Improved fluorometric quantification of urinary xanthurenic acid

Area of Science:

• Clinical Chemistry
• Biochemical Analysis
• Analytical Chemistry

Background:

• Urinary xanthurenic acid (XA) measurement is crucial for diagnosing vitamin B6 deficiency disorders.
• Existing methods for urinary XA quantification are often complex and time-consuming.

Purpose of the Study:

• To develop a simplified, rapid, and reliable fluorometric method for measuring urinary XA.
• To improve upon current cumbersome techniques for clinical laboratory application.

Main Methods:

• Utilized a solid-phase extraction column with a trimethylaminopropyl group bound to silica for purification and concentration of XA.
• Quantified XA in the acidic eluate using a fluorometric approach.
• Validated the method's linearity, precision, and correlation with HPLC and spectrophotometric procedures.

Main Results:

• The method demonstrated linearity from 0.2 to 10.0 mg/L.
• High precision was observed with day-to-day coefficients of variation of 1.2% and 2.6%.
• Excellent correlation was found with established HPLC (r=0.99) and spectrophotometric (r=0.98) methods, with insignificant interference from common substances.

Conclusions:

• The developed fluorometric method offers a rapid, simple, and accurate means for quantifying urinary XA.
• This technique is well-suited for routine use in clinical laboratories for assessing vitamin B6 status.
• The method effectively purifies XA from urine, overcoming limitations of previous assays.