Abstract: This study describes an effective and convenient method for the separation and determination of the glucocorticoids residues in hair. Compared to most reported methods of high performance liquid chromatography using gradient elution，this analysis is performed utilizing isocratic elution reversd-phase pressurized capillary electrochromatography with UV detection. Eight glucocorticoids (betamethasone, dexamethasone, prednisone, prednisolone, prednisolone acetate, hydrocortisone acetate, cortisone acetate and corticosterone) are separated within 20min on a reversed-phase C18 column, with the Tris buffer (pH 8, 1.5 mM)– acetonitrile (65:35, v/v) as mobile phase and 245nm as the UV detection wavelength, and the flow rate of pump is 0.05 mL/min. All the compounds show good linearity in the concentration range of analysis. Detection limits (LODs) for all glucocorticoids are of 10-6 mol/L levels. The proposed method is applied to the analysis of hair samples. The interference of hair matrices were effectively eliminated by enzymatic digestion followed by a methanol extraction and a solid phase extraction (SPE) clean up step. Average recoveries of 71–85% at different fortified levels of glucocorticoids are achieved. This non-invasive method is useful for rapidly estimating the level of drug exposure in drug abuse and monitoring the compliance of therapeutic drugs.

Key words: glucocorticoids, hair testing, pressurized capillary electrochromatography, UV detection