Vitreous fluid quantification of opiates, cocaine, and benzoylecgonine: comparison of calibration curves in both blood and vitreous matrices with corresponding concentrations in blood.

Vitreous fluid specimens are often used in the Montgomery County Coroner's Office as a second matrix confirmation for both cocaine and opiate analyses. In this manuscript, calibration curves constructed for both vitreous and blood were used to quantify vitreous specimens to evaluate if any matrix effects occur when measuring vitreous specimens using a calibration curve in blood. Cases that screened positive by ELISA for cocaine metabolite and opiates were confirmed by solid-phase extraction. Gas chromatography with mass spectral detection in the positive electron impact mode was used for the detection and quantification of oxycodone, free morphine, codeine, 6-monoacetylmorphine, hydrocodone, cocaine, and benzoylecgonine. For interpretive purposes, no significant matrix effects were found in concentrations of vitreous specimens quantified with a calibration curve constructed in a blood matrix. After determining that vitreous fluid can be accurately measured with blood calibrators, a comparison was made between blood and vitreous concentrations for the above analytes. Concentration differences between blood and vitreous specimens for each drug are evaluated with selected case histories included.