Red serum vial/tube, 5 mL

• Trough: Collect immediately prior to next dose
• Immediately following collection, mix by inverting 8 - 10 times to prevent clotting

1. Allow sample to clot
2. Spin within two (2) hours of sample collection
3. Transfer serum to a Serum/plasma transfer vial/tube (MedTox), labelled as serum

Serum/plasma transfer vial/tube (MedTox)

Dk green heparin (Li or Na), no gel

Immediately following collection, mix sample by inverting 5 - 10 times to prevent clotting.

1. Spin within two (2) hours of sample collection
2. Transfer serum to a Serum/plasma transfer vial/tube (MedTox), labelled as the appropriate plasma type

Ambient (preferred) - 3 days

Refrigerated - 2 weeks

Frozen - 2 weeks

Gel-barrier tubes are not recommended

Liquid chromatography/tandem mass spectrometry (LC/MS-MS)

Fentanyl: 1 - 3 ng/mL

Fentanyl threshold: 0.1 ng/mL
Norfentanyl threshold: 2.5 ng/mL

Medical necessity