Here is a procedure for isoquinoline alkaloids Chromatographic system: HPLC with UV detector at 304 nm Column: 25 cm x 4.6 mm L1, 3-10 µm Flow rate: 1.5 mL/min Solution A: 99.8 mL of water with 0.2 mL of diethylamine adjusted to pH 3 with formic acid Solution B: 99.8 mL of acetonitrile with 0.2 mL of diethylamine Mobile phase: Solution A and Solution B (84:16) Standard solution: boldine 0.012 mg/mL in mobile phase Sample solution: Weigh 1 g of powdered Boldo. Add 50 mL of hydrochloric acid, mix and heat in a water bath at 80° for 30 min. Filter and take the residue with 50 mL of hydrochloric acid, mix and heat in a water bath at 80° for 30 min. Filter and repeat the procedure. Combine the filtrates and extract with a mixture of ethyl acetate and hexane (1:1). Bring the aqueous phase to pH 9.5 with diluted ammonia. Extract successively with 100, 50 and 50 mL of methylene chloride. Combine the organic phases and evaporate to reduced pressure. Dissolve the residue with mobile phase and transfer to a 10-mL volumetric flask. Complete to volume with mobile phase and mix. System suitability: Relative retention times are 0.9 for isoboldine, (1.0 for boldine), 1.8 for isocorydine N-oxide, 2.2 for laurotetanine, 2.8 for isocorudine, 3.2 for N-methylaurtetanine. The relative standard deviation is NMT 2.0%. Procedure: Inject 20 µL. Calculate the percentage of alkaloids using the sum of peak responses of all peaks identified.