Post on 05-Apr-2018
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Rapid Separations on a Portable GC
with Resistively Heated Columns
J. N. Driscoll
PID Analyzers, LLC
&Stanley Stearns
Valco Instruments, Inc.
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Introduction
Much of the previous work on fast GC utilized short (5M) thin film capillary
columns to elute solutes quickly and the result is rapid but inferior
separations because of the short column. New technology developed at
Valcos capillary column development center where VICI takes polyimide-
coated fused silica (FST) and removes the polyimide layer. Then the (FST) is
electroplated with nickel. As a result of the superior heat transfer of theelectroplated nickel, we are able to rapidly and efficiently heat and achieve
excellent resolution for a 30M capillary column.
These columns can be programmed faster (hundreds of degrees/min)- save
50-90%
The columns can be reliable started a few degrees above ambient These columns cool down faster because of their low mass so savings> 50%
Stearns et al (J. Chromat.) have looked at high MW HC but we are looking at
applications for low MW HC with thick films (5-10m)
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Photo of Resistively Heated GC Gas
Analysis System
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Photo GC 312
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Fast GC Electronic Schematic
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PW Software for GC Cont. &
Integration
VICI Column SW w PW Display PeakWorks Chromatography SW
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Fast GC for High MW HC
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Comparison of Applications
The previous slide from Stearns shows thedramatic effect of TP for high MW organics up toC30 where analysis times can be reduced by 50-90% and cool down times by >50%.
Our applications at PID are in lower MW HC up toC6 but also C1. Here we have to start just aboveto ambient, a difficult task for most GCs, w/osubamb. We were able to start @ 23oC
(reproducibly), hold 1 min, then prog. to 200oC(
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Isothermal Chromatogram C1 to C6 on GC312
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C1 to C6 HC by cap GC
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Fast GC Chromatogram for C1 to C6 alkanes
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Temp. Programming Comparison
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Chromatogram of Gasoline Vapor
0
2000
4000
6000
8000
10000
12000
0 50 100 150 200 250 300 350 400
FIDR
esponse
Time -sec
FID- Gasoline Vapor from Tank HS
Series1
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Solvents (BTX + MeOH)
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Conclusions
We have shown similar results with low MW HC-namely 50% reduction in analysis times
There are eight different ramps that can beprogrammed so that separations can be improved in
different sections Although we have worked with thick films, these
columns are available with thin films for high MWcompounds and with PLOT columns for separation oflow MW gases
Very fast < 10 second chromatograms can also beproduced easily for studying reaction kinetics inchemical analyses.