Forensic Drug Chemistry: A Cooperative Program Bruce A. Siggins United States Army Criminal Investigation Laboratory-Pacific, APO San Francisco, CA96343 Bobby W. Hendricks Zama American High School, Camp Zama, Japan Chemistry is inherently a "hands-on" science. Students are much more fascinated by what happens out the window than on the chalkboard, because most students are "concrete operational". They can reason with what they see concretely before them much better than with concepts in the mind. This naDer discusses a coonerative nromam in forensic chemisij between the 1J.S. k m y ~ r i k i i a Investigation l Laboratom-Pacific rUSACIIrPacific, and the Zama American ~ i g hSchool designed to link concepts of logical thoueht and chemical reasonine to the excitement of working l&oratory problems not or&arily encountered in high school. The nroblems were desiened to demonstrate to the students t h k they have sumcl'ent powers of observation and reasoning to arrive at a conclusion useful in forensic science. The close proximity (about 5 min by bus) of the Zama American High School to USACIL-Pacific made it easy to transport materials to the high school for use, and to transport small groups of students to the crime laboratory during their normal class period to use nonportable equipment. The program was developed as a "stand alone" module for presentation late in the school year, when students are somewhat familiar with handling chemicals and general laboratory safety requirements. The program was presented in a "visiting professor" format, with the classroom instructor amplifying and clarifying material covered in the program as it progressed. The entire program was spread into the class schedule over a three-week period, so as to not interrupt but augment the class's normal learning program. Learning Objectives Students have the opportunity to emulate the everyday activities of u forensic chemist: eatherine information and making basic observations ( ~ G e r i m e n I), i carrying out screening tests to narrow the field of the possible number and type of drug substances present in an exhibit (Experiment 21, and isolating and identifying the active drug component of interest (Experiment 3). A problem set was used to reinforce the concept of using chemical properties as tools to isolate and identify a substance, that is, chemical properties as problem-solvingtools in the hands of a chemist. Program Organization The program consisted of six phases: 1. Initial Lecture (One class ieriod) 2. Experiment 1: Observation and Information Collection
(One class period)
3. Experiment 2: Color Test and Thin-Layer Chmmatography (One class period) 4. Experiment 3: Isolation and Identification with Infrared Spectroscopy (One third of each class over three days) 5. Prohlem Set: Solving Forensic Pmblems 6. Final Lecture (Aportion of one class period)
312
Journal of Chemical Education
Before each experiment, the students were given a handout explaining the concepts involved and providing background information on the topic. On the day of the experiment a specific set of directions for lab groups to follow was provided. Safety Issues The laboratory procedures duplicate as closely as possible those actually in use in the field of criminal investigation. As such, small quantities of organic solvents (chloroform and methanol). ., mineral acids (sulfuric and hydrochloric), and organic and inorganic compounds reouirine careful handline are used. The auantities used are minimized by using microscale techniques; that is, only a dmp to a few milliliters were used in a given procedure. Students were advised of the safety precautions to be followed in the initial lecture. Suggestions for alternatives in the procedures-to adapt them to situations where some of the reagents that were used are banned for safety reasons or when the equipment used may not be available--are included below in the experimental outlines. In some cases the reagents used cannot be easily changed because these have been found in practical use to be the best for the work.
-
-
Initial Lecture The initial lecture covered laboratory safety, the Army Criminal Investigation Laboratory system and its capabilities. an outline of a forensic chemist's duties. and an overview of the laboratory program to fbllow.The initial lecture also included a student handout with a "decision flow sheet" on drug analysis. This gave the students general background information on how laboratory drug case work proceeds, and how their experiments would fit in the overall procedure. Experiment 1. Observation and lnformatlon Collection Using pertinent literature (1-6)in forensic drug chemistry (including, to the students' surprise, the dictionary), students answered questions covering typical forensic terminology, chemical properties, separation methods, ingredients to be found in drug preparations, and legal control of drug substances (see Table 1). The needed references were placed in the classroom for student use. While the students were working on these questions, groups of two were called to work with a set of 5-30 variable power stereomicroscopes. They were given samples of vegetable matter (parsley,basil, tarragon, and cumin) and were asked to observe leaf characteristics, and then identify an unknown vegetable sample. Students quickly found that they could recognize and remember fine detail observed from the vegetable samples and correctly identify a n unknown sample. A sample of marihuana specially sealed for security was provided for student observation of the leaf characteristics used in part of its forensic identification. Additionally, they were given samples containing mixtures of crystals (salt, sucrose, and benzocaine) and asked
Table 1. Questions for Literature Review 1. What is an emetic?
