High-resolution liquid chromatography on the basis of a sawtooth gradient

A method for analyzing a polymer sample, the method consisting of performing a liquid chromatography analysis on a chromatography column with a mobile phase comprising a mixture of at least one nonsolvent (S1) and at least one solvent (S2) for the polymer sample, wherein the proportion by volume of S2 in the mobile phase is varied in a stepwise manner during the elution process and that the steps are alternately ascending and descending, wherein either

• a) the mobile phase consists of a nonsolvent S1 and a solvent S2 and the composition of the mobile phase is varied over time as follows, with regard to step, time, proportion of S1 and proportion of S2, respectively:
• Step x:
• t
• 100 − S2
• SP + (x − 1)*B
• C · t
• 100 − S2
• SP + (x − 1)*B − A
• D · t
• 100 − S2
• SP + (x − 1)*B − A
• E · t
• 100 − S2
• SP + x*B
• where the parameters A, B, C, D, and E are selected from the following ranges A:
• 0.01-100% vol % of S2 and B:
• 0.01-100% vol % of S2 and C:
• 0-100 and D:
• 0-100 and E:
• 0-100;
• or
• b) the mobile phase consists of two nonsolvents S1 and S1′ and a solvent S2 and the composition of the mobile phase is varied over time as follows, with regard to step, time, proportion of S1, proportion of S2, and proportion of S1, respectively:
• Step x:
• t
• 0
• SP + (x − 1)*B
• 100 − S2
• C · t
• 100 − S2
• SP + (x − 1)*B − A
• 0
• D · t
• 100 − S2
• SP + (x − 1)*B − A
• 0
• 0.01
• 0
• SP + (x − 1)*B − A
• 100 − S2
• t
• 0
• SP + (x − 1)*B − A
• 100 − S2
• E · t
• 0
• SP + x*B
• 100 − S2
• where the parameters A, B, C, D, and E are selected from the following ranges A:
• 0.01-100% vol % of S2 and B:
• 0.01-100% vol % of S2 and C:
• 0-100 and D:
• 0-100 and E:
• 0-100.