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Types of Toxicological Testing

There are several types of toxicological analyses conducted for different purposes. These include forensic toxicological analysis, workplace drug testing and clinical or hospital drug testing.

Forensic toxicological analysis is conducted by laboratories for medical-legal purposes, which include death and criminal investigations. The laboratory findings are intended for use in Court. Accordingly, all specimens are considered evidence and are received, maintained, processed and disposed under strict chain-of-custody practices. All analyses are conducted pursuant to scientifically acceptable and legally defensible standards, which include redundant procedures that incorporate both presumptive and confirmatory testing technologies.

While forensic toxicological analyses are not legally regulated, all work is subject to examination in Court. Laboratories are increasingly accredited by national or international organizations which set standards for laboratory practices. Standards and operations for forensic laboratory practices are the subject of a recent National Academy of Sciences report.

See http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=12589

Workplace drug testing is conducted by laboratories for administrative purposes, although results of such testing are often used as evidence in Court. Accordingly, all specimens are considered evidence and are received, maintained, processed and disposed under strict chain-of-custody practices. All analyses are conducted pursuant to scientifically acceptable and legally defensible standards, which include redundant procedures that incorporate both presumptive and confirmatory testing technologies.

What distinguishes forensic toxicological analyses from workplace drug testing is the limited scope of specimens and target analytes with the latter. This is based in the original intent for workplace drug testing, which is to identify drug ingestion among safety-sensitive federally-regulated transportation industries such as railroads, aviation, trucking and pipelines. Workplace drug testing is typically limited to urine and hair, although oral fluid and sweat are being evaluated for applicability. Workplace drug testing is also limited primarily to drugs-of-abuse or potential abuse.

Workplace drug testing laboratories are regulated by the US DOT pursuant to CFR 49 Part 40. See http://www.dot.gov/dapc/.

Use of positive workplace drug testing results may be appropriate for some evidentiary purposes but not others without qualification or explanation.

Diagnostic or hospital drug testing is conducted in laboratories to assist in medical treatment. These laboratories may reside within a hospital or a separate facility. Analyses are conducted a rapidly as possible, typically without instrumental methods and without confirmation that is the hallmark of a forensic examination. Testing is typically limited to urine.

This is not to say that diagnostic drug testing is inaccurate. It is sufficient for the intended purpose. The same presumptive analytical technology (immunoassay) is used (albeit non-instrumental) that is used by forensic toxicological and workplace testing laboratories. However, definitive confirmatory testing is not conducted and generic drug class results (e.g. opiates) rather than specific substances (e.g. morphine) are typically reported. Whereas such findings may be sufficient for healthcare professionals to avoid administering a potentially contraindicated medication, such findings are inadequate to scientifically or legally establish the presence of any particular substance. With successful treatment, the significance and accuracy of diagnostic drug test results become moot. Such cannot be said for evidentiary testing.

Diagnostic or hospital drug testing is regulated by the US HHS Centers for Disease Control and Prevention. See http://wwwn.cdc.gov.

Use of “positive” diagnostic or hospital drug testing results without qualification or explanation is inappropriate for evidentiary purposes.

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).

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.

For a complete scope listing, see 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.