Comparison of oxycodone in vitreous humor and blood using EMIT screening and gas chromatographic-mass spectrometric...

Vitreous humor may serve as a useful alternative specimen for oxycodone analysis in death investigations where blood samples are not available or are of poor quality or limited quantity. The purpose of this study was to investigate the relationship between immunoassay results and gas chromatography-mass spectrometry (GC-MS) quantitation of oxycodone in postmortem vitreous humor and blood. When used with vitreous humor calibrators, the Microgenics DRI Oxycodone (EMIT) Assay was found to be linear from 25 to 500 ng/mL with an limit of detection of 25 ng/mL. Vitreous humor and postmortem blood precipitate immunoassay responses in 57 oxycodone-positive cases were found to be correlated (r(2) = 0.69, p < 0.01). Confirmation and quantitation of oxycodone in vitreous humor by GC-MS was linear from 50 to 1000 ng/mL with a limit of detection of 10 ng/mL and a limit of quantitation of 50 ng/mL. In 30 cases, oxycodone vitreous humor concentrations ranged from less than 50 to 945 ng/mL, and blood concentrations ranged from 103 to 768 ng/mL. The average vitreous humor/blood ratio was 1.16 and ranged from 0.12 to 3.26. Disparities between vitreous fluid and blood oxycodone concentrations were seen in a few cases.