This application note describes how to use the Saturn GC/MS system to measure ozone precursors in ambient air, including volatile organic compounds (VOCs), hydrocarbons, and nitrogen oxides.
This document details a method for measuring ozone precursor volatile organic compounds (VOCs) in ambient air using the Varian (now Agilent) Saturn Air System. The technique utilizes a built-in automated concentrator to trap samples on glass beads at -180°C, allowing for the analysis of small sample volumes (60-100 mL) instead of the larger volumes typically required.
The note outlines specific instrumentation conditions, including column temperatures and flow rates, and lists 24 ozone precursors specified by EPA method TO-14. It demonstrates the system's sensitivity with chromatograms showing detection limits as low as 0.1 ppb for compounds like hexane.
| Sample Flow Rate | 20 mL/min |
|---|---|
| Column Flow Rate | 1 mL/min |
| Auxiliary Flow Rate | 20 mL/min |
| VTAT Temperature (Trapping) | -180°C for 4 min |
| Column Temperature Program | -60°C for 6 min, 8°C/min to 160°C |
| Scan Range | 35-260u |
| Emission Current | 20 pA |
The analysis time is reduced because concentration takes place in 3-5 minutes instead of the commonly used 20-30 minutes.
Ethylene, Acetylene, and Isoprene are marked as being detected by FID.