Kinetic fluorimetric study of the oxidation reaction of folinic acid (leucovorin) with potassium permanganate. Determination in human urine

In this study a kinetic fluorimetric method for the determination of folinic acid (leucovorin, LV) in human urine has been developed. The fluorescence emission generated by the oxidation reaction between LV and potassium permanganate in alkaline medium has been monitored at 360 nm (excitation wavelength 290 nm). The effect of instrumental and experimental variables on the reaction was investigated and a 0.17 M sodium hydroxide, 3.3×10−5 M KMnO4 concentration and a temperature of 70 °C were selected for the reaction. The concentration range has been optimized between 10 and 700 ng ml−1 of LV. The correlation coefficient was 0.9989. The sensitivity of the proposed method is 9.5 ng ml−1 (expressed as limit of detection in accordance with the Clayton criterion). The determination time per sample is smaller than 200 s. The proposed kinetic fluorimetric method has been applied to the direct determination of this compound in human urine. Recovery values from urine samples, containing LV, range from 82 to 110% (mean 96%).