Study of Blending Method for the Extracts of Herbal Plants

The irregularity in herbal plant composition is influenced by multiple factors. As for quality control of traditional Chinese medicine, the most critical challenge is to ensure the dosage content uniformity. This content uniformity can be improved by blending different batches of the extracts of herbal plants. Nonlinear least-squares regression was used to calculate the blending coefficient, which means, there was no great absolute differences allowed for all ingredients. For traditional Chinese medicines, even smaller relative differences could be very important for all the ingredients. The auto-scaling pretreatment was used prior to the calculation of the blending coefficients. The pretreatment changed the distribution characteristics of same ingredients in different batches, so an improved auto-scaling pretreatment method was proposed. With the improved auto-scaling pretreatment, the relative differences decreased after blending different batches of extracts of herbal plants, according to the reference sample. Also, the content uniformity control of the specific ingredients could be achieved by the error control coefficient. In the studies for the extracts of Fructus gardeniae, the relative differences of all the ingredients were less than 3% after blending different batches of the extracts. The results showed that nonlinear least-squares regression could be used to calculate the blending coefficient of herbal plant extracts.