Sample size and retention values in gradient liquid chromatography of synthetic polymers

Retention times in gradient liquid chromatography of synthetic polymers are often dependent on sample size. They increase with column load if the separation mechanism is governed by a solution process but decrease with increasing load if the mechanism is governed by adsorption. Since retention times independent of sample size are a prerequisite for peak identification as well as for the correct measurement of elution bands of samples with a broad distribution, measures to counteract sample-size effects deserve attention. Usually both solubility and adsorption are effective in gradient liquid chromatography of synthetic polymers. An appropriate balance of both effects is suitable for diminishing the influence of sample size on retention time of synthetic polymers. Ternary gradients allowing independent control of solubility and adsorption are promising.