- Use these concentrators for general purpose anion concentration for high-purity water analysis - Use the Thermo Scientific Dionex IonPac TAC-LP1 Trace Anion Concentrator Column for low-backpressure operation 60 psi at 2mLmin and the Thermo Scientific Dionex IonPac TAC-ULP1 Trace Anion Concentrator Column for ultralow pressure operation 30 psi at 2mLmin