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THE EDUCATOR - Fall 2000

Dos and Don'ts of Sampling

By Frank Boshears, Forensic Chemist, Washington State Patrol Crime Lab

As more agencies process their own clandestine drug labs the Crime Laboratories are seeing more cases ubmitted where the samples have been seriously compromised. In some cases the samples were in such poor condition that they could not be analyzed. The samples are sometimes packaged incorrectly, or the containers are the wrong type for the samples, or instead of samples, an entire container is submitted. With that in mind, here are some guidelines for packaging and sampling.

Whenever possible, take samples. This may seem obvious, but we have been getting many submissions where the respond ing officers simply packaged up the containers as they were found. Do not send in quartjars of white powder or gallon cans of unknown liquids. If you have a large amount of powder, weigh it at the scene and submit a sample—a gram or so is plenty (the amount that can fit on the end of a tongue depres sor). In the case of liquids, a few milliliters (a tablespoon or so) is usually enough. In the case of tablet binder, a couple of ounces (again, a couple of tablespoons) is sufficient. The Crime Labs do not have the capabilities or desire to store large containers. Red phosphorous, in particular is dangerous to store and ship in large quantities.

Always try to take representative samples, particularly of liquids. Often, there will be a very thin top layer floating on a lower layer. Make sure to get both layers. If the lower layer is basic (pH greater than 7) the top layer would be the layer con taining any methamphetamine. On the other hand, if the lower layer is acidic, then the methamphetamine may be in the lower layer. In the case of pill extraction, the liquid would likely con tain the ephedrine (or pseudoephedrine), but the solid should be sampled as well, to be tested for binder material. If lithium strips are sampled (small samples) they must be put into a vial, along with some organic solvent (usually the cook will have them covered in a solvent).

The person doing the sampling should try and sample only those items necessary for the case. Remember that a lot of the things you find may have nothing to do with making drugs. On the other hand, make sure to take enough samples. While it is not necessary to sample every toluene or alcohol can containing a liquid, you should check to see if it is a clear, colorless liquid, and not a colored, cloudy or a bilayer liquid (two different liq uids, one floating on top of another). If there has been a fire or explosion, check to see if there is any residue of whatever caused the fire. For example, a pan containing a liquid on top of the stove. It may not have all burned up and it could contain fin ished product. Some things, like HC1 generators, do not need to be sampled; however, the end of the hose can sometimes yield methamphetamine. Do not sample ammonia tanks. Testing with pH paper and/or Drager tubes is sufficient. And, in no circum stances ever transport or submit any pressurized gas tank to the Crime Labs! Other items that should not be sampled include oils, such as cooking or motor, food products (a Coke bottle with a brown, fizzy liquid inside is probably cola), anything that has live insects or is moldy, and bodily fluids. On the other hand, a pop bottle containing a yellow solvent or a toilet containing a cloudy red liquid with a pH of 1 or 14 may be significant. Take nothing at face value. Everything must be evaluated.

The packaging of the samples is also important. ‘While plas tic zip-lock bags work for most dry powders, iodine must be put into glass vials with Teflon-lined caps. Iodine will seep through most plastics and contaminate everything in the sample can. Wet powders or pastes should be put into glass vials or small jars. All of the vials or jars used for samples should be glass, screw-top, with phenolic caps and Teflon cap liners. Avoid using snap-top, polypropylene, polyethylene or metal lids. The snap-top, polypropylene and polyethylene caps will not hold in solvents and the metal will not stand up to acids. Phenolic plas tic caps are hard and usually black or green. If you can scratch the cap with your fingernail or bend it, it is not phenolic. Most vials marketed for use for environmental samples do not have the right type of lids, even if they have a Teflon liner. These caps often leak, or swell up and fall off of the vials. An added precaution, while not always necessary, is to place each sample inside a plastic zip-lock bag, in case the vial leaks or breaks. Also place kitty-litter into the cans with the samples, to provide cushioning and also to soak up any liquids or odors that may leak.

If you ever have any questions about samples or would like a day-long class in sampling, please contact your nearest Crime Lab.