Preliminary Evaluation of the Asted XL Dialysis System Towards its Applicability In Ligand Binding Assays

Abstract

Abstract In ligand binding assays, the separation of bound and free fraction of the labeled ligand is very important. Dialysis is generally overlooked as separation technique since it requires large volumes and long analysis times. The availability of the ASTED-system (Automated Sequential Trace Enrichment of Dialysates) might open ways for a complete automation of immuno assays including the separation step. A well-documented radio-immuno assay for 3-keto-desogestrel (Org3236) was used to test the potentials of this system. The tritiated analog of Org3236 not only served as label in the immuno assay but was also used to trace this compound in the entire procedure. The dialysis efficiency increased with the dialysis time and with the flush rate of the recipient solvent (tris-HCI or phosphate buffer). Addition of methanol to recipient solvent had spectacular effects on the recovery. With tris-HCI buffer, 0.18 mL/min and 1.0 mL recipient solvent 2.5% of the label was collected. Addition of 50% methanol resu...