Iowa Department of Public Safety Division of Criminal Investigation

DNA Casework Section

Latent Prints & Impression Identification


Questioned Documents


Trace Evidence


DPS Main Page

Iowa Death Investigator's Association

Search WWW Search DPS Website



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 labelled 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. 



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


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.

Gas Chromatograph


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.

Liquid Chromatograph

Click here to sign up for email notifications