Examination of the relationship between paeoniflorin concentration and sulphur dioxide residues in the prepare slices of Paeonia Radix

OBJECTIVE To study the relationship between paeoniflorin concentration and sulphur dioxide residues in the prepare slices of Paeonia Radix randomly selected from the market.METHODS Ten samples of prepared slices of Paeonia Radix were purchased randomly from the market.Paeoniflorin in each sample was extracted via ultrasonic extraction with dilute ethanol.The Paeoniflorin concentration was then measured using HPLC.Acceptability was also examined.Sulphur dioxide residues in each sample was determined using iodometric titration.RESULTS Paeoniflorin concentration was 0.53-212μg·mL-1(r=0.9991,n=6) with good linearity.The average recovery rate was 99.01%,RSD 1.12%.According to the guidelines for Paeonia Radix in Pharmacopoeia of People′s Republic of China,only 3 of 10 randomly selected samples were qualified.We also found there was a negative correlation between paeoniflorin concentration and sulphur dioxide residues in the selected samples.CONCLUSION Sulphur dioxide residues has a negative influence on paeoniflorin concentration in Paeonia Radix.Paeoniflorin concentration is dramatically decreased in sulfur-processed Paeonia radix slices.