Date of Award

Summer 8-2-2019

Document Type


Degree Name

Master of Science (MS)


Forensic Science



First Advisor

Marta Concheiro-Guisan

Second Reader

Shu-Yuan Cheng

Third Advisor

Daniel Torres-Rangel


Fast and easy screening procedures are essential in any forensic toxicology laboratory to differentiate negative samples from presumptive positive cases. Immunoassay techniques, such as enzyme multiplied immunoassay technique (EMIT), are routinely employed as screening procedures. However, these techniques lack specificity (only differentiate group of drugs and not individual compounds) and it is difficult to add new compounds to the panel. Direct analysis of dried urine spots (DUS) by mass spectrometry (MS) offers a novel strategy to overcome these issues. DUS offer an improved storage alternative for biological samples, reducing costs and space requirements. In this work, an original method to screen for 15 common drugs of abuse in dried urine spots is described. The drug groups included opioids, prescription opioids, amphetamines and cocaine. Using a thin-layer chromatography-mass spectrometry (TLC- MS) interface, DUS samples were directly sampled and mass spectral data were analyzed. The method allows for analysis of DUS samples in less than five minutes and only 20 μL of sample is required for analysis. The method was validated according to SWGTOX guidelines, including limit of detection (LOD) and interference studies. The LOD ranged from 100 to 1,000 ng/mL, depending on the compound. The performance of the DUS screening method was compared to EMIT. The DUS method was more specific than the immunoassay screening but less sensitive than EMIT for certain analytes including morphine, hydrocodone, codeine, and 6-monoacetylmorphine. While this DUS screening method is rapid and easy to perform, urinary matrix components can possibly interfere with analytes and complicate results.



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