Direct determination of benzodiazepines in biological fluids by restricted-access solid-phase microextraction

Area of Science:

• Analytical Chemistry
• Biomedical Engineering
• Forensic Science

Background:

• Solid-phase microextraction (SPME) is a common technique for analyzing biological samples.
• Direct SPME sampling of biological matrixes presents challenges, including protein interference.
• Benzodiazepine detection in biological fluids is crucial for clinical and forensic toxicology.

Purpose of the Study:

• To develop a biocompatible SPME fiber for simultaneous protein fractionation and benzodiazepine extraction from biological samples.
• To interface the developed SPME fiber with HPLC-UV for efficient compound separation and quantification.
• To validate the method's performance in terms of linearity, precision, and detection limits.

Main Methods:

• Preparation of a biocompatible SPME fiber coated with alkyl-diol-silica (ADS) restricted-access material.
• Simultaneous protein fractionation and direct extraction of benzodiazepines from urine samples.
• Analysis using High-Performance Liquid Chromatography with Ultraviolet detection (HPLC-UV) and an isocratic mobile phase.

Main Results:

• The ADS-SPME fiber effectively fractionated proteins and extracted target benzodiazepines.
• Detection limits for clonazepam, oxazepam, temazepam, nordazepam, and diazepam were established.
• The method demonstrated excellent linearity (R2=0.9918) over a wide concentration range (500-50000 ng/mL).
• High precision was observed with a relative standard deviation (RSD) of approximately 6% for injection repeatability and intra-assay precision.

Conclusions:

• The developed ADS-SPME fiber offers a robust and simple approach for direct benzodiazepine determination in biological fluids.
• This method overcomes limitations of traditional SPME by simultaneously handling protein matrix effects.
• The technique shows promise for routine toxicological screening and therapeutic drug monitoring.