The application of fully automated on-line solid phase extraction in bioanalysis

This paper describes the application of fully automated on-line solid phase extraction to the bioanalysis of three example compounds using the Symbiosis platform. The on-line assay performance is compared to off-line methodologies for the same compounds. The three example compounds possess a variety of physicochemical properties and different extraction modes were applied in off-line methods. These methods were developed through optimisation of solid phase or liquid–liquid extraction and chromatographic separation conditions for each of the analytes. Both on-line and off-line methods were evaluated for linearity, carryover, imprecision and inaccuracy. Experiments were also performed investigating modification of ionisation and selectivity against different batches of plasma. On-line and off-line methods were found to be comparable in performance. In conclusion, on-line methodology has distinct advantages for the analysis of large numbers of samples with a marked reduction in manual operation.