Novel Spectrophotometric Method for the Quantitation of Urinary Xanthurenic Acid and Its Application in Identifying Individuals with Hyperhomocysteinemia Associated with Vitamin B₆ Deficiency

Figure 1

Spectral scan for xanthurenic acid after reacting with Fe³⁺-TPTZ complex in acidic buffer (pH = 3.6) exhibiting a maximum absorption peak at 593 nm. The absorption peak represents the formation of Fe²⁺-TPTZ (intense blue color). A = 8 μg XA in 0.1 mL MeOH versus reagent blank, B = 4 μg XA in 0.1 mL MeOH versus reagent blank, and C = reagent blank versus H₂O.