17
Highly buffered samples (alkalinity above 500 ppm) or with extreme pH may exceed the buffering
capacity of the reagent: neutralize acidic samples with diluted NaOH or alkaline samples with
diluted HCl, prior to addition of the reagent.
Turbidity must be removed by prior filtration.
The following ions may cause negative errors:
cupric ions (Cu
2+
): above 5 ppm
ferrous ions (Fe
2+
): above 1 ppm
ferric ions (Fe
3+
):
above 2 ppm
INTERFERENCES
MEASUREMENT PROCEDURE
• At the end of measurement, the instrument directly displays concentration in mg/L of nitrogen‑
nitrite (NO
2
¯‑N) on the LCD.
• To convert the NO
2
¯‑N concentration to the nitrite ion concentration (NO
2
¯), multiply the reading
by factor of 3.29.
• To convert the NO
2
¯‑N concentration to sodium nitrite concentration (NaNO
2
), multiply the
reading by factor of 4.93.
Alternatively, wait for 15 minutes and just press
READ /TIMER
.
In both cases, the lamp, cuvette and detector icons will appear on the display, depending on
the measurement phase.