Forensic Toxicology


Scope of Toxicological Analysis

The Toxicology Discipline conducts both qualitative and quantitative analyses. Qualitative analyses are intended to identify particular substances in a specimen. Quantitative analyses are intended to both identify particular substances and to establish how much is present. Quantitative analyses are necessarily more complicated than are qualitative analyses because quantitative analyses must be calibrated and controlled for each particular substance. Because of this added complexity and for the sake of timeliness, the Toxicology Discipline may elect to report qualitative findings without quantification or it may limit analyses to specimens where quantitative findings may be reasonably interpreted. Quite often, the mere presence of a substance in a specimen is sufficient to answer the question whether it was consumed.

The Toxicology Discipline routinely conducts quantitative analyses for ethanol (alcohol) and related volatiles such as acetone, methanol and isopropanol. Headspace/gas chromatography (HS/GC) is employed for this purpose. This method may be applied to both liquid (blood, urine, etc.) and solid (homogenized liver, etc.) specimens and is specifically calibrated and controlled for these volatile substances. Non-biological specimens such as beverages may be analyzed as well.

The Toxicology Discipline routinely conducts qualitative analyses for both therapeutic and abused drugs. Some of the many drugs and drug classes detected with these analyses include the sympathomimetic amine class (amphetamine, methamphetamine, MDMA, ephedrine, pseudoephedrine, etc.), cocaine and metabolites, opiate class (morphine, codeine, hydrocodone, oxycodone, etc.), benzodiazepine class (diazepam, alprazolam, etc.), barbiturate class (phenobarbital, butalbital, etc.), cannabinoids (from marijuana), other analgesics (fentanyl, propoxyphene, meperidine, methadone, tramadol, etc.), antidepressants (amitryptyline, Prozac®, etc.), muscle relaxants and sedatives (Soma®, zolpidem, etc.).

The Toxicology Discipline also routinely conducts analyses for carbon monoxide (as carboxyhemoglobin). This list is not intended to be complete; rather it represents only a small sampling of the substances that comprise the scope of analysis. Please contact the laboratory for more specific information.

Because toxicological findings are used in Court, analyses are conducted according to strict practices and methods which are legally defensible. These practices and methods meet the standards established by the, American Society of Crime Lab Directors Laboratory Accreditation Board (ASCLD/LAB). All submitted specimens are maintained under chain-of-custody in a secure environment intended to preserve the material for the intended analyses.

Analyses are typically conducted in two phases. The presumptive phase is intended to provide indications whether a particular drug or drug class is present. Enzyme-linked immunosorbent assay (ELISA or EIA) is typically employed for this purpose. Specimens that appear to be presumptively positive for one or more drugs or drug classes are then subjected to the confirmation phase, which is intended to provide more definitive identification of the substances that may be present.

Confirmation analyses are typically conducted with methods that have greater specificity than do presumptive analyses and which may examine the chemical structure of each substance as a means of identifying them. Gas chromatography/mass spectrometry (GC/MS) and/or liquid chromatography-multiple reaction monitoring mass spectrometry (LC-MRM MS) are typically employed for this purpose. Some substances may not be detected with ELISA, so the presumptive phase may include a general screen employing GC/MS. In such a case, the confirmation phase may comprise a repeated analysis with another aliquot or another specimen collected from the same subject.

Positive findings are reported only when they are sufficiently confirmed.

See the appendix for our full scope of analysis.

DUI/D, traffic fatality, homicide, and some other case types typically get a limited scope of analyses. All cases are analyzed for ethanol and related volatiles. Scope of drug analysis is limited to the following:

Amphetamine class, barbiturate class, benzodiazepine class, cannabinoids, cocaine and/or metabolite(s), fentanyl, opiate class, methadone, carisoprodol/meprobamate, zolpidem, tricyclic antidepressants, dextromethorphan, tramadol.

Please contact the laboratory at (205) 982-9292 if you have questions regarding the scope of analysis for your case or require additional/specialized testing.