Using Miscibility Numbers (M-Numbers) - Waters ACQUITY UPLC I-Class IVD System Manual

• Temperature affects solvent miscibility. If you are running a
high-temperature application, consider the effect of the higher
temperature on solvent solubility.
• Buffers dissolved in water can precipitate when mixed with organic
solvents.
Solvent miscibility:
Polarity
Solvent
index
0.0 N-hexane
1.8 Triethylamine
4.3 1-propanol
4.3 2-propanol
5.2 Ethanol
5.5 Benzyl alcohol
5.7 Methoxyethanol
6.2 Acetonitrile
6.2 Acetic acid
6.4 Dimethylformamide
6.5 Dimethylsulfoxide
6.6 Methanol
9.0 Water

Using miscibility numbers (M-numbers)

Use miscibility numbers (M-numbers) to predict the miscibility of a liquid
with a standard solvent.
To predict the miscibility of two liquids, subtract the smaller M-number value
from the larger M-number value.
• When the difference between the two M-numbers is 15 or less, the two
liquids are miscible, in all proportions, at 15°C.
• A difference of 16 indicates a critical solution temperature from 25 to
75 °C, with 50 °C as the optimal temperature.
Viscosity Boiling
cP, 20 °C point °C
(@1 atm) (@1 atm)
0.313 68.7
0.38 89.5
2.30 97.2
2.35 117.7
1.20 78.3
5.80 205.5
1.72 124.6
0.37 81.6
1.26 117.9
0.90 153.0
2.24 189.0
0.60 64.7
1.00 100.0
July 7, 2014, 715003736IVD Rev. C
Solvent miscibility
Miscibility
λ Cutoff
number
(nm)
(M)
29 ––
26 ––
15 210
15 ––
14 210
13 ––
13 ––
11, 17 190
14 ––
12 ––
9 ––
12 210
–– ––
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