Oral: Surface Deactivation for the Analysis of Low Level Acidic, Basic, and Neutral Compounds for EPA 8270E

Environmental laboratories are working towards implementing low-level detection methods using highly sensitive gas chromatography instrumentation such as gas chromatography tandem triple quadropole mass spectrometry (GC-MS/MS). Reactive surfaces in the flow-path of the GC-MS/MS contribute to problems in analyte peak shapes, complicating instrument calibration and consistency. Reagents used in GC column production vary between manufacturers, imparting different types of activity from that surface that becomes more apparent at low levels. Residual silanols at the fused silica surface impart acidity to the column, affecting the performance of acids, bases, and neutrals in different ways, depending on the chemistry used for deactivation. More information is needed to understand the impact of surface deactivation on low level analyses where residual activity is exacerbated and more likely to affect productivity. In this study, we evaluated activity of acidic, basic, and neutral compounds associated with the Environmental Protection Agency’s method 8270E, comparing performance at low-levels (0.1-10 pg on column). The columns evaluated were all 5% phenyl, 95% dimethyl polysiloxane columns sourced from multiple manufacturers. Results show how column selection affects analytical performance of acidic, basic, and neutral analytes at low-levels.