Differential Identification of Six “Mystery” Substances Using Three Distinct Analytical Techniques in a Forensic Science Laboratory

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 21 (2016) pp 115-118

Differential Identification of Six “Mystery” Substances Using Three Distinct Analytical Techniques in a Forensic Science Laboratory

Jenna Cote, Leora Hilbert and Sulekha Rao Coticone*

Department of Chemistry and Physics, Florida Gulf Coast University, Ft Myers, FL 33965, scoticon@fgcu.edu
Received January 12, 2016. Accepted May 25, 2016.

Published: 20 June 2016

Abstract. It is widely known that active learning exercises in analytical chemistry that are used to solve real life problems can stimulate student interest. A specific area that stimulates student interest is the application of analytical chemistry in the field of forensic science. Based on the growing interest in forensic science, this laboratory utilizes three analytical techniques to identify six unknown compounds. In the present exercise, students learn to apply presumptive, mid-level, and confirmatory tests to identify six unknown over the counter (OTC) drugs (Aspirin, Aleve, Diphenhydramine, Caffeine, Lidocaine and Pseudoephedrine). These drugs were chosen based on their ease of acquisition and ability to mimic illicit substances when these tests are performed. Two different color spot tests (Cobalt thiocyanate and Marquis) are used for presumptive testing. The OTC drugs are dissolved in a range of solvents for thin layer chromatography (TLC) analysis to narrow down the possible identities of the drugs. Finally, using Nuclear Magnetic Resonance (NMR) to obtain the organic structures of the unknown drugs, students are able to conclusively identify the drugs.

Key Words: Laboratories and Demonstrations; analytical chemistry; forensic, active learning, analytical techniques, color spot tests, thin layer chromatography, Nuclear Magnetic Resonance

(*) Corresponding author. (E-mail: scoticon@fgcu.edu )

Article in PDF format (159 KB) HTML format

Supporting Materials:

Instructor notes, student handout, example spot tests, TLC data and NMR spectra are supplied. (481 KB)