Solid-phase extraction of 1,4-benzodiazepines from biological fluids

Area of Science:

• Analytical Chemistry
• Forensic Toxicology
• Pharmacology

Background:

• 1,4-benzodiazepines are widely prescribed, necessitating reliable analytical methods for their detection.
• Accurate quantification in biological matrices like urine and plasma is crucial for clinical and forensic applications.
• Solid-phase extraction (SPE) is a common sample preparation technique for drug analysis.

Purpose of the Study:

• To investigate and optimize solid-phase extraction (SPE) methods for seven 1,4-benzodiazepines.
• To evaluate different sorbent materials and elution solvents for efficient benzodiazepine recovery.
• To validate the SPE method for analyzing benzodiazepines in biological samples like urine and plasma.

Main Methods:

• Investigated SPE of seven 1,4-benzodiazepines (oxazepam, diazepam, temazepam, nordazepam, brotizolam, adinazolam, midazolam) using prazepam as internal standard.
• Utilized C18 Sep-Pak cartridges and C2, C8, C18, cyanopropyl, phenyl, and cyclohexyl Bond-Elut sorbents.
• Analyzed recovery from aqueous buffers and spiked urine and plasma samples, varying pH and elution solvent composition.

Main Results:

• C18 Sep-Pak cartridges with methanol-water mixtures were effective for initial recovery.
• The C2 cartridge yielded the cleanest urine extracts for oxazepam.
• Recoveries exceeding 90% were achieved for multiple 1,4-benzodiazepines from urine and plasma using the C2 cartridge, with no endogenous interference.

Conclusions:

• The C2 cartridge offers a highly efficient and clean SPE method for analyzing multiple 1,4-benzodiazepines in biological samples.
• Optimized SPE conditions ensure high recovery and minimize interference, suitable for routine toxicological screening.
• Further optimization considered factors like drug concentration, sample volume, and cartridge reusability.