A fully automated method for sample clean-up prior to chromatographic and immunological analysis

A fully automated technique for the extraction and clean-up of low-molecular weight analytes from human serum and urine is presented. Its efficiency for sample clean-up prior to immunological assay is demonstrated for six adrenal and gonadal steroid hormones, calcidiol and the peptide hormones gastrin, insulin and glucagon. A more intensive sample clean-up, which is mandatory for liquid chromatographic analysis, is reported for serum cortisol. With the exception of calcidiol, the extraction of steroids is almost complete. Recovery of peptides is about 80% and depends on the nature of the peptide and on protein-analyte dissociating diluents. Precision of recovery is lower than 7% (CV) for all analytes studied. One hundred serum or urine samples can be cleaned up without loss of efficiency by only one solid-phase cartridge. The technique is in principle applicable to all other analytes with physico-chemical structures similar to the analytes in the present study.