Criminalistics Laboratory - Toxicology Section

Toxicology

“Samples submitted to the DCI Laboratory Toxicology section will be tested in accordance with the current workflow and testing capabilities of the Toxicology Section. Routine analysis of blood samples typically includes both alcohol and drug analysis. Routine analysis of urine samples includes drug analysis and alcohol analysis by request.”

Lab Toxicology Section

Toxicology is the fundamental science of poisons. A poison is generally considered to be any substance which can cause severe injury or death as a result of a physicochemical interaction with living tissue. However, all substances are potential poisons since all of them can cause injury or death following excessive exposure.

The name forensic toxicology implies that the science has a legal purpose as its basis. Forensic Toxicology is defined by the American Board of Forensic Toxicology as the study and application of toxicology to the purpose of the law.

 

Instrumentation:

RANDOX
RANDOX screening instrument at the lab
Randox is a screening instrument that allows for comprehensive and sensitive screening for multiple compounds in a single assay.
Randox employs bio-chip technology which works based on ELISA principles (competitive antibody-antigen binding).  If drugs are present they will compete with labeled antigens for a limited number of antibody sites.  A Chemiluminescent reaction is then used to produce a measurable signal determining if certain drugs/drug classes are present.  Randox provides a preliminary screening result, positive results will be followed up with a more specific confirmation test. 
GAS CHROMATOGRAPH
Gas Chromatograph instrument

The Gas Chromatograph is an instrument that uses the principles associated with distillations and compound polarities to separate components in a sample mixture.  Components separate by adhering to the stationary phase at different locations on the column with the aid of the gas mobile phase.  Components are then eluted out of the column at different times, and detected by flame ionization.  This instrument is used mostly for determination of alcohol concentrations in blood and urine.

GAS CHROMATOGRAPH-MASS SPECTROMETRY
Gas Chromatograph-Mass Spectrometry instrument at the lab

Gas Chromatograph-Mass Spectrometry is the most used instrument of confirmation in the toxicology lab.  This instrument couples the abilities of a gas chromatograph with the mass spectrum of compounds to provide identification of compounds in a sample.  Most compounds can be detected using this instrument, but it might be necessary for an extra derivatization step to make sure the compound is volatile in the gas chromatograph.

LIQUID CHROMATOGRAPH TANDEM MASS SPECTROMETER
Liquid Chromatograph Tandem Mass Spectrometer at the lab

The Liquid Chromatograph Tandem Mass Spectrometer (LC/MS/MS) operates in a similar manner to the GC/MS with a few exceptions. Instead of using a gas mobile phase, the chromatograph uses a liquid mobil phase and the tandem mass spectrometers provide a greater sensitivity to trace amounts of compound. Like GS-MS, the LC/MS/MS is used to confirm the presence of the drugs that were found in the initial screening process. The liquid chromatograph tandem mass spectrometer has the advantage of the ability to look at a wider range of organic compounds in a sample, does not need the extra derivatization step and generally has improved sensitivity over a GC-MS.

 

 Frequently Asked Questions:

How many toxicology reports will I receive?

You will receive at least one report for the alcohol & screening results. Depending on the number of positive screens, there will be additional reports from different criminalists within the toxicology section.

How will I know when I have received the last report?

The last toxicology report will have a 90 day destroy statement on it. You can keep track for the total number of all reports for your case by the number in the upper right hand corner.

Is it possible to have additional testing done on a case?

Yes, additional testing is possible as long as there is sufficient quantity of sample, the DCI tests for the drug of interest, the DCI still has the evidence, and it hasn't been destroyed.

What do I do if I do not want the evidence destroyed?

Contact the DCI evidence room, in writing with the DCI case number, suspect or victim name, request that the sample be saved, the duration the sample needs to be saved and contact information.

Will DCI send the evidence to another laboratory?

1.    ISP cases only:  Yes, DCI will maintain the chain of custody and send the sample to another lab for testing.  You must indicate this in writing where you want the sample to be sent and the address.  The analysis is not a DCI expense.  Contact the DCI evidence room to make arrangements.  DCI Laboratory (515) 725-1500.

2.    Non-ISP cases: No.  We will return the evidence to your agency, upon written request, for your agency to send to a private lab.

How long does it take to get a screen or confirmation(s) analysis?

This depends on the number of cases and current backlog. For a specific question on a case, it's best to call the lab to discuss time frame for the completion of your evidence.

What is a metabolite of a drug and why would it be listed on a report?

Metabolites are formed as part of the natural biochemical process of degrading and eliminating the compounds from the body. Some drugs pass through the body intact while others may be partially or totally metabolized to another form to facilitate elimination. Thus a confirmation report may indicate the parent drug was identified, or it may indicate that a metabolite of the parent drug was identified or it may indicate that both were identified.