Table 1.

Detection rates and percentage of patches positive for MDMA and MDA in sweat patches during and after MDMA administration and in washout sweat patches at the limits of quantification and proposed SAMHSA cutoffs (25 ng/patch). LOQs were 2.5 ng/patch for MDMA and 5 ng/patch for MDA.

Total patches (N = 559)	MDMA	MDA	MDMA only	MDA only	MDMA & MDA	Total
LOQ (ng/patch)	2.5	5
≥LOQ	360	174	196	10	164	370
Positive, %	64.4	31.1	35.1	1.8	29.3	66.2
Range, ng/patch	2.5−3007.7	5.0−171.2	2.5−346.6	5.8−41.1
≥SAMHSA cutoff (25 ng/patch)	217	58	162	3	55	220
SAMHSA positive, %	38.8	10.4	29	0.5	89.8	39.4
Washout patches (n = 81)	MDMA	MDA	MDMA only	MDA only	MDMA & MDA	Total
≥LOQ	22	14	13	5	9	27
% Positive, %	27.2	17.3	16	9.8	11.1	33.3
Range, ng/patch	2.6−287.2	6.4−31.7	2.6−25.7	9.2−20.4
≥SAMHSA cutoff (25 ng/patch)	7	2	1	6	1	8
SAMHSA positive, %	8.6	2.5	1.2	7.4	1.2	9.9