Analyt: Cortisol
Matrix: Serum
Measuring Method: GC-ID/MS
Standard: Cortisol NIST 921
Internal Standard: Cortisol-d₂
Sample Processing: Samples are spiked gravimetrically with internal standard and equilibrated. They are made alkaline with aqueous KOH and extracted into dichloromethane. A "pre-clean" step is made with a Sephadex LH-20 column. Derivatisation is with acetone-HFBA and subsequent extraction into cyclohexane.
Measurement: Measurement at m/z 489 and m/z 491