Split Specimen

Division of a urine sample into two bottles (primary "A" and split "B") to allow the donor to request independent re-testing of a positive result.

Key Facts

  • Urine split into Bottle A (primary, 30 mL min) and Bottle B (split, 15 mL min)
  • Donor has 72 hours to request Bottle B re-analysis after a positive result
  • Bottle B sent to a different SAMHSA-certified laboratory
  • If Bottle B fails to confirm, the test is cancelled

Under DOT regulations, the urine specimen is split into two containers at the time of collection: Bottle A (primary, minimum 30 mL) and Bottle B (split, minimum 15 mL). Both are sent to the laboratory. If Bottle A tests positive, the donor has 72 hours to request that Bottle B be sent to a different SAMHSA-certified laboratory for re-analysis. If Bottle B fails to confirm the result, the test is reported as cancelled. This process protects donors from false-positive results.

Drug Testing Procedures Compared

Key procedural elements that ensure drug test integrity and accuracy.

TypeWhat It CoversRegulationKey RequirementIf Violated
Chain of CustodySpecimen tracking49 CFR Part 40Unbroken documentationTest may be invalidated
CCF FormCollection documentation49 CFR Part 40Multi-part form for all DOT testsTest cancelled
Split SpecimenRetest option49 CFR Part 40Bottle A (30 mL) + Bottle B (15 mL)Test cancelled if B negative
Cutoff LevelsPositive/negative thresholdSAMHSA guidelinesTwo-stage: screen then confirmFalse positives/negatives

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