UHPLC/ESI-Q-TOF-MS method for the measurement of dopamine in rodent striatal tissue: a comparative effects of intranasal administration of ropinirole solution over nanoemulsion.

An ultra high performance liquid chromatography-electrospray ionization-tandem mass spectrometric method (UHPLC/ESI-Q-TOF-MS) for the analysis of dopamine (DA) in Wistar rat brain homogenate has been developed and validated. The chromatographic separation was achieved on a Waters ACQUITY UPLC™ BEH C18 (100.0 mm × 2.1 mm; 1.7 µm) column using isocratic mobile phase, consisting of acetonitrile and Formic acid (0.1% w/v) (10: 90; v/v), at a flow rate of 0.15 ml min(-1) . The transitions occurred at m/z 154.04 → 137.006 for DA, and m/z 184.204 → 166.08 for the internal standard. The recovery of the analytes from Wistar rat brain homogenate was optimized using liquid-liquid extraction technique (LLE) in ethyl acetate. The total run time was 3.5 min and the elution of DA occurred at 1.44 ± 0.05 min. The linear dynamic range was established over the concentration range 75-750 ng mL(-1) (r(2) ; 0.9921 ± 0.0005) for DA. The intra-assay and inter-assay accuracy in terms of % CV was in the range 0.73-2.80. The lower limit of detection (LOD) and quantitation (LOQ) for DA was 0.278 and 0.844 ng mL(-1) , respectively. Analytes were stable under various conditions (in autosampler, during freeze-thaw, at room temperature, and under deep-freeze conditions). The developed method was successfully applied for in vivo profiling in rodents.