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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.