what's quasi-binary mixture

[Austin]

Hi, everyone!

I read a literature and some words puzzled me:

Straight line approximations can only be used for quasi-binary mixtures, i.e. ternary mixtures in which the ratio of the volume fractions of the two organic modifiers is constant.

Woops, I'm confused, what the relationship between the quasi-binary and ternary mixture on earth? Can anyone give me some information, thanks in advance!

[tom jupille]

Imagine a binary system where the A reservoir contains water and the B reservoir contains a 1:1 mix of ACN and MeOH. If you set the system to blend 50%B (i.e., a binary mixture of A+B), you are actually using a ternary blend of 50% water, 25% ACN, and 25% MeOH.

The terminology ("quasi binary") is awkward, but the practice is fairly common.

[Austin]

Tom, thanks for your goodwill!

Your information gave me some inspiration and I studied the Drylab software(evaluation), and I found that the ternary isocratic separation model uses this terminology-quasi-binary mixture, but it is not a linear relationship between logarithm of retention(k') and organic concentration, but a quadratic equation. Maybe it really is the amazing point of chemistry!

Best regards

Austin