The development of an on-chip micro-flow injection analysis of nitrate with a cadmium reductor

摘要: Abstract The development of a method to determine nitrate by micro-flow injection analysis (μFIA) is described, using electro-osmotic flow (EOF) control in micro-chip with 300 μm wide and 115 μm deep channel wet etched borosilicate glass. An situ miniature copperised cadmium reductor column was produced immobilisation within micro-porous silica frit made from 10% formamide 21% silicon dioxide. located the sample introduction reservoir device. Nitrate standards were placed sampling an applied voltage 50 V relative waste used move ions through for μFIA. Silica frits without also introduced into interconnecting channels μFIA device promote EOF minimise hydrodynamic movement solutions. nitrite on leaving detected Griess diazo-coupling reaction. reaction monitored micro-spectrometer. A calibration obtained between 0.5 20 μM correlation coefficient 0.985. R.S.D. at 5 μM NO 3 − 8.3% ( n =6) limit detection (3 σ ) 0.51 μM (0.026 μg ml −1 .