2. What is the chemical formula for methamphetamine? 3. Draw the chemical structure of wcaine. 4. What are the principal ingredients of Damon?
How would you extract acetaminophen from a tablet? What is the molecular weight of sewbarbital? What Schedule of Control does amobarbital appear on? What does it mean when someone says a drug is listed on Schedule I of the Public Law? 9. Name a drug product manufactured by Eli Lilly company. 10. Find a commercial product that contains lidocaine or lidocaine hydrochloride. 11. What is a diuretic? 5. 6. 7. 8.
to identify the number of components possibly present by observing the different types of crystals observed in the mixture. Although initially lacking confidence in their ability to make identifications of crystal forms, with practice students achieved a high success rate in identifyirig the number of crystal components in the powder mixtures. Alternatives
The microscopes used in a biology class may be substituted if thev have a low enoueh Dower settine (30X is a good setting,, but the narrow fileldof view can make identification difficult. It i~ better to use a ~owerfulmamifvine glass on the vegetable material, so students can & overview of the entire leaf structure as well as details for identification. Numerous crystalline materials can be substituted in this experiment. The literature used (1-6)should be available in a library If sufficient copies of the entire work cannot be obtained, extracts should be used (after obtaining the authors /publishers uermission to reuroduce). The kev is to have students using literature (tkxts, magazine articles, etc.) that introduce them to conceuts and information used in solving real chemical in a specificfield of chemistryin this case -forensic chemistry. Experiment 2. Color Tests and Thin-Layer Chromatography
Experiment 2 allows students to work with small quantities of drug substances (specially diluted to reduce the risk of student misuse) and to use several chemical test reagents commonly utilized by police officers to screen suspected drug substances. Each two-student team would obtain a vial containing each of the known substances listed in Table 2 above. They would then run the color tests using a small amount of the known powder in each of three wells of a ceramic spot plate. A drop or two of each test reagent (or in the case of Tests 2 and 3, a drop of Solution A followed by a drop of Solution B) were used in each spot well containing the powdered known. Students rewrded their observations, and used their findings to identify an unknown provided by the instructor. Students also ran thin-laver chromatoerauhv usine a 9:l chloroform:methanol (by "volume) development sistem with commercial elass dates orecoated with silica eel (Analtech Uniplate Gecoited 2.6 x 20 cm prescored chromatography plates). Students prepared the sample for spotting by dissolving it in a few drops of a 5050 chloroform to methanol mixture. The plates were developed for about 20 min inglass tanks containing about 100 mLofthe developing solution.
-..
Table 2. Known Substances Provided to Students
Test Reagent 1. Marquisa
Reacts with Aspirin
To Yield a Red Color
Sodium Bicarbonate Foam 2. Cobalt Thiocyanatel
Stannous chlorideb
Methocarbamol
Purple Color
Quinine HCI
Light Blue
Yellow Color 'Marquis Reagent: 10 d m p 40% formaldehyde in 10 mLconc. sulfuricacid. Cobalt thiocyanatelstannouschloride: Solution A. 2% aqueous cobalt thiocyanate solution: Solution 0.5 g stannous chloride in 10 rnLcanc. hydrachlotic acid to 100 mL with water. 'p-DMAB: Solution A. 4Y-p-dimethylaminobenzaldehydeinethanol;Solution 0. conc. hydmchloric acid. 3. ~ D M A B ~
Meprobamate
The plates were visualized using both short and long wave W radiation (254nm and 366 nm) in a light box. Students determined the number of organic components possibly present in their "Exhibit" by the results observed from the development of the TLC plate, and any obsewation of solubility when preparing the unknown for spotting on the plates. Various mixtures of pbenacetin, quinine, sucrose, and salt were used in this portion of the experiment. Observant students arrived at the conclusion that not all organic molecules dissolve in the same solvents (for example, sucrose is insoluble in the chloroform/methanol solvent mixture). This conceut was utilized further in Exueriment 3 below. Students were surprised to learn how small an amount of substance was needed to run these tests, and they were even more surprised to learn that the amount provided (approx. 0.1 g in each vial) was quite a bit more than that usually found in most forensic samples. Alternatives
The solvents used in the TLC systems have been developed and tested for years for just this type of forensic separation, and no substitutes have been developed to the authors' knowledge. Student contact is limited by using covered glass tanks in a hood, and having the instructor place the plates in the tanks using tongs, and then replacing the cover. The color tests can be performed using aspirin, sodium bicarbonate, and quinine hydrochloride as written above. Acetaminophen fkom a ground-up commercial tablet can be substituted for the drug meprobamate, and the pDMAB test reagent replaced by ferric chloride: A5% aqueous solution gives a blue color with acetaminophen, a purple color with aspirin, and a bright yellow with quinine hydrochloride (you get three similar yellows from reacting the ferric chloride solution with hydrochloric acid). Experiment 3. Isolation and Identification
