Therapeutic drug management
Trough levels are most reproducible
Dk green heparin (Li or Na), no gel
Immediatley following collection, mix sample thoroughly by gentle inverting 8 - 10 times, to prevent clotting
Refrigerated (preferred)
Ambient - 3 days
Frozen (OK)
Gel-barrier tubes are not recommended
Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)