Detection of dopamine and catecholamine isoquinolines in cell samples by liquid chromatography-tandem mass spectrometry

A method of high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for determining Dopamine ( DA ) , Salsolinol (Sal) and N-methyl Salsolinol (NMSal) simultaneously in cells was established. After ultrasonic disrupted and centrifuged, the supernatant of cell sample was deproteined by 1 mol/L percholric acid solution (PCA). Then a 5μL of the supernatant of the sample was separated on a Discovery® HS F5 column (150mm × 2.1mm,3μm) with a mobile phase of the buffer ( 5mmol/L ammonium formate ( pH 3.0)methanol (80: 20, V/V) ) at a flow rate of 0.15mL/min. Both separation and detection were performed on the Agilent 1100 series HPLC system coupled with 6460 mass spectrometer operating in multiple-reaction monitoring (MRM) mode. 3 ,4-Dihydroxybenzylamine (DHBA) was used as the internal standard. The method showed a good linearities ( r > 0.9995 ) for the quantification of DA, Sal and NMSal in the concentration range of 0.5 -100μg/L. The limits of detection were 0.20,0.34,0. 33μg/L, respectively. The relative standard deviations of the intra-day and inter-day were both less than 8%. And the recoveries of DA, Sal and NMSal were 91.4%-109.6% ,87.4% - 109.7% , 88.0%-102.7% ,respectively. The result indicated that the concentration of DA,Sal increased in the cells treated with 300u,mol/L H₂O₂. The method is simple, high sensitive and selective, and suitable for DA1SaI and NMSaI analysis in cells.