The separation of no carrier added [18F]fluoride from 18O enriched water is described. The [18F]fluoride is deposited on Dowex 1 x 10 anion exchange resin as the water is passed through. The 18F is removed by elution with a dilute solution of cesium carbonate or potassium carbonate in water. Recovery of the 18F is greater than 95% efficient with a loss of 18O water of less than 5 microL from a volume of 3 mL.