Laboratory Testing Cutoffs & Methods


Oral fluid testing is gaining popularity with many programs that require convenient, gender-neutral specimen collection combined with the accuracy of lab testing. RTL provides an easy and affordable lab-based testing solution for the detection of drugs of abuse in oral fluid.

Oral fluid drug testing from RTL utilizes the only collection device that has a volume adequacy indicator. This indicator ensures that sufficient saliva (1 mL) is collected to prevent possible false negative results due to insufficient sample size, and to provide a meaningful quantitative result.

The oral fluid collection device also allows drug concentrations to be reported per mL of oral fluid (GC-MS & LC-MS/MS confirmations only). One (1) mL of oral fluid combined with three (3) mL of buffering agent provides four (4) mL of specimen, allowing a sufficient amount of sample for screening and confirmation procedures.

The following is an explanation of RTL's oral fluid screening and confirmation procedures/cutoff levels. The routine cutoff levels listed below may periodically change. Note: some cutoff levels may differ for your agency.

Saliva Screening Methodology

Specimens collected with the oral fluid collection device are sent to Redwood Toxicology Laboratory for screening by Enzyme Immunoassay (EIA) or Enzyme-Linked Immunosorbent Assay (ELISA).

Screening Cutoff levels by EIA —Cutoff levels updated periodically.
Drugs of Abuse EIA Cutoff
.025 g/dL
50 ng/mL
Barbiturates 50 ng/mL
Benzodiazepines 20 ng/mL
Buprenorphine 5 ng/mL
Cocaine Metabolite (Benzoylecgonine) 20 ng/mL
Methadone 50 ng/mL
Methamphetamine 50 ng/mL
Opiates (Codeine, Hydrocodone, Hydromorphone, 6-MAM, & Morphine) 40 ng/mL
Oxycodone 40 ng/mL
Phencyclidine 10 ng/mL
THC (cannabinoids) 4 ng/mL
Tramadol 50 ng/mL

Oral Fluid Drug Test Confirmation Methodology

Positive screens are confirmed by gas chromatography—flame ionization detector (GC-FID) gas chromatography/mass spectrometry (GC-MS) or Liquid chromatography/tandem mass spectrometry (LC-MS/MS).

Confirmation Cutoff Levels by Methdology —Cutoff Levels Updated Periodically
Drugs of Abuse Methodology Cutoff
GC-FID .025 g/dL
LC-MS/MS 15 ng/mL
Barbiturates GC-MS 25 ng/mL
Pentobarbital GC-MS 20 ng/mL
   - Alprazolam, Chlordiazepoxide, Clonazepam,
     Diazepam, Flunitrazepam, Flurazepam,
     Lorazepam, Miazolam, Nordiazepam,
     Oxazepam, Temazepam, Triazolam
LC-MS/MS .5 ng/mL
Buprenorphine LC-MS/MS 1 ng/mL
Norbuprenorphine LC-MS/MS 5 ng/mL
Cocaine Metabolite (Benzoylecgonine) LC-MS/MS 4 ng/mL
Methadone LC-MS/MS 10 ng/mL
Methamphetamine GC-MS 15 ng/mL
   - Codeine, Hydrocodone,
    Hydromorphone, Morphine
   - 6-monoacetylmorphine



8 ng/mL

4 ng/mL
Oxycodone / Oxymorphone LC-MS/MS 8 ng/mL
Phencyclidine GC-MS 5 ng/mL
THC (cannabinoids) GC-MS 1 ng/mL
Tramadol LC-MS/MS 5 ng/mL

Oral Fluid Detection Times1
Drugs of Abuse Detection Time
After absorption (~1 hour) blood alcohol decreases ~.02 gm%/hour
From minutes up to 48 hours
Barbiturates From minutes up to 48 hours
Benzodiazepines From minutes up to 48 hours
Methamphetamine From minutes up to 48 hours
Cocaine From minutes up to 48 hours
Opiates From minutes up to 48 hours
Oxycodone From minutes up to 48 hours
Phencyclidine From minutes up to 48 hours
THC (Δ - 9 THC) From minutes up to 48 hours
Methadone From minutes up to 48 hours

To learn more about RTL's laboratory drug tests call:


  1. Average detection time. Chronic exposure may lead to longer detection times

Contact Us

Laboratory: 800-255-2159

Products: 877-444-0049