Table 3.

Detection times for immunoassay and chromatography

DRUG	NUMBER OF DAYS DRUG IS DETECTABLE
	IMMUNOASSAY	CHROMATOGRAPHY
Benzodiazepines (regular use)	20 d or more for regular diazepam use Immunoassay does not distinguish among benzodiazepines Intermediate-acting benzodiazepines, such as clonazepam, are often undetected	Not usually used for benzodiazepines
Cannabis	20 d or more	Not used for cannabis
Cocaine and metabolites	3–7 d	1–2 d
Codeine	2–5 d	1–2 d (codeine metabolized to morphine)
Hydrocodone	2–5 d	1–2 d
Hydromorphone	2–5 d	1–2 d
Meperidine	1 d (often missed)	1 d
Morphine	2–5 d	1–2 d; morphine can be metabolized to hydromorphone
Oxycodone	Often missed	1–2 d

Adapted from Brands and Brands.¹³