An improved spectrophotometric method for the determination of free, bound and total N-acetylneuraminic acid in biological fluids

The spectrophotometric periodate-resorcinol method for the measurement of free, bound and total N-acetylneuraminic acid has been modified. The proposed method improves sensitivity by 27%, reduces the time of analysis by 33–52% and addresses interferences from biological substances. The improved procedure was applied to serum and urine samples for the determination of free, bound and total N-acetylneuraminic acid and compared successfully to the method reported by Jourdian et al. and to a commercially available enzymatic method. The results show that the proposed method is reliable, simple and convenient for routine use in clinical laboratory.