Leucomalachite green assay for free hemoglobin in serum

A new colorimetric assay for the determination of serum free hemoglobin utilizing the noncarcinogenic compound leucomalachite green is described. The reaction is complete in 8 min, with the resulting color stable for at least 30 min. The absorption maximum for the leucomalachite green reaction product was observed at 617 nm. Precision studies at 50 and 300 mg/l free hemoglobin concentrations resulted in within-run variations of 1.9 and 1.7%, while the day-to-day variations were 6.9 and 4.0%, respectively. Accuracy studies at concentrations of 50, 150 and 300 mg/l resulted in recoveries of 88, 95 and 98% of theoretical values.