Factors governing the retention of solutes on chromatographic immobilized artificial membranes : Application to anti-inflammatory and analgesic drugs

The performance of two different types of immobilized artificial membrane (IAM) stationary phases, IAM PC DD 1 and IAM PC DD 2 was studied with a series of model compounds as well as anti-inflammatory and analgesic drugs. The influence of the composition of the mobile phase and sample preparation on the chromatographic retention of selected compounds was investigated. Premature column failure was evidenced for both types of columns by a continuous decrease of k'IAM values over time. pH of the mobile phase strongly influenced k'IAM value of ionizable compounds. The k'IAM value of the neutral form was always 2 to 7 fold higher than the value of the corresponding ionized form, depending on the compound and the type of IAM. A linear relationship was found between log k'IAM and the percentage of acetonitrile in the mobile phase. However, extrapolation of the log k'IAM value at 0% acetonitrile was improved when the pH and the ionic strength of acetonitrile-containing mobile phases were adjusted to the values of...