Plasma NE Quantification by HPLC-ECD

High-performance liquid chromatography with electrochemical detection (Waters-2465, Waters Corporation, USA) was used for measuring plasma levels of NE as described previously34 (link). Briefly, samples or standards were derivatized with o-phtaldialdehyde; 20 μl of the resulting mixture was automatically loaded onto a Novapark C18 reverse-phase column (150 × 4.6 mm, 4 μm particle size, Waters), using a refrigerated autoinjector. The mobile phase consisted of NaH₂PO₄ (0.05 M, pH 6.8) with 20% methanol, and the flow rate was 1 ml/min delivered by a Waters pump. The NE concentration was detected and analyzed using Empower 3 analytical software (Waters).