Nitrites: Procedure

  1. Take out samples and nitrate kit.
  2. Using a blank piece of paper, create a column for each site, and then two rows (one each for the calibration and test samples). After each vial is completed, place in appropriate spot and record time on paper.
  3. For each sampling site, prepare one calibration vial and one test vial.
    a. Calibration Sample Procedure
    • Using a clean vial, add 5 mL of sample and then 5 mL of DI water.
    • Screw on the cap, and set vial on chart.
    b. Test Sample Procedure
    • Using a clean vial, add 5 mL of sample and then 5 mL of DI water.
    • Add one NITRATE HR-1 tablet to the 10 mL solution. Using a clean stir rod, crush tablet and allow to dissolve completely.
    • Add one NITRATE HR-2 tablet to the same 10 mL solution. Using a clean stir rod, crush tablet and allow to dissolve completely.
    • Screw on the cap, set vial on chart, and record time.
  4. After test vial has been allowed to sit for 10 minutes, turn on Orion AQUAfast II. Display should read “no3”, if not press “mode” until it is displayed.
  5. Place corresponding calibration vial into the chamber and press “zero”. The “no3” display should flash then show “0.0.0”.
  6. Remove calibration vial and place test vial into chamber. Display should still read “0.0.0”. Press “test”, the screen should flash “no3” then display either a value (the sample’s nitrate level in mg/L) or “-Err” (the sample’s nitrate level is below the detection limit). Record result on data sheet and remove test vial from chamber.
  7. When next the next pair of calibration and test vials are ready, press the “mode” button to display “no3”, then repeat steps 5 -7 for each site.
  8. When done testing, turn off Orion meter and return to case.
  9. Wash all vials and other equipment used.

— The nitrate measurements have an inherent error of ± 5 mg/L.