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2005 vol. 3

American Society for Testing and Materials test

method D-3606-99 is focused on measuring ben-

zene and toluene in finished motor and aviation

gasolines: benzene can be determined from 0.1%

to 5% by volume and toluene from 2.0% to 20%

by volume. The method requires two columns

connected in series. Typically, column A is a 0.8

meter x 1/8 inch stainless steel packed column

containing a 10% loading of a nonpolar stationary

phase, such as Rtx

-1 or OV®-101. This column

separates sample components by boiling point.

After n-octane (C8) elutes, the column is back-

flushed to prevent heavier compounds from enter-

ing column B, the main analytical column. The

light compounds, C8 and below, pass into column

B, a 4.0 meter x 1/8 inch stainless steel packed col-

umn containing highly polar 1,2,3 tris(2-cya-

noethoxy) propane (TCEP). Here, the aromatic

compounds are separated from the non-aromat-

ics, and quantitative information is obtained.

For method D-3606-99, micropacked column

technology is an efficient, practical, time-saving

alternative to 1/8 inch packed columns.

Micropacked column A is a 0.8 meter x 1/16 inch

x 1mm ID Silcosteel

column packed with 10%

Rtx®-1 crosslinked on 60/80 Chromosorb

WAW.

Micropacked column B is a 4.0 meter x 1/16 inch x

1mm ID Silcosteel

column packed with 20%

TCEP on 80/100 Chromosorb

PAW. We installed

the columns in an Agilent 6890 GC capillary inlet,

configured in the on-column injection mode using

our Micropacked Column Adaptor Kit for On-

Column Injection (cat.# 22425). We used hydro-

gen as the carrier gas and, to attain the 9mL/min.

flow rate, we adjusted the column head pressure to

44psig at 145°C.

Figure 1 illustrates the analysis of a sample con-

taining 1% benzene, 2% toluene, and internal

standard methyl ethyl ketone (MEK), in

-pentane

(C5). The cycle time, just under 3 minutes, is

greatly reduced, relative to the 8 minute cycle

imposed by 1/8 inch packed columns and helium

carrier gas. The micropacked column / hydrogen

carrier gas combination reduces analysis time by

63%, nearly tripling sample throughput. If you are

performing method D-3606-99 analyses, and time

is important to you, we highly recommend this

micropacked column approach.

Rapidly Determine Benzene and Toluene in Gasolines

Micropacked GC Columns Reduce Analysis Time by 63%

By Barry Burger, Petroleum Applications Chemist

• 3-Minute Cycles for ASTM Method D-3606-99.

• Nearly triple sample throughput.

• Easy set-up, using Restek adaptor kit.

Figure 1

Benzene, toluene, and internal standard resolved in 3

minutes, using a micropacked column.

Micropacked Columns

1/16 inch micropacked columns containing 10% Rtx

-1 on 60/80

Chromosorb

W or 20% TCEP on 80/100 Chromosorb

PAW are prepared on

request. For details, please contact your Restek representative.

Micropacked Inlet Conversion Kits

Convert a capillary GC split/splitless inlet for use with

" OD micropacked

columns.

• For use with Agilent 5890 and 6890 GCs.

• Sample pathways deactivated for ultimate inertness.

*For use with packed column FIDs only.

Description

qty.

cat.#

Micropacked Column Adaptor Kit for On-Column Injection*

Complete kit with FID and injection port adaptors

Kit includes: Dual Vespel

Ring Inlet Seal, large bore; reducing nut, large

bore; FID adaptor, large bore;

" ferrule, Vespel

/graphite;

" nut,

stainless steel;

" ferrules, Vespel

/graphite (2); Siltek

-treated metal

liner installation guide;

" nuts, stainless steel (2)

kit

22425

1. non-aromatics

2. benzene

3. methyl ethyl ketone (int. std.)

4. toluene

GC_PC00775

Column:

A: 10% Rtx

1 on 60/80 Chromosorb

WAW, 0.8m x

inch x 1mm ID Silcosteel

tubing

B: 20% TCEP on 80/100 Chromosorb

PAW, 4.0m x

inch x 1mm ID Silcosteel

tubing

connected in series and using Micropacked Column On-Column Injection Kit (cat.# 22425)

Sample:

benzene, toluene, methyl ethyl ketone in pentane

Inj.:

1.0µL, on-column, 4mm ID splitless inlet liner (cat.# 20772)

Carrier gas:

hydrogen, constant flow

Flow rate:

9.0mL/min.

Inj. temp.:

200°C

Oven temp.:

145°C

Det.:

FID @ 200°C