Immunoaffinity in-tube solid phase microextraction coupled with liquid chromatography with fluorescence detection for determination of interferon α in plasma samples

The present work describes a sensitive and specific automated immunoaffinity in-tube solid-phase microextraction coupled with liquid chromatography with fluorescence detection (LC-FD) method for the determination of interferon alpha(2a) in plasma samples for therapeutic drug monitoring. To this end, the intrinsic selectivity of the monoclonal antibodies has been combined with in-tube solid phase microextraction by immobilization of these antibodies into the fused silica capillary. The in-tube SPME variables, such as plasma sample volume, draw/eject volume, number of draw-eject cycles, as well as desorption procedure have been optimized, in order to improve the sensitivity of the proposed method. Analyses of interferon alpha(2a) in plasma samples were carried out within 12 min (sample preparation and LC analyses). The response of the proposed method was linear over a dynamic range 0.006-3.0 MIU mL(-1), with a correlation coefficient of 0.998. The inter-day precision of the method had a coefficient of variation lower than 6.2%. The proposed automated method has adequate analytical sensitivity and selectivity for the determination of interferon alpha(2a) in plasma samples for therapeutic drug monitoring. The proposed method was successfully applied to the plasmas samples analyses from patients in therapy with interferon alpha-2a, demonstrating a rare application of in-tube SPME for biopharmaceutical (protein) analyses. (C) 2013 Elsevier B.V. All rights reserved.