Colorimetric method for the quantitative determination of acetaminophen in serum

Area of Science:

• Clinical Chemistry
• Analytical Toxicology

Background:

• Accurate quantification of acetaminophen in serum is crucial for managing therapeutic and toxic exposures.
• Existing methods may lack the sensitivity or specificity required for comprehensive clinical monitoring.

Purpose of the Study:

• To develop and validate a novel colorimetric assay for the quantitative determination of acetaminophen in human serum.
• To establish the sensitivity, accuracy, and potential interferences of the new method.

Main Methods:

• Preparation of a protein-free serum filtrate using trichloroacetic acid.
• Hydrolysis of acetaminophen to p-aminophenol.
• Colorimetric reaction with phenol and ammonium hydroxide to form an indophenol blue chromogen, measured at 620 nm.

Main Results:

• The method follows Beer's Law for acetaminophen concentrations above 50 mg/L.
• Excellent recovery (approximately 100%) compared to standards.
• High sensitivity, detecting concentrations as low as 1 mg/L.
• No interference observed from 70 tested drugs.
• Day-to-day coefficient of variation of 4%.

Conclusions:

• The developed colorimetric method offers a sensitive and reliable means for quantifying serum acetaminophen.
• This assay is suitable for monitoring both therapeutic and toxic levels of acetaminophen.
• The method's robustness and lack of interference make it a valuable tool in clinical toxicology.