CLINICAL/FORENSICS
6
Barbiturates
GC
Barbiturates
These acidic andneutral drugs normally are analyzed in their underivatized forms. Symmetricpeaks andbaseline resolution for
many compounds canbe achievedbyusing intermediatepolarityRestek columns,Rtx®-35 andRtx®-1701. Indrugoverdose or
drug abuse testing, these two columns can be used in combination, in dual column analysis for screening and tentatively con-
firming thepresenceor absenceof specific compounds.Differences inpolarity for each stationaryphaseproduce shifts in reten-
tion time and elutionorder.High thermal stability and low columnbleed allow these drugs tobe detectedby FIDwithon-col-
umn concentrations in the lownanogram range.When analyzingunderivatizedbarbiturates, a deactivated inlet liner shouldbe
used in the injectionport toprevent adsorptiononto the surfaceof the liner.Liners shouldbe changed frequently toprevent the
accumulationof non-volatile contamination.
Toavert injectionport adsorptionproblems,barbiturates alsocanbeanalyzedbygas chromatography in theirderivatized forms.
They canbe derivitizedon-column, usingmethylating reagents likeTMAHorTMPAH.
6 7 5
30m, 0.53mm ID, 1.0µmRtx
®
-35 (cat.# 10455)
1.0µL splitless injection
Conc.:
50µg/mL
Oven temp.:
100°C to 280°C@
10°C/min. (hold 5min.)
Inj. & det. temp.:
250°C/ 275°C
Carrier gas:
helium
Linear velocity:
40cm/sec. set@ 100°C
FID sensitivity:
5.12 x 10
-10
AFS
Splitless hold time: 0.5min.
Barbiturates (Underivitized)
Rtx®-35
1
2
3
4
8
9
11
10
12
13
16
15
14
min. 0
5
10
15
20
GC_PH00262
1. ethosuximide
2. barbital
3. methyprylon
4. aprobarbital
5. butalbital
6. amobarbital
7. pentobarbital
8. secobarbital
9. meprobamate
10. carisoprodal
11. glutethimide
12. phenobarbital
13. methaqualone
14. primidone
15. carbamazepine
16. diphenylhydantoin
15m, 0.53mm ID, 0.50µmRtx
®
-1701
(cat.# 12037)
1.0µL splitless injection
Conc.:
50µg/mL
Oven temp.:
100°C to 280°C@ 7°C/min.
Inj. / det. temp.:
250°C / 275°C
Carrier gas:
helium
Linear velocity:
40cm/sec. set@ 100°C
FID sensitivity:
5.12 x 10
-10
AFS
Splitless hold time: 0.5min.
6 7
Barbiturates (Underivatized)
Rtx®-1701
1
2
3
4
5
8
9
10
14
11
12
13
15
16
min. 0
5
10
15
20
GC_PH00263
1. ethosuximide
2. methyprylon
3. barbital
4. aprobarbital
5. butalbital
6. amobarbital
7. pentobarbital
8. secobarbital
9. glutethimide
10. meprobamate
11. carisoprodal
12. phenobarbital
13. methaqualone
14. carbamazepine
15. primidone
16. diphenylhydantoin
