3
visit
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
or
your local Restek representative
for helpful, knowledgeable
technical support.
Website :
E-mail :
TelNo : 03 9762 2034 . . . in AUSTRALIA
