TOCs) are monitored in various places (i.e. workspace air, Ambient air). The most representative analysis method of TOCs is U.S. EPA Compendium Method TO-17. In this method, collecting volatile organic compounds (VOCs) in sorbent tubes using active sampling pump and analyze them with Thermal Desorption-Gas Chromatograph/Mass Spectrometer (TD-GC/MS), however, which takes time to collect sample. So it is common to collect samples in multiple tubes or use TD restore function.

With the restore function, VOCs in sorbent tube are desorbed and trapped on 2nd trap, then 2nd trap is heated and VOCs are introduced into column with split injection mode. While injecting, split flow are once again trapped into the sorbent tube. Even if a problem occurs, the sample can be measured again, so that even precious trace samples can be analyzed without difficulty. The problem of restore function is difficulty of trapping wide range compounds from low-boiling compounds to high-boiling compounds at the same time. When restoring the sample, it is difficult to trap low-boiling compounds because the sorbent tube remains high temperature just after the desorption. It is common to replace the sorbent tube before injection, however the risk is of replacing sorbent tube is leakage. If leakage occurs, both analysis and restore are failed. To avoid failure, restoring original sorbent tube is effective. It is necessary to cool the sorbent tube quickly, and set the temperature of sample line as low as possible. Besides, if the temperature of sample line is too low, high-boiling compounds likely to carry over.

In this study, we consider the analysis condition of TD-GC/MS restore function to collect wide boiling range compounds with an excellent recovery factor. In poster presentation, we will report the analysis result of STD and real samples following U.S. EPA Compendium Method TO-17 to evaluate the sensitivity and quantitativity using restore function.