A Sensitive Rapid and Environmentally Friendly UHPLC Assay Method for the Determination of Thymoquinone in Plasma...

A precise, swift and environmental-friendly reverse phase ultra-high performance liquid chromatographic assay for the determination of thymoquinone (TQ) in plasma samples using thymol (TM) as an internal standard was developed and validated. The method used a high strength silica C18 1.7 μm column (100 × 2.1 mm) with an isocratic mobile phase consisting of a blend of methanol and 20 mM potassium dihydrogen ortho-phosphate (90:10 v/v; pH of 4.2). The selected eluent provided a short run time (≤2 min), better peak symmetry, lower limit of quantification of 10 ng/mL and satisfactory values of other chromatographic parameters including resolution (Rs = 1), capacity factor (k = 21.5 and 14.5 for TQ and TM, respectively), selectivity (α = 1.482) and number of theoretical plates (N = 1653 and 784 for TQ and TM, respectively). The method was efficiently applied to a pharmacokinetic study of TQ following an intraperitoneal administration of 2 mg/kg in mice. The concentrations of TQ in plasma were measurable up to 12 h with Cmax of 404.08 ± 28.91 ng/mL, T1/2 of 2.31 ± 0.10 h and area under plasma concentration-time curve of 1527.00 ± 46.61 ng/mL × h.