Hanna Instruments HI 83218 - Manual (Page 25)

25 Nitrate
• Replace the cap and immediately shake vigorously up
and down for exactly 10 seconds. Continue to mix by
inverting the cuvette gently for 50 seconds, while
taking care not to induce air bubbles. Powder will not
completely dissolve. Time and way of shaking could
sensitively affect the measurement.
• Reinsert the cuvette into the instrument, taking care
not to shake it.
• Press Timer and the display will show the countdown
prior to the measurement or, alternatively, wait for
4 minutes and 30 seconds and press Read. When the
timer ends the meter will perform the reading. The
instrument displays the results in mg/L of nitrate-nitrogen.
• Press or to access the second level functions.
• Press the Chem Frm key to convert the result in mg/L of nitrate (NO
3
¯).
• Press or to return to the measurement screen.
INTERFERENCES
Interference may be caused by:
Ammonia and amines, as urea and primary aliphatic amines
Chloride above 100 ppm
Chlorine above 2 ppm
Copper
Iron(III)
Strong oxidizing and reducing substances
Sulfide must be absent