Gas chromatography with surface ionization detection: a highly sensitive method for determining underivatized codeine...

Area of Science:

• Pharmacology
• Analytical Chemistry
• Forensic Toxicology

Background:

• Accurate quantification of codeine and dihydrocodeine is crucial for therapeutic drug monitoring and forensic analysis.
• Existing analytical methods may lack sufficient sensitivity or require complex sample preparation.

Purpose of the Study:

• To develop and validate a sensitive capillary gas chromatography method with surface ionization detection (GC-SID) for determining underivatized codeine and dihydrocodeine.
• To compare the performance of GC-SID with conventional nitrogen-phosphorus detection (GC-NPD).

Main Methods:

• Extraction of codeine and dihydrocodeine from human plasma and urine using Sep-Pak C18 cartridges.
• Quantification using capillary gas chromatography (GC) coupled with surface ionization detection (SID).
• Dimemorfan was employed as an internal standard for calibration.

Main Results:

• High recovery rates (> or = 90%) were achieved for both codeine and dihydrocodeine.
• The GC-SID method demonstrated excellent linearity over the tested concentration ranges.
• A low detection limit of approximately 100 pg on column (2.5 ng/ml sample) was established.
• GC-SID exhibited over tenfold greater sensitivity compared to GC-NPD with lower background noise.

Conclusions:

• Capillary gas chromatography with surface ionization detection (GC-SID) provides an accurate and highly sensitive method for quantifying codeine and dihydrocodeine in biological matrices.
• The developed GC-SID method surpasses GC-NPD in sensitivity, making it suitable for precise drug level determination.