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A new diffusive gradients in thin films (DGT) technique, using Purolite A520E anion exchange resin, was developed and evaluated for the measurement of NO₃single bondN in freshwaters. Purolite A520E had a very high uptake efficiency (>98%) and elution efficiency (82.7% with 2 mol L⁻¹ NaCl as eluent) for NO₃single bondN. The 24 h mass vs. time validation experiments had excellent linearity (R² ≥ 0.997) and the intrinsic capacity of the binding layer for NO₃single bondN was 849 ± 24 μg. NO₃single bondN uptake was quantitative over a pH (3.5–8.5) range typical of most natural freshwaters. Several anions competed with NO₃single bondN to produce a lower effective binding capacity for NO₃single bondN in the following order of selectivity, Cl⁻ > HCO₃⁻ > SO₄²⁻ > H₂PO₄⁻, although NO₃single bondN measurements were quantitative at ionic strengths 0.0001–0.008 mol L⁻¹ as NaCl. NO₂single bondN did …