Sensitive assay for cocaine and benzoylecgonine using solid-phase extraction and gas chromatography

Area of Science:

• Analytical Chemistry
• Forensic Toxicology
• Pharmacology

Background:

• Cocaine and its primary metabolite, benzoylecgonine, are frequently abused substances.
• Accurate and sensitive quantification is essential for clinical monitoring and forensic investigations.
• Existing methods may require larger sample volumes or lack simultaneous detection capabilities.

Purpose of the Study:

• To develop and validate an improved method for the simultaneous determination of cocaine and benzoylecgonine.
• To enhance analytical sensitivity and precision for these compounds in biological matrices.
• To facilitate analysis using small sample volumes, such as plasma.

Main Methods:

• Gas chromatography with nitrogen-phosphorus detection (GC-NPD).
• Solid-phase extraction (SPE) for sample cleanup.
• Derivatization of benzoylecgonine to its butyl ester for GC analysis.
• Use of n-propyl ester of benzoylecgonine as an internal standard.
• Capillary column chromatography for separation.

Main Results:

• The method demonstrated linearity over a concentration range of 4 to 2000 ng/ml for both cocaine and benzoylecgonine.
• Good precision was achieved across the validated concentration range.
• The assay is suitable for analyzing small plasma volumes (250 microliters).

Conclusions:

• The described GC-NPD method provides a reliable and efficient means for simultaneous cocaine and benzoylecgonine quantification.
• Its applicability to small plasma volumes makes it particularly valuable for clinical and forensic toxicology.
• This improved assay enhances the ability to monitor drug use and exposure.