Lysergic acid diethylamide（LSD）analogues are emerging psychoactive substances; some are suspected to act as in vivo prodrugs. As a preliminar y step toward evaluating this potential, we compared conventional liquidliquid extraction（LLE）method with a micro-volume QuEChERS method for screening LSD, 1cP-LSD, 1V-LSD, and 1T-LSD in mouse pool serum. Each drug （2 or 10 ng/ mL spiked to mouse serum） was spiked before and after extraction, and measured by LC-MS/MS. Both methods yielded higher recoveries at 10 ng/mL（LLE：74.3-101.2％, QuEChERS：88.5-91.3％） than at 2 ng/mL （LLE：56.1- 104.3％, QuEChERS：67.4-93.7％）, with 1V-LSD being consistently the lowest. QuEChERS showed lower variability and better 1V-LSD recovery than those of LLE. This is the first application of micro-volume QuEChERS to LSD analogue extraction from biological samples, indicating it as a promising alter native for screening postadministration serum and supporting future studies on metabolic fate and prodrug properties.
