Nitrate colorimetric measurements

Measuring the concentration of NO₃ in a cell growth experiment using Spectroquant kit

Material: • Nitrate Test Kit (#09713)

The liquid test solution should be performed to achieve a measurement between the ranges of 1-25 mg/L NO3-N. Nitrate solution Prepare solution with 12.5 mg NO₃-N/L • Weigh 163mg Potassium Nitrate into 100mL volumetric flask • Fill flask with 100mL demineralized water and dissolve to achieve a concentration of 226 mg N/L • Pipette 2.76ml of the solution into 50 ml of demineralized water to achieve final concentration Performing Measurements: Nitrate solution Measuring range of the kit: 1-25 mg/L NO₃-N

1. Pipette 4.0 ml of reagent 1 (NO₃-1) into a test tube.
2. Add 0.50 mL of sample when it is among the range of measuring kit (otherwise make proper dilution) Do not mix.
3. Add 0.50 mL of reagent 2 (NO₃-2).
4. Mix.
5. Reaction time: 10 mins.
6. Pour sample into cuvette.
7. Select method in the spectrometer by entering the AutoSelector (little black tube).
8. Note result.
9. If the read is above the linear range then put the sample back to the tube test, dilute it if needed and try again.
10. If the nitrate test is not in the range make sure that nitrite is not above 5 mg/L and dissolve the sample with amidosulfuric acid. Adjust the pH between 1-3.