The Mechanism of Chromatographic Retention - The Association of Methanol with Water > Page 35

Taking the molar fractions of water, methanol and water/methanol associate as (XM),(XW) and (XMW), respectively,

(20)

(21)

(22)

Considering a mixture of methanol and water

(23)

where (Ri) is the molar refractivity of the solvent mixture,
(RM) is the molar refractivity of methanol,
(RW) is the molar refractivity of water,
and (RMW) is the molar refractivity of the methanol/water associate.