Optimizing sample preparation workflow for bioanalysis of oligonucleotides through liquid chromatography tandem mass spectrometry

•Phenol:dichloromethane (2:1, v:v) surpassed other conventional extraction methods.•Ethanol precipitation (−80 °C, 5 min) was the optimal drying conditions.•The developed workflow provided a quantitative range of 0.25–1000 nM.•MS parameters were optimized through the central composite design.