Comparison of HPLC-UV, GC-FID, and GC-MS for the analysis of cocaine and benzoylecgonine from vitreous humor and brain tissue

The purpose of this study is to look at in vivo cocaine metabolism in vitreous humor and brain tissue of male Sprague-Dawley rats 4-6 months of age employing the use of three analytical methods. Samples were run on HPLC-UV, GC-FID, and GC-MS and calculations were done to determine if adequate levels of cocaine and benzoylecgonine were seen in vitreous humor and brain. This allowed for direct comparison of sensitivity and quantitative analysis from three analytical methods simultaneously.; Findings and conclusions. HPLC detected cocaine in vitreous humor and brain and benzoylecgonine in the brain. Either benzoylecgonine levels in vitreous humor fell below the level of detection (∼100ng/ml) or low enzymatic activity caused incomplete metabolism of cocaine. Incomplete metabolism of cocaine in the vitreous humor may warrant the use of vitreous humor as a compartment for establishing a rate of postmortem metabolism. Analysis on GC-FID showed several unresolved peaks and levels of cocaine and benzoylecgonine could not be determined. GC-MS detected cocaine and benzoylecgonine in the vitreous humor and brain. The level of detection for GC-MS was ∼25ng/ml, four times more sensitive than HPLC. (Abstract shortened by UMI.)...