Liquid chromatography/tandem mass spectrometry (LC-MS/MS
Rejection Criteria
Samples collected in serum separator tube
Reference Range(s)
10.0-35.0 mcg/mL
Specimen Requirements
Preferred Specimen
Plain Red Top Tube
Minimum Volume
0.2 mL serum or plasma
Sample Stability
3 days room temperature 10 days refrigerated 1 month frozen
Transport Temperature
Refrigerated
Collection Instructions
Ideal sampling time for all antiepileptic drugs is
immediately before the next oral dose (trough). If this is
not possible, patients should not be advised to delay their
scheduled dose for longer than 2-3 hours. Sample collection
and the time that the medication was last ingested should be
noted on the requisition.
Alternative Specimen
1 mL EDTA (lavender top) or sodium fluoride/potassium
oxalate (gray top) plasma. Centrifuge sample and separate
plasma from cells immediately. Transfer plasma to a plastic
transport tube. Clearly label tube as EDTA or fluoride
plasma. Refrigerate