LSD converts to its epimer iso-LSD at temperatures above 37 °C and pH levels over 7.0. At pH 7.0 or higher, a 9:1 ratio of LSD to iso-LSD is reached after one week at 45 °C or two weeks at 37 °C. Starting from iso-LSD, achieving the same 9:1 ratio requires six weeks at 45 °C and pH 9.7, indicating more vigorous conditions are needed. This ratio represents an equilibrium concentration with an equilibrium constant K = 9. The study used proton NMR to follow the reaction by integrating the C-9 resonances of LSD and iso-LSD, appearing as singlets at 6.35 and 6.27 ppm respectively. This is the first quantitative measurement of LSD epimerization by NMR.
Three lysergic acid diethylamide (LSD) derivatives were synthesized and characterized. The most stable derivative was selected and covalently linked to polystyrene microparticles through a carrier protein. Two new LSD immunogens were synthesized, generating antibodies that recognize LSD and several major LSD metabolites. A homogeneous microparticle-based immunoassay was developed for detecting LSD in human urine with sufficient sensitivity and specificity for effective screening. The assay's performance was evaluated using precision, cross-reactivity, correlation to the Abuscreen LSD RIA and GC/MS/MS, specificity, and limit of detection.