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2007 vol. 4
Chemical/Petrochemical
Complete Resolution of Benzene from
Ethanol in Spark Ignition Fuels
Using a Modified ASTM D3606-06e1 Method and the New D3606 Column Set
By Barry L. Burger, Petroleum Innovations Chemist
• Easy, accurate quantification of aromatics.
• Fully conditioned column set—ready to use out of the box.
• Each column set is tested for method applicability and includes chromatogram.
Laboratories analyzing reformulated spark igni-
tion fuels that contain ethanol for the determina-
tion of benzene and toluene must use a modified
ASTM D3606-06e1 method to prevent the coelu-
tion of ethanol and benzene. This method modifi-
cation is also a requirement of the US EPA. The
benzene range of determination is 0.1 to 5% by
volume, and the toluene range is 2 to 20% by vol-
ume. The primary challenge in this analysis is
twofold: the tailing of the ethanol peak, and the
retention time shift of the aromatics towards
ethanol, specifically benzene merging quickly into
the ethanol peak and preventing accurate quantifi-
cation.
Restek has resolved these issues by developing a
new D3606 column set for this modified ASTM
D3606-06e1 application. Column 1 is a 6' x
1
/
8
" OD
(1.8m x 2mm ID) nonpolar Rtx®-1 phase which
separates components by boiling point. After the
elution of
n
-octane (C8), Column 1 is backflushed
to prevent heavier compounds from entering
Column 2, the main analytical column. The light
compounds pass into Column 2, a 16' x
1
/
8
" OD
(4.9m x 2mm ID) column packed with a new pro-
prietary polymer that fully resolves the aromatic
compounds.
To demonstrate the performance of this new col-
umn set, we installed it in an Agilent 6890 GC
equipped with a flame ionization detector (FID).
Helium was used as the carrier gas at 20mL/min.
in the constant flow mode. The data in Figure 1
show that the aromatic compounds are fully
resolved, and can easily be quantified using the
internal standard, sec-butanol.
This column set is fully conditioned and ready to
use right out of the box. Only a brief (10 min.) car-
rier gas purge at ambient temperature, followed by
a 30 min. hold at 165°C, is required. If your labo-
ratory has been struggling with ASTM method
D3606-06e1 for reformulated fuels containing
ethanol, Restek’s new column set is the solution.
Figure 1
Complete resolution of benzene from ethanol using a
D3606 column set and modified ASTM D3606-06e1 method.
Column:
D3606 Column Set
column 1: 6' x
1
/
8
" OD (1.8m x 2mm ID), nonpolar Rtx
®
-1 polymer
column 2: 16' x
1
/
8
" OD (4.9m x 2mm ID), proprietary packing
Sample:
0.05µg/µL; C7 (26%), ethanol (10%) benzene(10%),
sec
-butanol (26%),
toluene (26%)
Inj.:
0.05µL, direct injection
Inj. temp.:
200°C
Carrier gas:
helium, constant flow
Flow rate:
20mL/min.
Oven temp.:
135°C, isothermal
Det.:
FID @ 250°C
1. C7
2. ethanol
3. benzene
4.
sec
-butanol (IS)
5. toluene
GC_PC00961
D3606 Application Column (2 column set)
*Please add column instrument configuration suffix number to cat.# when ordering.
**This column set is for a valving system; therefore, packing material is filled to ends of columns.
Description
cat.#*
price
D3606 Application Column (2 column set)**
Column 1: 6' (1.8m),
1
/
8
" OD, 2.0mm ID, nonpolar Rtx
®
-1
Column 2: 16' (4.9m),
1
/
8
" OD, 2.0mm ID, proprietary packing material
83606-
$525
Excellent
resolution
of benzene
and ethanol!
new
!
Column Instrument Configurations
General
Configuration
Suffix -800
Agilent
5880, 5890,
5987, 6890:
Suffix -810
Varian 3700,
Vista Series,
FID:
Suffix -820
PE 900-3920
Sigma 1,2,3:
Suffix -830
8
3
/
4
"
PE Auto System
8300, 8400, 8700
(Not On-Column):
Suffix -840
6
1
/
2
"
Note: Initial 2" of column will be
empty, to accommodate a needle.
For a completely filled column (not
on-column), add suffix -901.