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Extending the Power of Stabilized PLOT Column
Technology to Process GC Analyzers
By Jaap de Zeeuw, Rick Morehead, and Tom Vezza
• New technology ensures consistent
flows and predictable retention times.
• Rugged metal MXT® tubing stands up
to process GC analyzer conditions.
• Available with all major adsorbents in
3.5” coils or on 7” 11-pin cages.
Porous layer open tubular (PLOT) columns
are useful for analyzing volatiles in petro-
chemical product streams, as the specialized
adsorbents provide good resolution and fast
analysis times. However, conventional PLOT
columns suffer from poor mechanical stabil-
ity, limiting their use in process analyzers,
which require robust columns for continual
operation. Recently Restek developed new
PLOT column bonding techniques that result
in improved layer stability, consistent flow
behavior, and more reproducible retention
times. This technology, which was first devel-
oped for fused silica columns, has now been
transferred to metal MXT® tubing, resulting
in rugged columns that outperform typical
metal PLOT columns and are ideal for pro-
cess GC analyzers.
New Technology Improves
Column Stability
Restek’s PLOT columns are stabilized through
a proprietary process that is based on con-
centric adsorption layers and improved
particle bonding. New MXT® PLOT columns
show greater thermal stability and much less
phase bleed than the comparable competi-
tor product (Figure 1). Lower bleed improves
sensitivity and ensures faster stabilization
times.
Bleed comparison: Q type porous polymer columns were conditioned at 250 °C for equivalent periods and then tested to evaluate tempera-
ture stability. Split vent flow rate: 150 mL/min.; Oven: 250 °C (hold 10 min.) to 40 °C at 50 °C/min.; Carrier gas: hydrogen, constant pressure
(4 psi, 27.6 kPa); Detector: FID@ 250 °C.
Figure 2: Conventional PLOT
columns show continuous
spiking resulting from particle
generation. In contrast, the
Restek column showed spikes
during only the 2 initial analyses
out of 240.
New low bleed MXT®-Q-BOND PLOT columns
• Faster stabilization
• Better sensitivity
GC_PC1187
Varian, Q type PLOT MXT®-Q-BOND PLOT
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NumberofAnalyses with>2Spikes
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Restek MXT®-Q-BOND PLOT
Figure 1: The bonding technology used in new MXT® PLOT columns increases thermal
tolerance, resulting in lower bleed, faster stabilization times, and higher sensitivity.
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NumberofAnalyses with>2Spikes
PressureCycles (Analytical RunNumber)
Varian,“Q”Type PLOT
Website : E-Mail : TelNo : 03 9762 2034 . . . in AUSTRALIA