Solvent Miscibility; Viscosity - Waters Prep Series Installation And Maintenance Manual

Solvent miscibility

Before changing from one solvent to another, see the table below to determine
the miscibility of the solvents being used. The following considerations apply
when changing solvents:
• Changes involving two miscible solvents are made directly. Changes
involving two solvents which are not totally miscible (for example, from
hexane to water) require an intermediate solvent (such as methanol or
THF).
• Solvent miscibility is affected by temperature. If operating at an
elevated temperature, consider the effect of the higher temperature on
solvent solubility.
• Buffers dissolved in water can precipitate salts when mixed with organic
solvents. When switching from a strong buffer to an organic solvent,
flush the buffer out of the system with distilled water before adding the
organic solvent. Also, when using a strong buffer, flush all pathways
with distilled water before shutting the system down and leave distilled
water in the system (flush with 10% methanol in water for shutdowns
scheduled to be more than one day).
Physical properties of solvents
Polarity
Solvent
index
0.3 N-decane
0.4 Isooctane
0.0 N-hexane
0.0 Cyclohexane
C.7 Butyl ether
C.8 Triethylamine
2.2 Isopropyl ether
2.3 Toluene
2.4 P-xylene
3.0 Benzene
3.3 Benzyl ether
a
Boiling

Viscosity

Point °C
CP, 20 °C
(1 atm)
0.92 174.1
0.50 99.2
0.313 68.7
0.98 80.7
0.70 142.2
0.38 89.5
0.33 68.3
0.59 10C.6
0.70 138.0
0.65 80.1
5.33 288.3
Miscibility
Wavelength
Number
Cutoffs (nm)
(M)
29 —
29 210
29 —
28 210
26 —
26 —
— 220
23 285
24 290
21 280
— —
Solvent miscibility D-3