SFC-MS for the identification and estimation of ethambutol in its dosage form and in human urine samples

Abstract

An ecofriendly, specific, accurate and precise SFC-MS method (using TurboIonSpray probes) is described for the determination of ethambutol in its pharmaceutical dosage form as well as in human urine samples by using supercritical carbon dioxide (SC-CO₂, 90%) as the mobile phase at a flow rate of 2 mL min⁻¹ and methanol : formic acid (100 : 0.1 v/v, 10%) as a modifier at a flow rate of 0.2 mL min⁻¹. Supercritical carbon dioxide (SC-CO₂) is an environmentally friendly mobile phase which has outstanding penetration power, negligible toxicity and low viscosity. EMB was determined in less than 5 min using a C18 reverse-phase fused-core column (Inertsil ODS-C18, 100 mm × 4.6 mm, 5 μm). The method was validated according to the International Conference on Harmonization (ICH) and US-FDA guidelines with values of selectivity, specificity, linearity, extraction recovery, matrix effect, accuracy and precision in the working range of 0.1 to 20 μg mL⁻¹ with an accuracy (% RE) of EMB of −6.00 to 6.00%. The proposed method was successfully applied to human urine samples and marketed formulations from various manufacturers.