Use of dynamically coated capillaries for the determination of heroin, basic impurities and adulterants with capillary electrophoresis

Rapid, precise, accurate, and reproducible methodology using capillary electrophoresis (CE) with dynamically coated capillaries for the analysis of heroin and its basic impurities and adulterants is presented. Highly selective determination of the above solutes is obtained by analyzing the same sample preparation by two CE methods. For the determination of heroin, its basic impurities and basic adulterants, dynamic coating of the capillary surface is accomplished using a commercially available reagent kit with an added cyclodextrin ((CD) polycation coating followed by polyanion coating with dimethyl-β-cyclodextrin or hydroxypropyl-β-cyclodextrin). The addition of a cyclodextrin to the run buffer significantly improves the separation of these solutes. Neutral, acidic, and weakly basic adulterants which migrate near or after t0 do not interfere with the more mobile basic solutes. The determination of neutral, acidic, and weakly basic adulterants in heroin is accomplished using a modification of the above commercially available reagent kit. After first coating with a polycation, a negative coating is obtained using a surfactant sodium dodecyl sulfate. Micellar electrokinetic chromatography (MEKC) with dynamically coated capillaries gives an excellent separation of the neutral, acidic, and weakly basic solutes, with considerably shorter run times compared to conventional MEKC. In addition for this system, most basic solutes in heroin have longer migration times than the uncharged and acidic compounds.