Fast GC for real time detection accepted at #AIHCE


Title: Fast GC-PID/FID Analyses Using Resistively Heated Columns for Rapid Analyses in the Field

Topic 1: Real-Time Detection Systems
Presentation Start: 6/19/2012 10:50:00 AM
Presentation End: 6/19/2012 11:10:00 AM
Author Block: J. Driscoll, PID Analyzers, LLC, Sandwich, MA; P. Smith, US DOL, Salt Lake City, UT; S. Stearns, VICI Valco Instruments, Houston, TX.
Presentation Number: SR-111-2
Abstract: Objective:
Gas chromatographic analysis times for ketone and aromatics methods (NIOSH 1301, 1501 & 2005) are between 25-35 minutes due to long temperature ramping and cooling times. Also, if peaks are not resolved chromatographically, non-target components may interfere with the analysis. We employed resistively heated columns to reduce the total analysis times by 50-60%, and used the PID/FID response ratios to enhance identification of components of interest.
A field-portable GC with an external laptop was used for the analysis. The column used incorporates new technology based on fused silica tubing (FST). The typical polyimide layer is removed and nickel is electroplated on the outside of the FST column. Superior heat transfer characteristics of the nickel coating allows rapid and efficient heating, and excellent resolution using a 30 m capillary column. A mini-FID was designed that will easy attach to the outlet of the PID in a single detector port to provide improved analyte identification.
Initial runs with a series of 12 ketones showed complete separation for 10 of the components by increasing the ramp rate from 10 to 20 degrees C/min, also reducing analysis time to 11 minutes. Separately, we separated 15 of the 17 aromatic target compounds in 14 minutes instead of 35 minutes. Nitrobenzene and naphthalene were not resolved, but the large difference in the PID/FID response ratios for these analytes allows easy identification.
We have shown that the resistively heated columns can be used to improve both separations and time of analysis in a field-portable instrument. The use of a second detector (FID) for confirmation of peak identity is more helpful for faster separations where complete resolution is not attained.


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