Comparison of carbazole method and phloroglucinol method for chondroitin sulfate determination

We compared the determination of the concentrations of hydrolyzed and colored chondroitin sulfate (CS) by carbazole method and phloroglucinol method. The results reveal that the CS concentration by carbazole method and phloroglucinol method showed good linear relationship withtheir absorbance values within the ranges of 0.01~0.05 mgmL-1 and 0.1~1.0 mgmL-1, respectively. After 6 parallel tests on the same sample, the relative standard deviations (RSD) by carbazole method and phloroglucinol method were 3.90% and 4.28%, respectively, both with high precision. The two methods were spiked with 3 levels; the recoveries of carbazole method and phloroglucinol method were 98.0%~102.5% and 83.2%~106.6%, respectively. Thus, both carbazole method and phloroglucinol method can determine CS concentration accurately.