Experiment 3 was conducted in small groups a t the crime lab. The remainder of the class was given a problem set that required them to use wlor test data to determine possible components in a mixture and develop separation methods utilizing solubility information At the laboratory, each student group performed a "dry extraction" (water was not used) using a filter funnel and beaker. An unknown sample (in some cases an unmarked tablet, in others approx. 0.1 g of a powder mixture) was placed in the folded filter paper, and about 10 mL of a mixture of 50:50 chloroform to methanol mixture was poured slowly through to remove the "drugn component, while leaving behind diluents. (Note that absolute methanol was used, because salt or sucrose also would be extracted by an Volume 70 Number 4 April 1993
313
excessively "wet" solvent, along with the "drug" component). Students were given a choice of unknowns, including ground aspirin tablets, unmarked vitamin C tablets, and mixtures of benzocaine or caffeine with an inert component such as salt or sucrose. After extraction, the organic solvent was removed in the hood using a heat gun, and the students were shown how to make an infrared pellet using potassium bromide and their isolated drug component in a simple hand-held press. Students then obtained the infrared spectrum of their component using a Fourier-transform infrared spedrometer at the crime laboratory. Students were required to compare their sample spectra with the infrared spectra of several classes of drugs commonly encountered in criminal investigation. These spectra and a basic guide to infrared spectoscopy were provided to students prior to this class. Alternatives
Conclusion: A Cooperative Program Can Be Exciting
The purpose when beginning this project was to spark interest in the student for the "real world" of chemistry outside the classroom. The purpose of this article is not only to explain what was done and how it can be used in another classroom situation. but also to excite teachers into explormg cooperative education with any facilities ncarbv. Aside from the hundreds of forensic laboratories in the continental United States, there are community mlleges. universities. state. and local testine laboratories. a& numerous ind;strialfirms willing, perhaps, to invest in their future. Reagent chemicals, glassware and instruments not routinely available in a high school classroom (such as the Fourier Transform infrared spectrometer used in Experiment 3) are a routine part of a chemist's working tools, and a cooperative program can take advantage of this to benefit the students. Acknowledgment
Commercial acetaminophen, aspirin, and vitamin C tablets can be extracted with 99% isopropyl alcohol (rubbing alcohol) using the procedure above and yield excellent infrared spectra. The extraction also can be performed using 95q ethvl alcohol. The water oresent in the ethvl alcohol will mace it more time cons&ning to dry the simple for infrared soectroscoov. however. Althoueh these solvents are less hazardous &n chloroform, students still must be cautioned as to their flammable and toxic natures. Reference infrared spectra for these substances are found easily in the chemical literature.
The authors would like to thank Lowell Jacobson, Principal of Zama American High School, for permission to develop this program, and to Walter J. Stall, Chief Chemist, USACIL-Pacific, for his advice during its planning. We would especially like to thank LTC Larry N. Barker, the Commander of USACILPacific, for his enthusiastic support throughout all of this project. The opinions expressed in this manuscript are those of the authors and do not necessarily reflect the official opinion of Zama American High School, the Department of the Army, or the Department of Defense.
Final Lecture Program
Literature Cited
A brief follow-up lecture was presented to cover the points raised by these experiments, and to reinforce the idea of chemistry as an exercise involving curiosity about nature, gathering information and forming concepts to satisfy that curiosity, and then utilizing the information and conceots in a oractical manner to solve oroblems of interest. ky raised by the final priblem set were discussed at this time also.
1. Barnhalt. Edward R. Physiciam' Dosk f i f e r p m , 44th ed.; Medical Emnomies Campany: OradeU. NJ, 1990. 2. Clarke, E. G.C.. Ed.lsolofion andI&nfif~oflonofDlugs;ThePhmacevtiealRcaa: Inndon, 1978. 3. Budavalt, Susan, Ed. The Mamk In&, 11th ed.; Mexk & Co.: Rahway, NJ, 1989. 4. Hmver, John E., Ed. Romingron'aPhclrmunutimlS c i e m , 15th ed.; MsckPubhhing Co.: Easton, PA, 1975. 5.MiUs. Terry; Price. PstrieiaT.; Roberjon,J. Conrad.InstrvmentolDoto f o r D n r g h 1 ysis;Elsevier:NewYmL. NY, 1982. 6. Cade ofFederal Regulations, 21 CFR Part 1308, Schedule. of ConbolledSubdanbdanea. mfa of the Federal Resster. 1986.
314
Journal of Chemical Education
