Abstract
We describe the use of capillary zone electrophoresis (CZE) for the qualitative and quantitative determination of major alkaloids (i.e., thebaine, codeine, morphine, papavarine and narcotine) in gum opium involving the analysis of alkaloids without derivatization or purification. Three extractions with 2.5% w/v aqueous acetic acid quantitatively extracted major alkaloids. The separation was carried out by CZE using a 7:3 mixture of methanol and sodium acetate (100 mM, pH 3.1) at a potential of 15Β kV, with UV detection at 224Β nm. Spiking of pure reference alkaloid standards in the opium extract was used for peak identification. The influences of buffer composition, pH and voltage on the separation of alkaloids were studied. The detection limit of each alkaloid dissolved in methanol was found to be 850Β ng/mL (morphine), 450Β ng/mL (thebaine), 500Β ng/mL (codeine), 550Β ng/mL (papaverine), and 500Β ng/mL (narcotine) at an injection pressure of 300Β mbar (injection volume, 4Β nL) with a signalβtoβnoise ratioΒ of 3:1. The external standard method was used for the quantification of alkaloids. The calibration plot was based on linear regression analysis. The relative standard deviation (RSD) for peak area and migration time was in the range of 1.03β3.56% and 0.34β0.69%, respectively. Percentage compositions (g%) of opium alkaloids in five gum opium samples were found to be in the range of 14.45β15.95 (morphine), 2.0β3.45 (codeine), 1.32β2.73 (thebaine), 0.92β2.37 (papavarine), and 3.85β5.77 (narcotine). The method developed is suitable for the routine analysis of major gum opium alkaloids in samples of forensic importance.