Quantitative in situ fluorometry of LSD by HPTLC

Sections

Introduction
Method
Extraction
Chromatography
Measurement
Results
Acknowledgement
Bibliography

Details

Author: L. KRAUS , E. STAHL , W. THIES
Pages: 67 to 72
Creation Date: 1980/01/01

Quantitative in situ fluorometry of LSD by HPTLC

L. KRAUS Department of Pharmacognosy, Hamburg University, Hamburg,Federal Republic of Germany
E. STAHL Department of Pharmacognosy, Hamburg University, Hamburg,Federal Republic of Germany
W. THIES * Hamburg University, Hamburg, Federal Republic of Germany

Introduction

Lysergic acid diethylamide (LSD) is found on the illicit market often absorbed by substances such as sugar cubes, blotting paper, felt strips, cigarette paper, or in the form of tablets and dragées, or mixed with lemonade. LSD can be relatively easily synthesized from ergot alkaloids in small laboratories.

The principal effect of LSD is reported to be the loss of the sense of reality. The effect of LSD is dose-related. Doses as low as 20-25 μg may be capable of producing an effect. Street samples are often adulterated, which augments the risk of users. The user is usually not in a position to know anything about chemical purity of a street sample. Considering these facts, it is important to know the grade of chemical purity and the variation of dose in illicit street samples of LSD.

Method

In 1971 and 1976 Niwaguchi and Inoue described a method for the quantitative determination of LSD in situ. The smallest detectable amount quoted by the authors was 0.1 μg and the relative standard deviation was 0.2-6.7 per cent when scanning quantities of 0.2-2.0 μg. Using HPTLC-layers (High Performance Thin Layer Chromatography) and the material and apparatus conditions listed below, we found that LSD can be determined in amounts of about 0.01 μg with a relative standard deviation of 2-4 per cent, and could be detected at a level as low as 0.002 μg.

Extraction

The felt strips were well grounded in a mortar with sea-sand and transferred into a mini-column (fig. 1). Eight ml methanol were necessary to elute the LSD and this volume was made up to 10 ml. Two μ1 of this solution, corresponding to 0.01 μg of LSD based on the assumption that a strip contains 50 μg of LSD, were spotted with microcaps (Drummont) on the HPTLC.

* Part of dissertation: The analysis of illegal LSD preparations, Hamburg, 1978.

MINI-COLUMN

Figure 1

TLC of LSD in felt strips

Full size image: 11 kB, Figure 1

Conditions: HPTLC Silica Gel 60 plates 10 x 10 cm Merck Ethanol (absolute)-chloroform (75:25)

Chromatography

Stationary phase: HPTLC plates precoated with Silica Gel 60 (Merck) 10 x 10 cm

Solvent system: Ethanol (absolute)-chloroform (75:25)

Solvent front: 6 cm

Spotting: 2 μl of methanol extract

2 μl standard solution (external standard) of 0.5 μg LSD in

100 ml of methanol corresponding to 0.01 μg LSD.

Each plate was spotted with four samples (twice each) and two standard solutions (fig. 2)

Figure 2

Mini-column for extraction of LSD

Full size image: 9 kB, Figure 2

Figure 3

Relationship between fluorescence emission intensity and amount of LSD

Full size image: 20 kB, Figure 3

Measurement

Apparatus slit width multiplier position wave-length

Spectrophotometer for TLC, Zeiss PMQ II

8 x 0.2 mm

8/10/I/A

Excitation 313 nm (Hg)

Emission 420 nm

Considering the fast photodecomposition of LSD, we spotted an additional standard solution spot on the border of the plate in order to find out the best position for the slit. The scanning direction was perpendicular to the chromatographic flow.

Figure 4

Statistics of LSD contents in felt strip

Full size image: 18 kB, Figure 4

Measurements: n = 100

Mean value: x = 47.5 µg

Standard deviation: s = 10.8 µg

Variation: v = 22.7 per cent

Results

The statistical evaluation of LSD content in 100 felt strips (one charge) is shown in figure 4. The mean value was established to be 47.5 μg per strip with the standard deviation of 10.8 μg, corresponding to a variation of 22.7 per cent; 72 per cent of the samples was found inside and 28 per cent outside of the standard deviation. The absolute amount of LSD in these felt strips varied between 20 and 80 μg per strip.

Acknowledgement

The authors are grateful to Merck, Darmstadt, for providing the HPTLC precoated Silica Gel 60 plates.

Bibliography

Niwaguchi, T., and T. Inoue. Direct quantitative analysis of lysergic acid diethylamide and 2,5-dimethoxy-4-methylamphetamine on thin-layer chromatograms. Journal of Chromatography (Amsterdam), 121: 165, 1976

Studies on quantitative in situ fluorometry of lysergic acid diethylamide (LSD) on thin-layer chromatograms. Journal of Chromatography (Amsterdam), 59:127, 1971.