Gas-chromatographic method for acetaminophen (N-acetyl-p-aminophenol) based on sequential alkylation

Area of Science:

• Analytical Chemistry
• Pharmacology

Background:

• Accurate quantification of acetaminophen is crucial for therapeutic drug monitoring and pharmacokinetic studies.
• Existing colorimetric and spectrophotometric methods may lack the sensitivity required for certain applications.

Purpose of the Study:

• To develop and validate a sensitive gas-chromatographic (GC) method for acetaminophen determination in serum.
• To evaluate the precision and applicability of the developed GC method for pharmacokinetic investigations.

Main Methods:

• Acetaminophen was derivatized to its O-heptyl-N-methyl derivative via sequential off-column and on-column alkylation.
• An internal standard, N-propionyl-p-aminophenol, underwent the same derivatization process.
• The derivative was analyzed using gas chromatography.

Main Results:

• The GC method demonstrated good correlation with established colorimetric and spectrophotometric assays.
• High within-run precision (CV=2.0%) and between-run precision (CV=4.0%) were achieved.
• The method proved to be more sensitive than conventional techniques.

Conclusions:

• The developed gas-chromatographic procedure provides a sensitive and precise method for acetaminophen quantification.
• This technique is well-suited for pharmacokinetic studies requiring accurate drug level measurements.
• The sequential alkylation derivatization offers a robust approach for acetaminophen analysis.