Therapeutic drug management
Trough levels are most reproducible
Dk green heparin (Li or Na), no gel
Immediately following collection, mix by inverting 8 - 10 times to prevent clotting
Refrigerated (preferred)
Ambient (OK) - 3 days
Frozen (OK)
Gel-barrier tubes are not recommended
Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
800 - 1600 ng/mL