A new and improved NTA workflow has been successfully developed and applied to selective identification of acidic substances in drinking water using SAX-SPE and mixed-mode RP-AX LC-HRMS for the first time. This new approach was shown to offer broadly better recovery, offered fewer matrix effects and better selectivity for detection and quantification of a selection of 23 diverse substances including PFAS, HAAs, artificial sweeteners, acid herbicides and other industrial acidic chemicals in comparison to more a conventional mixed-mode WAX-SPE approach. The ability to consistently recover strong acids from SAX-SPE was enabled by use of ammonium bicarbonate eluents in SPE; this additive is quantitatively removed by evaporation (allowing LC-MS analysis) and offers a nearly-neutral pH extract for potentially enhanced analyte stability. We believe that such innovation could find broad application in qualitative and quantitative analysis of organic acids.