Anne ImObersteg is an analytical chemist as well as a toxicologist. She is a court-qualified expert in the analysis of controlled substances in their original form (powders, pills, plant material, liquids etc.), and the evaluation of clandestine laboratory by-products. As a chemist, Ms. ImObersteg also has the expertise to determine the ability of drug production given the chemicals found at the clandestine laboratory site.





NARCOTICS/CONTROLLED SUBSTANCES

Technically, the term "narcotics" means a substance which induces sleep. However, law enforcement often uses the term to encompass the entire spectrum of abused drugs, including stimulants such as cocaine or methamphetamine. "Controlled substances" is a more general term, and hence more accurate to describe the analysis of the original solid form (vs. toxicological specimen) of the drug, in bindles, baggies and syringes.

When a laboratory receives a seized sample from law enforcement, it is analyzed by a chemist to identify the substance. Often, not all the collected substances are tested. Laboratories have their own criteria for determining which specimens to test. A laboratory may have a policy that if the packages/bindles in one case are all similar in size and visual appearance, the square root of the items seized is tested. For example, if 100 small bindles are received, 10 will be randomly selected and tested.

ANALYSIS

The methods for analysis of controlled substances/narcotics in the solid form vary from laboratory to laboratory. Ideally, the sample is screened via a color or crystal test, and the results confirmed with an analytical instrument such as a GC/MS or FTIR. Most common for local criminalistics laboratories, is the use of color and crystal tests, since the tests are quick and inexpensive.

COLOR AND CRYSTAL TESTS, IN GENERAL

Analysis should be performed in a manner which eliminates contamination. The reagents used for the tests should be evaluated regularly for effectiveness and lack of contamination. A quality control specimen should be tested with the case material, or, at minimum, on a daily basis.

COLOR TESTS

Most laboratories perform a variety of tests. Generally they can be grouped into “presumptive” and “confirmatory”. Presumptive tests are usually color tests. Color tests can be subjective, and open to interpretation by the analyst. For example, using roadside color test kits, the “blue” color formed by PCP may be mistaken for the slightly different blue color formed by cocaine. In a laboratory, however, the testing procedure generally is in the form of a color scheme, with more than one color test being performed, each successive color test often being more specific that the previous test.

EXAMPLE: THE ANALYSIS OF METHAMPHETAMINE:

Methamphetamine can be found relatively pure, or cut with a variety of agents such as talcum powder, ephedrine, and substances from the manufacturing process. The result is a drug specimen that may or may not interfere with a color, crystal or GC/MS test.

A small sample of the drug is placed in the well of a ceramic or plastic plate ("spot plate") and a color reagent is added. Typically, a whole set of color tests are performed, eliciting positive and/or negative results. For methamphetamine, the color scheme may be as follows:

Use of the Marquis reagent produces an orange color which turns to brown. Use of sodium nitroprusside produces a blue color for methamphetamine also mephentermine) and a pink color for amphetamine. The Chen's reagent is often used to determine if cutters such as ephedrine is probably present as well. Other reagents such as Mecke, Froede, Scott, Van Urks, are often used as well to rule out other substances: the absence of a color turn also give the analyst valuable information.

CRYSTAL TESTS

An instrumental analysis is the preferred confirmation method. However, some laboratories use two crystal tests as a confirmation of the suspected positive sample. One drawback of a crystal test is the subjectivity of evauation. If a crystal test is to be used as a confirmation, the laboratory should photograph the crytals seen to document the test result and to allow an independent review of the results. Recognizing crystal shapes is a learned skill; overgrown crystals can take on a different appearance than young crystals, and some crystals may be difficult to distinguish from others by an inexperienced microscopist.

Methamphetamine crystal tests are often performed using the hanging drop method. About 0.5 to 1 mg of case material is placed into a cavity slide. 1-2 drops of 6N NaOH s placed into the cavity on top of the sample, and a cover glass, holding one drop of reagent, is placed over the cavity. The sample becomes volatile with the base and “moves” to the drop hanging just above it. The slide is examined under the microscope at 100x. Crystalline structures should be compared with standards.

Use of the reagent platinic bromide produces daggers (d or l) or bushs (dl). Use of gold chloride/phosphoric acid creates "clothespins" for d-methamphetamine and overlapping rods for dl-methamphetamine

INSTRUMENTAL ANALYSIS, GC/MS ETC.

Instrumental analysis is the more common standard of confirmation in progressive laboratories. There are a variety of different instruments which can be used. An example is the Gas Chromatograph/Mass Spectrometer (GC/MS). The GC/MS identifies the chemical by evaluating the molecular structure of the chemical. The molecule is bombarded with electrons, shattering the molecule into predictable pieces, depending on the structure and weak bonds in the molecule. In controlled substances testing,laboratories often perform a "total scan" of the compound. This scan identifies the drug by looking at all the pieces generated by the electron bombardment and comparing the pattern produced to a known standard.

CLANDESTINE LABS

Clandestine laboratory evidence is often received by a forensic laboratory. The evidence may arrive in a liquid, a solid, or a liquid/solid mixture. These items are tested to 1)identify the substance, 2)identify the procedure that was used and 3)determine the possible yield of production.

There are many methods for manufacturing drugs, and procedures and methods used by the clandestine laboratory "chemist" are constantly changing. Some chemicals used in one method of production for a methamphetamine lab, for example might be:

ephedrine or pseudoephedrine
hydriodic acid
red phosphorus
iodine
hydrogen sulfide
sodium hydroxide/lye
freon

In this type of manufacturing process, evidence submitted to the forensic laboratory may take the form of:

bottles and jars with amber or clear liquid
filter paper with a red substance
jars or bottles with white crystals, or cloudy liquid
and miscellaneous glassware with residue

A thorough analysis of the submitted items of evidence will enable the forensic chemist to identify the method used. In addition, by considering the lab equipment seized and the amount of reagents and starting materials available, a past and future yield capability may be estimated.