STUDY OF FALSE POSITIVES IN TH CHEMICAL IDENTIFICATION OF MARIHUANA

• NCJ Number: 47274
• Journal: Journal of Forensic Sciences Volume: 23 Issue: 2 Dated: (APRIL 1978) Pages: 304-310
• Author(s): R B HUGHES; V J WARNER
• Date Published: 1978
• Length: 7 pages
• Corporate Author: American Soc for Testing and Materials
• Sale Source: US Drug Enforcement Administration
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

THE RELIABILITY OF THE MODIFIED DUQUENOIS-LEVINE TEST FOR THE IDENTIFICATION OF MARIHUANA WAS EXAMINED BY SUBJECTING 50 HERBAL SUBSTANCES TO BOTH THIN-LAYER CHROMATOGRAPHY AND THE MODIFIED VERSION OF THE TEST.

Abstract

HERBAL SUBSTANCES INCLUDED CHEMICAL, PLANT, OR ESSENTIAL OILS. PROCEDURE USED FOR THE MODIFIED DUQUENOIS-LEVINE TEST INVOLVED EVAPORATION OF TEST SUBSTANCE RESIDUE FROM A PETROLEUM ETHER SOLUTION. RESIDUE WAS THEN DISSOLVED IN DUQUENOIS REAGENT AND 1 ML HYDROCHLORIC ACID WAS ADDED. COLOR CHANGES WERE OBSERVED OVER A 2-MINUTE AND A 10-MINUTE TIME INTERVAL. AFTER 10 MINUTES, 1 ML CHLOROFORM WAS ADDED FOR COLOR TRANSFER TO THE CHLOROFORM LAYER. RESULTS OF THE THIN-LAYER CHROMATOGRAPH AND THE DUQUENOIS-LEVINE TEST FOR COMPOUNDS ANALYZED WERE COMPARED WITH RESULTS OBTAINED FOR CANNABINOL, TETRAHYDROCANNABINOL, AND CANNABIDIOL FOUND IN A MARIHUANA SAMPLE. A NUMBER OF THE SUBSTANCES TESTED PRODUCED POSSIBLY CONFUSING RESULTS. HOWEVER, ADDITION OF CHLOROFORM AT 2 MINUTES GREATLY INCREASES THE SELECTIVITY OF THE TEST AND THE POSSIBILITY OF FALSE POSITIVES BECOMES NEGLIGIBLE. ONLY A LIMITED NUMBER OF FRESH COFFEES MIGHT GIVE MISLEADING RESULTS WITH THE MODIFIED TEST. HOWEVER NONE OF THE COMPOUNDS OR MIXTURE OF COMPOUNDS TESTED WILL COINCIDENTALLY CHROMATOGRAPH AND DEVELOP THE SAME COLORS, AS MARIHUANA WHEN SPRAYED WITH FAST BLUE B SALT AFTER THIN-LAYER CHROMATOGRAPHY ANALYSIS. IT IS CONCLUDED THAT WHERE MORPHOLOGICAL STRUCTURES ARE NOT READILY OBSERVABLE, BOTH THE MODIFIED TEST AND THIN-LAYER CHROMATOGRAPHY MUST BE DONE TO IDENTIFY A SUBSTANCE AS HAVING ORIGINATED FROM THE CANNABIS PLANT. HOWEVER IF THE GLANDULAR, CLOTHING, AND UNICELLULAR CYSTOLITHIC HAIRS ARE PRESENT EITHER THE MODIFIED TEST OR CHROMATOGRAPHY WITH FAST BLUE B ARE POSITIVE EVIDENCE THAT CANNABIS IS PRESENT IN THE SAMPLE. SUBSTANCES TESTED AND TEST RESULTS ARE PRESENTED IN A TABLE, AND REFERENCES ARE INCLUDED. (JAP)