ADV01-05_1-298

• 5 •

www.restekcorp.com

800-356-1688

Restek has developed a fast GC/MS method for ana-

lyzing semivolatile compounds [e.g., US

Environmental Protection Agency (EPA) Method

8270] that will help increase productivity in the

lab. The changes include modification of the final

extract volume, use of the DI Uniliner with a hole,

shorter GC analysis time, and a modification of the

calibration curve to offset the increased extract vol-

ume. Following is an explanation of each modifica-

tion. For more detailed information, please request

application note #59125.

1) Increase the extract volume

Increase the final extract volume from 1mL to 5mL.

This will reduce preparation time and the amount

of low-boiling compounds lost from evaporation.

Also, one-fifth the amount of matrix imterferences

will be injected into the GC. The reduction of matrix

interferences will allow the instrument to stay cali-

brated for more sample windows.

2) Use a Uniliner

DI injection port liner

with a hole

This unique inlet liner can be used for direct and

splitless injection. The column is fixed via a press-

tight connection at the bottom of the liner, eliminat-

ing any sample contact with metal parts below the

liner. In order for the carrier gas to be routed

through the split vent line, a hole has been drilled

into the side of the liner. This hole allows the carri-

er gas to be vented through the split vent line dur-

ing the split operation of the injection port. The

Uniliner

liner with a hole provides a more inert

sample pathway that minimizes injection port dis-

crimination and active compound loss.

3) Use a thin-film Rtx

-5Sil MS column

Lower concentration standards allow the use of a

Fast Semivolatile Analysis by

GC/MS Using Performance-

Based Measurement Systems

Rtx

-5Sil MS Columns and

Uniliner

Liners

✔

Decrease analysis time to 22 minutes for increased lab throughput.

✔

Resolve key analytes.

✔

Analytical conditions can be used for all MS detectors.

thinner-film column, which can reduce analysis

time. A thin-film Rtx

-5Sil MS column can achieve

improved resolution of difficult-to-analyze com-

pounds in less than 22 minutes. This column fea-

tures a silarylene stationary phase and optimized

dimensions that are ideal for the analysis of semi-

volatile compounds (Figure 1).

4) Oven temperature programming

Adjusting the oven temperature program of the GC

will help optimize the separation of critical pairs.

Use of an initial hold time resolves early-eluting

compounds; then a fast ramp rate can be used

through non-critical areas, and a lower ramp rate

used to elute later compounds.

5) Calibration curve

We used

the recommended concentration level

of Method 8270—1µL injection of 4, 10, 16, 24,

and 32ppm standard. Notice how the 4ppm (4ng

on-column) injection shows excellent signal-to-

noise ratio, and low column bleed and injection

port discrimination (Figure 1).

Conclusion

A number of techniques can be used to increase

sample throughput for the analysis of semivolatile

compounds according to US EPA Method 8270.

Increasing extract volume will reduce preparation

time and injection port contamination. Using a

Uniliner

injection port liner with a hole results in

a more inert sample pathway and eliminates injec-

tion port discrimination. In addition, the use of a

thin-film column reduces analysis time.

Figure 1

Fast analysis of Method 8270 semivolatile compounds with a Uniliner

liner achieves excellent

signal-to-noise ratio, and low bleed and injection port discrimination.

30m, 0.25mm ID, 0.25µm Rtx

-5Sil MS (cat.# 12723)

Inj.:

1µL splitless injection of 8270 Calibration Mix #1 (cat.# 31618), 8270 Calibration Mix #2

(cat.# 31619), 8270 Calibration Mix #3 (cat.# 31620), 8270 Calibration Mix #4 (cat.# 31621), 8270

Calibration Mix #5 (cat.# 31622), BN Surrogate (cat.# 31024), Acid Surrogate (cat.# 31025), SU Internal

Standard (cat.# 31006);

Flow rate:

helium, constant flow @ 1mL/min.;

Oven temp.:

35°C (hold 2 min.)

to 260°C @ 20°C/min. to 330°C @ 6°C/min. (hold 1 min.);

Inj. temp.:

300°C;

Detector:

Agilent 6890 w/

5973 MS;

MS transfer temp.:

280°C;

Inlet liner:

4.0mm ID Uniliner

w/hole (cat.# 21054)

Rtx

-5Sil MS

(fused silica)

Length (m)

ID (mm)

df(µm)

Temp. Limits

cat.#

0.25

-60 to 330/350°C

0.25

0.50

-60 to 330/350°C

Uniliner

Liner with Hole

4.0mm ID, 6.3mm OD, 78.5mm length

each

5-pk.

21054, $60

for

more

info

on the analysis of semivolatile compounds,

request lit. cat.# #59411,

A Guide to

Preparing and Analyzing Semivolatile

Organic Compounds.

pyridine

benzo(g,h,i)perylene

4ng on

column

by Gary Stidsen, Innovations Team Manager

GC_EV00539

21055

12723

0.25

12738