Comparative Study of Different Solid-Phase Extraction Cartridges in the Simultaneous RP-HPLC Analysis of Morphine and Codeine in Biological Fluids

Abstract

A comparative study of different Solid-Phase Extraction (SPE) Cartridges for the extraction and purification of morphine and codeine in plasma and urine samples is presented. A rapid and sensitive Reversed-Phase isocratic High-Performance Liquid Chromatographic (RP-HPLC) method has been developed for the simultaneous determination of morphine and codeine in plasma and urine samples, using quinine as internal standard. The drugs were extracted from the sample matrices by using the SPE technique and a series of cartridges from different manufacturers and with different sorbents were tested. The best recover)' from plasma was achieved with Alltech C'8 cartridges and the best recovery from urine with Bakerbond C18 cartridges. The HPLC analysis was performed with an Adsorbosphere HS C18, ODS, 5 pm. 250 × 4.6 mm I. D., column and UV detection at 241 nm and it was completed within approximately 10 min. The mobile phase was a mixture of methanol-acetonitrile 0.1 M ammonium acetate (40 : 25 : 35 v/v) and the flow rate was 0.80 ml /min. The detection limits were found to be 2.0 ng on-column for morphine and 1.0 ng on-column for codeine.