Waters 1525EF, Installation And Maintenance Manual

Page: 105 / 111

Solvent Considerations 105
C
Conclusions
With any of the above techniques, the eluent reequilibrates to air saturation in 12 to 24
hours, depending on the eluent.
Degassing by vacuum or sonication or both is often performed for improved pump
performance in multipump gradient applications.
C.8 Wavelength Selection
The tables in this section provide UV cutoff values for:
• Common solvents
• Common mixed mobile phases
• Chromophores
UV Cutoffs for Common Solvents
Table C-6 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 due to the absorbance of the solvent.
Table C-6 UV Cutoff Wavelengths for Common Chromatographic Solvents
Solvent UV Cutoff (nm) Solvent UV Cutoff (nm)
1-Nitropropane 380 Ethylene glycol 210
2-Butoxyethanol 220 Isooctane 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