two-dimensional liquid chromatography-tandem mass spectrometry tandem dual-column high-performance liquid chromatography atmospheric pressure chemical ionisation tandem mass spectrometry 2009-06-22T10:12:28Z CHMO:0002024 A method where the sample is first subjected to column chromatography where the mobile phase is a liquid, the stationary phase consists of very small particles and the inlet pressure is relatively high. The sample passes through two columns (anion and cation exchange) in series. The eluent is then subjected to mass spectrometry where it is ionised by interaction (electron or proton transfer) with reagent (N2, O2, H2O) gaseous ions at atmospheric pressure, and then analysed by two mass spectrometers in series. https://orcid.org/0000-0001-5985-7429 tandem dual-column HPLC-APCI-MS/MS