8
7a -flow rate: 2.1cc/min. (µ: 40cm/sec.)
7b -flow rate: 5.1cc/min. (µ: 80cm/sec.)
7c -flow rate: 9.0cc/min. (µ: 120cm/sec.)
1. phenol
2. 2-chlorophenol
3. 2-nitrophenol
4. 2,4-dimethylphenol
5. 2,4-dichlorophenol
6. 4-chloro-3-methylphenol
7. 2,4,6-trichlorophenol
2 4 6 8 10 12 14 16 18 20 22 24 26 min.
Figure 7.
When usedwith direct injections, 0.32mm or 0.53mm ID columns perform better at elevated flow rates.
Use only high-quality septawhenmaking direct injections
Because all of the carrier gas flow is directed into the inlet of the column, high-quality, low-
bleed septamust be usedwith direct injection systems that are not equippedwith a septum
purge.Volatile compounds that are released from septamaterial after heating in an injection
port canmake their way onto the column if not vented off using a septum purge. These com-
poundswill focus at the head of the columnwhen using low flow and low temperature con-
ditions andwill be displayed as ghost peaks in the chromatogram, or as increased back-
ground or column bleed.
8. 2,4-dinitrophenol
9. 4-nitrophenol
10. 2-methyl-4,6-dinitrophenol
11. pentachlorophenol
1µL direct injection ofMethod 604 - Phenols CalibrationMix (cat.# 31029),
using an open-topUniliner
®
injector liner
Oven temp:
50°C (hold 4min.) to 250°C@ 8°C/min. (hold 5min.)
Inj./Det. temp.:
250°C/300°C
Carrier gas:
hydrogen
Direct injections canbeperformedwithorwithout using the solvent focus-
ingmechanisms normally required for splitless injections. If solvent focus-
ing is used, the 0.32mm or 0.53mm ID column can be operated at flow
rates closer to the predicted optimum, because early-eluting compounds
will be recondensed at the head of the column. If solvent focusing is not
used, employ a faster carrier gas rate to narrow the sample band at the
head of the column.
12
3,4 5
6 7
8
9
10
11
12
3 5
6 7
8
9 10
11
4
12
3 5 6
7
8
9 10
11
4
2 4 6 8 10 12 14 16 18 20 22 24 min.
2 4 6 8 10 12 14 16 18 20 22 24 min.
