ADV01-05_1-298

• 6 •

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Figure 1

The Rtx

-5MS column and a combined system can separate dioxin-like PCBs

and dioxins/furans.

Inj. temp.:

280°C;

Carrier gas:

helium;

Det.:

Agilent 6890 GC coupled to a Micromass Ultima HRMS @10,000RP.

20m, 0.1mm ID, 0.1µm Rtx

-5MS (custom cat.# 58136)

Column head pressure:

100psi;

Oven program:

100°C (hold 1 min.) to 200°C @ 100°C/min, to 235°C @ 13°C/min.,

to 300°C @ 27°C/min. (hold 4 min.);

Inj. volume:

0.2mL

40m, 0.18mm ID, 0.18µm Rtx

-5MS (custom cat.# 550590)

Column head pressure:

61psi;

Oven program:

100°C (hold 0.62 min.) to 200°C @ 64.5°C/min, to 235°C @ 4.8°C/min.

(hold 6.2 min.), to 300°C @ 9.7°C/min.( hold 5.6 min.);

Inj. volume

1.0mL

Fast Analysis of Dioxin

& Related Compounds

Using an Rtx

-5MS Column

Historically, chlorinated dioxins and furans have

been analyzed by gas chromatography (GC) sepa-

rately from polychlorinated biphenyls (PCBs). In

1998, the World Health Organization (WHO)

reported toxic equivalent factors (TEFs) for the 12

dioxin-like PCB congeners.

This enabled concen-

trations of PCBs to be expressed in terms of

2,3,7,8-TCDD, the most toxic form of dioxin. Using

similar methods to analyze dioxins and PCBs allows

detection limits up to three orders of magnitude

lower than that of conventional of PCB congener

methods. The toxicity of a single sample now can

be reported in toxic equivalents of 2,3,7,8,-TCDD

(i.e., toxic equivalent quantities [TEQ]) by sum-

ming the toxic equivalents of each of the 17 toxic

dioxin congeners and 12 dioxin-like PCB con-

geners.

Extracts were prepared according to Canada's

Ministry of the Environment (MOE) Method 3418,

which is similar to the combination of US

Environmental Protection Agency (EPA) Methods

1613 and 1668. The extracts are further cleaned

using activated carbon.

This allows for the collec-

tion of two sample extract fractions: one containing

the dioxins, furans, and coplanar PCBs; and the

other containing the remaining PCBs, chlorinated

and brominated diphenyl ethers, and other non-pla-

nar organic compounds. The chlorinated diphenyl

ethers interfere with the furans and, therefore, they

need to be analyzed separately. Normally, dioxins

and furans, and PCBs (congeners) are analyzed sep-

arately on a 60m analytical column using GC/high

resolution mass spectrometry (GC/HRMS) with

analysis times of 50 to 90 minutes each.

Because an MS is used for detection, many analysts

want a column with the lowest bleed possible. Some

laboratories may use silarylene columns (e.g., Rtx

5Sil MS or DB-5MS

columns) due to their low

bleed feature. However, these columns yield a coelu-

tion between 2,3,7,8-TCDD and 1,2,3,9-TCDD; and

their elution orders and retention times will differ

from the phase for which the window performance

mixtures were designed. The Rtx

-5MS (5%

diphenyl/95% dimethyl polysiloxane) column is bet-

ter suited to meet the performance standards for this

analysis. It separates all of the important com-

pounds, and each one is individually tested to pro-

vide low bleed levels for MS detection.

Chromatographic resolution and analysis time also are

dependent on column dimensions (i.e., length, ID,

phase thickness). Experimentally, we have found

175,000 plates are required to obtain separation of

2,3,7,8-TCDD from its nearest neighbors (1,2,3,7- and

1,2,3,8-TCDD—the unresolved pair eluting before;

and 1,2,3,9-TCDD—the compound eluting after).

40m Rtx

-5MS column meets this criterion, and can

complete the analysis in approximately half as much

time as a 60m column. A 20m column is capable of

meeting these requirements in about one-quarter the

time of a 60m column; however, there is little tubing

length available for trimming to maintain column per-

formance. Therefore, we suggest using a 40m column.

To minimize the number of ions that must be moni-

tored simultaneously, elute the bulk of PCB com-

pounds prior to eluting dioxin and furan com-

pounds. Accomplish this by injecting the non-copla-

nar PCB fraction into a 20m Rtx

-5MS column that is

set up parallel (i.e., two separate injectors) to a 40m

Rtx

-5MS column, which is used for the separation

of the dioxin/furan/coplanar PCB fraction. Both frac-

tions are injected simultaneously. The columns are

installed into the MS ion source in parallel.** The

resulting analysis time is less than that for a single

fraction on a conventional 60m column (Figure 1).

For the analysis of dioxin-like PCBs and

dioxins/furans, method consolidation and through-

put increase is possible when using a parallel, dual-

column system with GC/HRMS. This method allows

the combination of several different analytical meth-

ods to a single system, and results in a total analysis

time of less than 30 minutes for elution of

octachlorodibenzodioxin. If your laboratory is

involved in the analysis of dioxin and related com-

pounds, and you would like more detailed informa-

tion on this method, please contact Restek Technical

Service at 800-356-1688 or 814-353-1300, ext. 4.

References

1.Berg, M. V., L. Birnbaum, A.T.C. Bosveld, B. Brunstrom, P. Cook,

M. Feeley, J.P. Giesy, A. Hanberg, R. Hasegawa, S.W. Kennedy, T.

Kubiak, J.C. Larsen, F.X.R. Leeuwen, A.K.D. Liem, C. Nolt, R.E.

Peterson, L. Poellinger, S. Safe, D. Schrenk, D. Tillitt, M.

Tysklind, M. Younes, F. Waern, and T. Zacharewski,

Environmental Health Perspectives, 106 (1998), p. 775.

2.Kolic T.M., K. A. MacPherson, E.J. Reiner, T. Gobran, and A.

Hayton, Organohalogen Compounds, 46 (2000), p. 562.

3.Reiner E.J., K.A. MacPherson, R. Brunato, T. Chen, M.A. Bogard,

A.R. Boden, and G. Ladwig, Organohalogen Compounds, 45

(2000), p. 17.

by Karen MacPherson, Eric Reiner, Ph.D.,* & Frank Dorman, Ph.D.

✔

Rtx

-5MS Columns

(Crossbond

5% diphenyl - 95% dimethyl polysiloxane) Stable to 360°C

For the complete Rtx

-5MS column offering, refer to Restek’s

Annual Chromatography Products Guide

(lit. cat.# 59960).

Length

df (µm)

temp. limits

cat.#

20-Meter

0.10mm

0.10

-60 to 330/350°C

58136

40-Meter

0.18mm

0.18

-60 to 330/350°C

550590

*Karen MacPherson and Dr. Eric Reiner, Ontario Ministry of the Environment.

**For more information on the system set-up, request Applications Note #59343.

GC_EV00392