HPLC-MS/MS method for monitoring digoxin in children with small volume of plasma
Objective To establish a high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS)method for therapeutic drug monitoring(TDM)of digoxin in children.Methods The plasma samples 10 μL were precipitated protein by acetonitrile.Then,the analytes were gradient eluted on a Phenomenex Kinetex EVO C18 column(30.0 mm × 2.1 mm,2.6 μm)by HPLC-MS/MS with mobile phase consisted of water(0.05%formic acid and 2 mmol·L-1 ammonium acetate)-methanol at the flow rate of 0.55 mL·min-1.The mass detection was performed in positive ionization mode using the electrospray ionization(ESI)source.Dynamic multiple reaction monitoring mode(dMRM)was used to quantify at m/z 798.6→651.5(digoxin)and m/z 801.6→654.5(digoxin-d3),respectively.The selectivity,standard curve,precision and extraction recoveries,matrix effect,and stability were investigated.Results The retention time of both digoxin and internal standard was 1.39 min.The linear range of digoxin in human plasma was among 0.25-8.00 ng·mL-1,a typical standard curve was y=18.08 × 10-2x+29.71 × 10-4(r2=0.995 77).The intra-day and inter-day accuracies of digoxin were less than 15%Extraction recovery rate was 91.00%-99.50%.Stability studies showed good results.Matrix factor normalized by internal standard was within acceptance criteria.The measurement results were in line with the national requirement of External quality evaluation.This method was fully verified and applied to determine the plasma digoxin concentrations of 65 pediatric patients.Conclusion This LC-MS/MS method was simple,rapid and accurate.It is approved appropriate and practical for the therapeutic drug monitoring of digoxin in routine clinical laboratory practice,especially for children.
digoxinhigh performance liquid chromatography-tandem mass spectrometry methodchildrentherapeutic drug monitoringprotein precipitation