Specimens that can be tested: serum, saliva, sweat, urine, hair
Methods: liquid chromatography-mass spectroscopy (LC/MS), tandem MS
Limit of detection: around 40 ng/mL (0.1 µg/mL = 100 ng/mL)
Recovery is approximately 0.04% (standard deviation 0.02%, +/- 2SD would be 0.00% to 0.08%) of administered ethanol dose (Goll et al).
Detection limits:
(1) serum: up to 36 hours
(2) urine: up to 5 days
The cutoff used to call a positive test varies. A low cutoff (100 ng/mL) is sensitive but may not be specific. A higher level (500 ng/mL) is more specific but will reduce the detection window.
A person who has ingested a significant amount of alcohol will have a urine value of ethyl glucuronide in the thousands or tens of thousands per mL for the first 24 to 48 hours after the exposure.
Minor exposures to ethanol (in mouthwash, medicines, etc) can result in minor elevations in urine levels, usually < 100 ng/mL.
Measurement of urine creatinine can be used to detect a diluted sample, with a urine creatinine < 25 mg/dL indicating a dilute sample. Dilution may be done deliberately; it may also be due to a physiologic or pathologic state. This is discussed further in Chapter 32.
