Determination of total alkaloids in Croton tiglium by acid dye colorimetry

Objective To establish a method for the assay of the total alkaloids in Croton tiglium,and investigate the contents from different origins.Methods Acidic dye colorimetry was used for the determination of total alkaloids in Croton tiglium with magnoflorine as reference substance.Results Acid dye colorimetric conditions were as follows: pH6.0 buffer to 8.0 mL,adding 3.5 mL bromothymol blue,extracting with 8 mL chloroform,shaking out for 3 minutes,stewing for at least 40 min,then determining at the wavelength of 420 nm.The concentration of magnoflorine showed good linearity within the range of 0.024 6-0.147 3 mg,r=0.999 5,and the average recovery ratio was 99.0% with RSD of 2.75%.Conclusion This method is simple,highly sensitive,accurate and reproducible,which can be used for determination of the total alkaloids in Croton tiglium.