Inlet Systems

Split/splitless capillary inlet

Table 6-2. Some Common Solvents: Suggested Initial Oven

Temperatures to Use the Solvent Effect

Solvent

Boiling Point

Suggested Initial Oven

 

(^C)

Temperature Range (^C)

 

 

 

 

Diethyl Ether

36

10 to

25

n-Pentane

36

10 to

25

Methylene Chloride

40

10 to

30

Carbon Disulfide

46

10 to

35

Chloroform*

61

25 to

50

Methanol*

65

35 to

55

n-Hexane

69

40 to 60

Ethyl Acetate*

77

45 to

65

Acetonitrile

82

50 to

70

n-Heptane

98

70 to 90

i-Octane

99

70 to

90

Toluene

111

80 to 100

* Should be used only with cross-linked stationary phases.

The best solvent for a given application is found by trial and error, depending upon sample solubility and volatility, column polarity and type of stationary phase, and detector selectivity/sensitivity.

Note that, because of the solvent effect, retention times for the same components, but dissolved in different solvents, may be different: the solvent, once chosen for a particular application, should be used throughout.

Cold trapping

Cold trapping is a second mode of reconcentration: where column temperature is low enough, vaporized components may condense into the liquid phase.

116