Samples and concentrations:
(1) urine: results express in ng/L or ng/mL
(2) blood: results may be expressed in ng/mL, ng/L or ng per gram sample (mass per mass units). In post-mortem samples decomposition may affect the fluidity of the sample, so that mass is a more reliable measure
6-acetylmorphine (6-AM):
(1) specific metabolite of heroin present in both blood and urine
(2) half-life in blood is 10-20 minutes, so below detection limits by 2 hours after administration
(3) detectable in the urine for a longer period of time
ratio of morphine-to-codeine =
= (concentration of morphine) / (concentration of codeine)
Interpretation:
• A ratio of morphine to codeine > 1 is seen in persons who have used heroin.
• A ratio <= 1 is seen in a person taking codeine.
Criteria for heroin use:
(1) urine opiate concentration >= 2,000 ng/mL (2.0 ng/L), according to the SAMHSA limit (the SAMHSA limit was raised from >= 300 ng/mL in 1998)
(2) 6-AM present and/or ratio of morphine to codeine > 1
where:
• The cutoff for 6-acetylmorphine in the urine is often set to >= 10 ng/mL.
