Journal of Analytical Toxicology
October 1, 1998
Zhi Li, A. J. Mcnally, Honggang Wang et al.
50 citations
LSD in pooled urine is stable for up to 4 weeks at 25 degrees C in the dark, with no significant loss. At 37 degrees C, a 30% loss occurred after 4 weeks, and up to 40% at 45 degrees C. Amber glass or nontransparent polyethylene containers preserved LSD concentration under any light conditions; stability in transparent containers depended on distance from light source, wavelength, exposure time, and intensity. Prolonged heat in alkaline pH converted 10 to 15% of LSD to iso-LSD; under acidic conditions, less than 5% converted. Trace metal ions catalyzed decomposition, preventable by adding EDTA. Proper storage is essential for accurate analytical testing.
Journal of Analytical Toxicology
October 1, 1997
S. J. Salamone, Z. Li, A. J. Mcnally et al.
23 citations
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.
Journal of Analytical Toxicology
October 1, 1996
A. J. Mcnally, K. Goc-Szkutnicka, Z. Li et al.
17 citations
A new homogenous microparticle-based immunoassay (Abuscreen OnLine) detects LSD in human urine at a cutoff of 0.5 ng/mL, matching the sensitivity of the existing Abuscreen RIA. All 31 samples previously confirmed positive by gas chromatography-mass spectrometry also tested positive with both the OnLine and RIA assays. Among 1,000 presumed negative samples, 992 (99.2%) were negative; the 8 OnLine positives were negative by RIA. The assay shows greater than 35% cross-reactivity to nor-LSD and similar cross-reactivity to other related compounds as the RIA. Within-run precision was less than 2.5% and between-run precision less than 3.0%.
Bioconjugate Chemistry
November 1, 1997
Zhuyin Li, K. Goc-Szkutnicka, A. J. Mcnally et al.
13 citations
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.