[Detection of glucocorticoids by pressurized capillary electrochromatography with ultra-violet detection and its...

An effective and convenient method for glucocorticoid analysis in hair by reversed-phase pressurized capillary electrochromatography (pCEC) with ultra-violet (UV) detection was developed. Eight glucocorticoids (betamethasone, dexamethasone, prednisone, prednisolone, prednisolone acetate, hydrocortisone acetate, cortisone acetate and corticosterone) were separated within 20 min in an isocratic mode pCEC. The separations were performed on a reversed-phase C18 column, and with 245 nm as the UV detection wavelength. The mobile phase was composed of 1.5 mmol/L Tris buffer (pH 8.0) and acetonitrile (65: 35, v/v), at a pump flow rate of 0.105 mL/min. All of the compounds showed good linearity in the range of 0.036 - 4.0 mmol/L. The limits of detection (LODs) for all glucocorticoids were of microg/g levels. The proposed method was applied to the analysis of hair samples. The interference of hair matrices was effectively eliminated by protein enzymatic digestion, followed by a methanol extraction and a solid phase extraction (SPE) clean up step. The average recoveries of 71% - 85% at different fortified levels of glucocorticoids were achieved. This non-invasive method is useful for rapidly estimating the level of drug exposure in drug chronic abuse and monitoring the compliance of therapeutic drugs.