title: Use of particle-loaded membranes to extract steroids for high-performance liquid chromatographic analyses improved analyte stability and detection.
abstract: Cortisol, cortisone, corticosterone, prednisone and prednisolone are extracted from serum using the novel particle-loaded octyl (C8)-bonded silica in PTFE membrane. Extracts are directly injected, without further concentration, onto a narrow (2.0 mm) or conventional (4.6 mm) bore octyldecyl (C18) HPLC column. Method performance data demonstrate linearity from 0.4 microgram/dl (low limit of detection) up to at least 60 micrograms/dl. Extraction recoveries exceeded 85% and precision (between-run) R.S.D.s averaged < 5%. Interferences were minimal and selectivity was improved over conventional immunochemical steroid assays. When compared to large particle sorbents packed in columns or to traditional liquid-liquid extractions, the membrane extracted steroids in less time, used less reagent, and had smaller elution volumes, thereby obviating steroid instability/adsorption problems associated with traditional concentrating techniques required to improve analytical sensitivity.
authors.affiliation: Clinical Toxicology/Special Chemistry Laboratory, University of Wisconsin Hospital and Clinics, Madison 53792.
authors.forename: G L
authors.initials: GL
authors.lastname: Lensmeyer
authors.forename: C
authors.initials: C
authors.lastname: Onsager
authors.forename: I H
authors.initials: IH
authors.lastname: Carlson
authors.forename: D A
authors.initials: DA
authors.lastname: Wiebe
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods* / Q000706:statistics & numerical data; D003345:Corticosterone / Q000097:blood; D003348:Cortisone / Q000097:blood; D004355:Drug Stability; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008567:Membranes, Artificial; D011239:Prednisolone / Q000097:blood; D011241:Prednisone / Q000097:blood; D012680:Sensitivity and Specificity
chemical_list: D008567:Membranes, Artificial; D011239:Prednisolone; D003348:Cortisone; D011241:Prednisone; D003345:Corticosterone; D006854:Hydrocortisone