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Thyroxine

Analyt: Thyroxine
Matrix: Serum
Measuring Method: GC-ID/MS
Standard: Supelco/Cerilliant T-073-1ML
Internal Standard: ¹³C₆-L-Thyroxine in protein solution - custom synthesis
Sample Processing: The samples are gravimetrically spiked with internal standard and equilibrated, then precipitated with acetone HCl and extracted with ethyl acetate. Derivatization (methylation) is carried out with methanolic HCl, followed by HFBA in tetrahydrofuran and extraction with cyclohexane.
Measurement: Measurement at m/z 773 and m/z 779 and m/z 970 and m/z 976