Quantitative Determination of Total Alkaloids in Piper Longum with Acid Dye Colorimetry

A method is established to quantitatively determine total alkaloids in Piper Longum by acid dye colorimetry. Piperine was used as a control standard and bromothymol blue as dye. The buffer solution of different pH value, the amount of buffer solution and the amount of acid dyes is investigated by acid dye colorimetry, the method for content determination of alkaloids of Piper longum is optimized. Optimum method of determination of alkaloids of Piper Longum is as following: the pH value of is 6.0, the amount of the buffer solution is 4.0mL, the volume of the acid dye is 6.0mL. It is simple, accurate and reliable, economic and fast.