FIGURE 4. Recorded peaks and calibration plots for nitrate+nitrite
determined simultaneously by the CdR-reduction (a) and NaRreduction
(b) methods. Calibrants contain 80% nitrate-nitrogen and
20% nitrite-nitrogensfor example, calibrant 2, which has a nominal
concentration of 3.75 mg-N/L, contains 3.0 mg of NO3
- -N/L and 0.75
mg of NO2
- -N/L. Sampling rate is 90 h-1 (sample time ) 30 s, wash
time)10 s). Reduction of nitrate to nitrite by (a) packed bed cadmium
reactor (dwell time ) 165 s) and (b) soluble NaR (dwell time ) 930
s).