title: A reference method for the analysis of aldosterone in blood by high-performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry.
abstract: A high-performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (HPLC-APCI-MS/MS) reference method for the quantitation of aldosterone in serum and plasma has been developed. Samples were extracted with dichloromethane/diethyl ether, containing flumethasone as internal standard (IS). Chromatography was performed on a phenyl column using 50 mm ammonium formate (pH 7.1)/methanol (50/50, v/v) as mobile phase. Analysis was in negative-ionization mode by selected reaction monitoring (aldosterone m/z 359.2 --> 331.2; IS m/z 455.0 --> 379.0). The assay was linear over the range 15-500 pg/mL, with limits of detection and quantitation of 10 and 15 pg/mL, respectively. Imprecisions of the assay at 15, 20, 150, and 450 pg/mL were 18.5, 8. 8, 10.6, and 9.5%, respectively. The accuracy of the method ranged from 93.1 to 98.9% with absolute recoveries between 84.0 and 91.3% (aldosterone) and 88.0 and 92.3% (IS). We present a case study of a patient admitted, with suspected primary hyperaldosteronism, on the basis of a high radioimmunoassay (RIA) aldosterone concentration. The results suggest that RIA was unreliable, causing unnecessary patient discomfort and a costly 6-day hospital stay. The specific HPLC-API-MS/MS assay described offers the sensitivity and accuracy required to assess abnormal aldosterone production in hypertensive patients.
authors.affiliation: Department of Clinical Pharmacology, Princess Alexandra Hospital, Brisbane, Queensland, 4102, Australia. Fredline@gpo.pa.uq.edu.au
authors.forename: V F
authors.initials: VF
authors.lastname: Fredline
authors.forename: P J
authors.initials: PJ
authors.lastname: Taylor
authors.forename: H M
authors.initials: HM
authors.lastname: Dodds
authors.forename: A G
authors.initials: AG
authors.lastname: Johnson
mesh_terms: D000450:Aldosterone / Q000097:blood*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D011863:Radioimmunoassay
chemical_list: D000450:Aldosterone