
Solvent considerations
75
Solvent miscibility
Liquid carbon dioxide functions as a nonpolar organic solvent much like
iso-octane or n-hexane. At conditions slightly above the critical point, liquid
carbon dioxide would possess a miscibility number of 28 or 29. As temperature
and pressure are increased on liquid carbon dioxide, its solvating power and
miscibility increase. This allows it to dissolve or mix with increasingly polar
compounds and solvents. Well into the supercritical region, supercritical
liquid carbon dioxide would exhibit miscibility properties similar to p-xylene,
toluene and benzene.
UV cutoffs for common solvents
The table below shows the UV cutoff (the wavelength at which the absorbance
of the solvent is equal to 1 AU) for some common chromatographic solvents.
Operating at a wavelength near or below the cutoff increases baseline noise
because of the absorbance of the solvent.
UV cutoff wavelengths for common chromatographic solvents:
Solvent
UV cutoff
(nm)
Solvent
UV cutoff
(nm)
1-Nitropropane
380
Ethylene glycol
210
2-Butoxyethanol
220
Iso-octane
215
Acetone
330
Isopropanol
205
Acetonitrile
190
Isopropyl chloride
225
Amyl alcohol
210
Isopropyl ether
220
Amyl chloride
225
Methanol
205
Benzene
280
Methyl acetate
260
Carbon disulfide
380
Methyl ethyl ketone
330
Carbon tetrachloride 265
Methyl isobutyl
ketone
334
Chloroform
245
Methylene chloride
233
Cyclohexane
200
n
-Pentane
190
Cyclopentane
200
n
-Propanol
210
Diethyl amine
275
n
-Propyl chloride
225
Dioxane
215
Nitromethane
380
Содержание ACQUITY UPC2
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