An integrated microdistillation flow injection system for nitrite measurement

The development of an on-line nitrite preconcentration system, based on distillation of nitrous acid using a microdistillation technique is reported. The incorporation of microdistillation into a flow injection manifold gives rise to an analytical technique, microdistillation flow injection analysis (MDFI), which has several distinct advantages. This method has high throughput (15 samples/h), small sample volume (6.0 ml) and low detection limit (5 μg/l). A further advantage is the use of a non-specific pH electrode as the sensing device. The system showed good selectivity to nitrite with respect to some other possible interfering anions. No interference is observed from chloride, fluoride, carbonate and sulfate and only slight interference from sulphide and sulfite ions.