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Figure 2
Analyte levels in samples are unknown; only inert columns, which prevent
concentration from affecting retention time, can assure accurate results.
Figure 3
An Rxi column gives
the best overall performance
for both basic and acidic
compounds.
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
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 column contains active sites. The
remarkable neutrality of Rxi® columns solves this problem and allows a wide range of compounds to be ana-
lyzed with high sensitivity, often on a single column. All Rxi® columns are exceptionally inert as demon-
strated in Figure 3 by high response factors for both pyridine (basic) and 2,4-dinitrophenol (acidic). Rxi®
columns reliably produce highly symmetric peaks and improved responses for difficult compounds, indi-
cating greater inertness than columns produced by other manufacturers (Figure 4).
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
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
2ng pyridine
2ng 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?
Contact support@restek.com or
your local Restek representative
for helpful, knowledgeable
technical support.
Website : www.chromtech.net.au E-mail : info@chromtech.net.au TelNo : 03 9762 2034 . . . in AUSTRALIA