Figure 3
An Rxi®-5ms column gives
the highest response for both basic
and acidic compounds.
38
GC COLUMNS |
HIGH-PERFORMANCE RXI COLUMNS
Rxi® Columns Over view
Improved Response for Difficult Compounds
Another reason column inertness is important for trace-level analysis is that many acidic,
basic, and polar compounds will tail significantly and become difficult to analyze if the col-
umn contains active sites. The remarkable neutrality of Rxi® columns solves this problem
and allows a wide range of compounds to be analyzed with high sensitivity, often on a sin-
gle column. All Rxi® columns are exceptionally inert as demonstrated in Figure 3 by high
response factors for both pyridine (basic) and 2,4-dinitrophenol (acidic). Rxi® columns reli-
ably produce highly symmetric peaks and improved responses for difficult compounds,
indicating greater inertness than columns produced by other manufacturers (Figure 4).
2.10 2.20 2.30 2.40 2.50 2.60 2.70 2.80 Time.
GC_EX01118
extracted ion chromatogram, m/z 79
GC_EX01119
2.25 2.30 2.35 2.40 2.45 2.50 2.55 2.60
Time.
A: Pyridine on non-Rxi® column
Predictable retention
times, regardless of
concentration; easy,
accurate integration.
B: Pyridine on-Rxi® column
Retention times vary with
concentration; poor peak
shape requires manual
integration and additional
review.
10 ng, 2.26 min.
2.5 ng, 2.28 min.
1.0 ng, 2.32 min.
10 ng, 2.39 min.
1 ng, 2.40 min.
0.5 ng, 2.41 min.
0.000
0.200
0.400
0.600
0.800
1.000
Rxi-5ms
ZB-5
ZB-5 MS
VF-5ms
HP-5ms
DB-5ms
DB-5
0.000
0.050
0.100
0.150
0.200
0.250
0.300
Rxi-5ms
ZB-5
ZB-5 MS
VF-5ms
HP-5ms
DB-5ms
DB-5
2 ng of pyridine
2 ng of 2,4-dinitrophenol
Column
Column
Response Factor (RF)
Response Factor (RF)
Comparison of 30m x 0.25mm ID, 0.25μm
columns.
Innovation & Service
“When my research group needed a
GC column for a chiral separation,
Restek was the only company that
offered to provide us with test
columns to evaluate. The willingness
of Restek to work with us to find a
solution to our separation problem is
exceptional.”
Joe Dinnocenzo,
Professor of Chemistry
Director, Center for
Photoinduced Charge Transfer
University of Rochester
How can we help you today?
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Figure 2
Analyte levels in samples are unknown; only inert columns, which pre-
vent concentration from affecting retention time, can assure accurate results.
Figure 4
Rxi® columns are the most inert columns on the market providing
the most symmetric peak shape for basic compounds, such as pyridine.
DB-5
ZB-5
ZB-5ms
Rxi
®
-5ms
DB-5ms
VF-5ms
Symmetric peaks give high response
and predictable retention times.
HP-5ms
Comparison of 30m x 0.25mm ID, 0.25µm 5% diphenyl columns, 2ng pyridine on-column, helium carrier gas,
Oven temp.: 50°C (3 min.) to 180°C @ 35°C/min. (5 min.), Det.: FID @ 250°C
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Mar 2011
