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Universal Angled Press-Tight® Connectors
Siltek ®-treated Universal Angled Press-Tight® Connectors
• 9 • 800-356-1688 • 2005 vol. 3
Method D-6730-01 suggests using helium as the carrier gas, at a linear veloc-
ity of 24cm/sec. (approximately 2.3mL/min.). The tridecane (C13) retention
time this combination yields, approximately 146 minutes, greatly limits sam-
ple throughput per day. Our enhanced Rtx®-1PONA column meets or exceeds
all criteria in the method, but does so in 30% less time: retention time for C13
is 97 minutes, using helium as the carrier gas.¹ In most applications hydrogen
is a better alternative to helium as the carrier gas, because it can be used at
much higher linear velocities without compromising critical resolutions.
A revision to ASTM D 6730-01 proposed by Neil Johansen Inc. (Aztec, New
Mexico), in association with Envantage Analytical Software Inc. (Cleveland,
Ohio), has established optimal DHAX (detailed hydrocarbon analysis—extend-
ed) parameters, including specifying hydrogen as the carrier gas. Using these
conditions, analysis time is reduced to within 71 minutes (C13)—a 53% reduc-
tion versus using helium as the carrier gas. The method also is extended to
include middle distillates having final boiling points up to 509°C/948°F ( n-C38).
Restek provided Neil Johansen Inc. with an enhanced Rtx®-1PONA column
(100m x 0.25mm ID x 0.5µm df) and an Rtx® 5PONA tuning column for
DHAX method development. The Rtx®-1PONA column was connected to 3
meters of the tuning column through a Universal Angled Press-Tight®
Connector (cat.# 20446) and was installed in a PerkinElmer AutoSystem XL
GC equipped with a flame ionization detector and programmable pneumatic
control. The data system used was ChromPerfect Spirit (Justice Laboratory
Software, Denville, NJ). Individual compounds were identified by using
Dragon- DHA software, developed by Envantage Analytical Software Inc. in
association with Neil Johansen Inc., which uses algorithms to process high-
resolution chromatographic data. Processed data for the PONA VI reference
standard, containing more than 400 individual components of finished gaso-
line, can be reviewed on the Restek website:
The proposed DHAX method was optimized with hydrogen carrier gas at a
rate of 3.62mL/min, constant flow, producing a linear velocity of 55cm/sec.
The new Rtx®-1PONA column was conditioned in less than two hours, as fol-
lows: 35°C for 15 min., to 300°C at 10°C/min., hold 30 min., cool to 35°C.
Dead time was adjusted to elute methane at 3.50 ±0.05 min., then a DHA/oxy-
genates setup blend was introduced into the column to determine the col-
umn’s suitability for the method.
Figure 1A lists the measured critical criteria. Once established that the column
met the method criteria, GC oven program parameters were entered and trial
injections of the DHA/oxygenates setup blend were begun. The analysis was
permitted to run until n-C13 was eluted. Based on the resolutions achieved,
the length of the tuning column was reduced incrementally until all critical
pairs met D-6730-01 specifications. In this example application, the appropri-
ate tuning column length was 2.36 meters. Figure 1B indicates the critical
pairs. The full analysis of the 400-plus component PONA VI reference stan-
dard, listing retention indices (RIs) calculated using Dragon-DHA software, is
posted on the Restek website.
The benefits of using hydrogen carrier gas for the PONA analysis are obvious:
all critical components are resolved, per method D-6703-01, in the greatly
reduced time of 70.5 minutes (C13), versus 146 minutes or 97 minutes using
helium. Relative to the results anticipated in the method, we virtually doubled
sample throughput.
We evaluate each column for film thickness, column efficiency, peak skewness,
selectivity, resolution, and bleed to guarantee performance and reproducibili-
ty from column to column. The redesigned Rtx®-1PONA column earned
Restek chemists the Concluded Research Award at the 2004 Gulf Coast
Conference. When you use an Rtx®-1PONA column, we think you’ll agree the
award was well justified.
Rtx®-1PONA Column (fused silica)
(Crossbond ® 100% dimethyl polysiloxane)*
*Optimized phase for hydrocarbon analysis
ID df (µm) temp. limits length cat. #
0.25mm 0.50 -60 to 300/340°C 100-Meter 10195
Rtx®-5PONA Tuning Column (fused silica)
(Crossbond ® 5% diphenyl/95% dimethyl polysiloxane)
ID df (µm) temp. limits length cat. #
0.25mm 1.0 -60 to 325°C 5-Meter 10196
Universal Angled Press-Tight® Connectors
• Ideal for connecting a tuning column to an
analytical column.
• Inert fused silica.
• Angle reduces strain on the connection.
• Fit all column ODs from 0.33–0.74mm
(Restek 0.1mm–0.53mm ID).
5-pk./price 25-pk./price 100-pk./price
20446 20447 20448
20482 20483 20484
Reference
1. Stidsen, G. and B. Burger, Enhanced Rtx®-1PONA Column Improves
Detailed Hydrocarbon Analysis, Restek Advantage 2005v1: 12 (2005).
please note
To achieve critical resolutions in detailed hydrocarbon analysis, a
5-meter 5% diphenyl/ 95% dimethyl polysiloxane tuning column
(Rtx®-5PONA) is connected to the analytical column and adjusted
to the needed length through a series of trial analyses.
for more info !
Processed data for the PONA VI reference standard, containing
more than 400 individual components of finished gasoline, can be
reviewed on the Restek website: