Performance of four mixed-mode solid-phase extraction columns applied to basic drugs in urine

Four different mixed-mode cation exchange solid-phase extraction columns were compared for extraction of basic drugs from urine using HPLC-DAD analysis: Isolute HCX-3, ABN, Bond Elut Certify and Oasis MCX. With one exception, all the studied drugs attained recoveries exceeding 50% for all columns. We considered the following drugs: amphetamine, amlodipine, chlorprothixene, fentanyl, haloperidol, ketobemidone, methadone, mirtazapine, olanzapine, quetiapine, sertraline and zopiclone. The average recoveries for the four column types ranged from 68.5% to 92.1% in the experiments. In conclusion, the basic compounds performed reasonably well in all columns, and other factors, such as availability and price, may be decisive in regard to choice of column.