Zolpidem urine test method change. 05/28/13

Effective May 28, 2013, Redwood Toxicology Laboratory will start confirmation testing of urine Zolpidem and its metabolite, carboxyzolpidem, using the industry's most advanced, most sensitive and specific analytical method, liquid chromatography/ tandem mass spectrometry (LC/MS/MS)

Specificity of LC/MS/MS can be attributed to the fact that it separates the parent mass of the analyte and further breaks it down into fragments that are specific to the analyte, known as multiple reaction monitoring (MRM), ensuring that the peak is the analyte we seek, and that background interference is minimal.

All presumptive positive specimens will be confirmed by this highly sensitive and specific analytical method allowing for very low level detection of zolpidem in urine. The cutoff for zolpidem will be 1 ng/mL, and carboxyzolpidem at 10 ng/mL. If you have any questions, please contact Toxicology Support Services at: 800.255.2159, press option 5.

Specimen Type


Test Name

Zolpidem Urine Test (Quantitative)

Test Method

Liquid Chromatography / Tandem Mass Spectrometry (LC/MS/MS)

Redwood Toxicology Laboratory

11 000 3466 REV1


Media Contact

800-255-2159 ext 34360
Send an Email