Determination of morphine and related alkaloids in crude morphine, poppy straw and opium preparations by micellar electrokinetic capillary chromatography

KcA rapid method for the determination of morphine and related alkaloids in crude morphine, poppy straw and opium preparations by micellar electrokinetic capillary chromatography (MEKC) has been developed. Morphine, codeine, thebaine, oripavine, papaverine, narcotine, narceine, cryptopine and salutaridine were separated in less than 10 min using a 70 cm x 50 μm I.D. uncoated fused-silica capillary column with a buffer consisting of 10% dimethylformamide, 90% 0.05 M cetyltrimethylammonium bromide, 0.01 M potassium dihydrogen orthophosphate, 0.01 M sodium tetraborate, pH 8.6. An applied voltage of -25 kV and a temperature of 28°C gave the best separation of the alkaloids. Pholcodine was used as the internal standard. The compounds were detected by UV at 254 nm. The levels of morphine and related alkaloids determined by MEKC were in good agreement with those determined by high-performance liquid chromatography (HPLC). The coefficients of variation for area calculation (%C.V.) for multiple sample and standard injections by MEKC were slightly greater than for HPLC but were still acceptable (morphine content of poppy straw: %C.V. MEKC 1.7%, %C.V. HPLC 0.3%).