Optimizing the Analysis of Volatile Organic Compounds
Optimizing the Analysis of Volatile Organic Compounds
Optimizing the Analysis of Volatile Organic Compounds
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Gasoline <strong>Analysis</strong> with Oxygenates and Alcohols<br />
Success <strong>of</strong> gasoline range organics (GRO) analyses are based on <strong>the</strong> ability <strong>of</strong> <strong>the</strong> analytical<br />
column to resolve oxygenates from <strong>the</strong> alkanes, alkenes, and, to a lesser extent, alkynes. To<br />
minimize false positive results for methyl-tert-butyl e<strong>the</strong>r (MTBE) it is important to separate<br />
this analyte from 2-methylpentane and 3-methylpentane. Ano<strong>the</strong>r potential interference is<br />
tert-butyl alcohol (TBA). Both MTBE and TBA elicit response on a PID, and <strong>the</strong>y share<br />
ions used in MS detection, so <strong>the</strong>y must be resolved regardless <strong>of</strong> which detector is used.<br />
Figure 46 is an example <strong>of</strong> GRO target compounds analyzed using PID detection, with <strong>the</strong><br />
oxygen-containing gasoline additives resolved from <strong>the</strong> o<strong>the</strong>r analytes.<br />
Figure 46.<br />
An Rtx ® -VGC column resolves oxygen-containing gasoline derivatives from o<strong>the</strong>r GRO.<br />
1. 2-methylpentane<br />
2. 3-methylpentane<br />
3. methyl-tert-buyl e<strong>the</strong>r<br />
4. tert-butyl alcohol<br />
5. diisopropyl e<strong>the</strong>r<br />
6. ethyl-tert-butyl e<strong>the</strong>r<br />
7. isooctane<br />
8. n-heptane<br />
9. benzene<br />
10. tert-amyl-methyl e<strong>the</strong>r<br />
11. α,α,α-trifluorotoluene<br />
12. toluene<br />
13. 1-chloro-3-fluorobenzene<br />
1 2<br />
4<br />
5<br />
6<br />
3<br />
8<br />
7<br />
9<br />
10<br />
11<br />
14. ethylbenzene<br />
15. m-xylene<br />
16. p-xylene<br />
17. o-xylene<br />
18. isopropylbenzene<br />
19. ethylmethylbenzene<br />
20. 1,3,5-trimethylbenzene<br />
21. 1,2,4-trimethylbenzene<br />
22. 4-bromochlorobenzene<br />
23. naphthalene<br />
24. 2-methylnaphthalene<br />
25. 1-methylnaphthalene<br />
12<br />
13 14<br />
15, 16<br />
30m, 0.45mm, 2.55 m Rtxfi min. 5 10 15 20<br />
GC_EV00465<br />
-VGC (cat.# 19408)<br />
each component 100ppb in 5mL <strong>of</strong> RO water, except tert-butyl alcohol 5000ppb; 2/1-methynapthalene 150ppb;<br />
ethylmethylbenzene 50ppb.<br />
Concentrator: Tekmar LSC-3100 Purge and Trap<br />
Trap: Vocarb 3000<br />
Purge: 11 min. @ 40mL/min. @ 35 C<br />
Dry purge: 1 min. (MCS bypassed)<br />
GC: Finnigan 9001<br />
Oven temp.: 40 C (hold 2 min.) to 130 C @ 6 C/min. (hold 0 min.) to 230 C @ 30 C/min. (hold 2 min.).<br />
Carrier gas: helium @ ~8mL/min.<br />
Detector: Thermo Finnigan PID, make-up 7mL min., purge 7mL/min., set @ 0.35mV, base temperature 200 C.<br />
17<br />
18<br />
19<br />
20<br />
21<br />
22<br />
23<br />
24<br />
25<br />
49<br />
www.restekcorp.com
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