Laboratory Testing Cutoffs & Methods

• Screening Cutoff Levels and Methods
• Confirmation Cutoff Levels and Methods
• Oral Fluid Detection Times

Overview

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).

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).