Flow-injection biamperometry for direct determination of hydroxylamine at two pretreated platinum electrodes

Flow-injection biamperometry is used for the direct determination of hydroxylamine based on coupling two independent and irreversible electrode processes, the oxidation of hydroxylamine and the reduction of platinum oxide. In operation a potential difference of 0V is imposed between two platinum wire electrodes pretreated by an anodization step, and the resulting current is measured. Hydroxylamine can be determined in the range of 6×10-7 to 4× 10-5moll-1 with the detection limit of 1×10-7moll-1. Nitrogen-containing compounds such as nitrate, nitrite and ammonia that often accompany hydroxylamine in the process of nitrogen cycle do not cause significant interference. The stability of the detector is shown by a relative standard deviation (R.S.D.) of 1.4% for 50 replicate determinations of 1×10-5moll-1 hydroxylamine.