Method 4: Nitrate as Nitrogen with Spectrophotometer, HACH DR 2010/2000

Method 8171

Purpose/Objectives :

To measure the nitrate ion concentration in water samples while in the field or in the lab. Samples are analyzed using a HACH spectrophotometer. The instrument uses a stored calibration curve, requiring only a reagent blank. Data is reported as mg/L NO3-1-N.

Equipment and Materials

  • HACH DR 2010/2000CBL System
  • deionozed water
  • 25 mL matched cells
  • HACH NitroVer 5 Nitrate Reagent Powder Pillows
  • cell stopper

Sample Collection and Preservation

1.25 mLs of water sample is required for each analysis.

2.To obtain a representative sample:

  • Collect sample from below surface of water.
  • Sample from as far away from shore as is safe. Use a sampling device made of a rod and container if necessary.

3.Samples held for off-site testing within a few hours should be refrigerated.

Safety Alert:

1.HACH NitroVer 5 Nitrate Reagent Powder Pillows contain the heavy metal cadmium, a known carcinogen; extremely toxic by inhalation of dust or fumes.

2.Use extreme care when handling this reagent!

Analysis Procedure

1.Enter the stored program number “353” for medium range NO3-1-N. Press ENTER.

2.Rotate wavelength dial to 400 nm. The display should prompt to “Zero Sample.” Then display will read “mg/L NO3-1-N.”

3.Fill sample cell with 25 mL of sample. Fill another sample cell with 25 mL of deionized water.

4.Add contents of 1 NitroVer 5 Nitrate Reagent Powder Pillow to each cell. Stopper.

5.Press SHIFT TIMER . A one minute reaction time will begin. Shake until timer beeps.

6.When timer beeps press SHIFT TIMER . a five minute reaction timewill begin.

7.When timer beeps, display will show “mg/L NO3-1-N.” Remove stopper from blank; place blank into cell holder; close light shield.

8.Press ZERO. the display will show “Zeroing…” then it will show

“0.0 mg/L NO3-1-N.”

9.Remove blank and replace with cell of prepared sample. Close light shield.

10. Press READ. The display will show “Reading…”, then the result as mg/L NO3-1-N.

11.Record concentration values to the nearest 0.1 mg/L NO3-1-N on Data and Calculations Log Sheet.

Waste Disposal

1.Dispose of waste as instructed by supervisor.

References

WaterAnalysisHandbook, 3rd Edition, HACH Company, Loveland, Colorado, 1997.

DATA AND CALCULATIONS LOG SHEET

Method 2: Nitrate-Colorimeter with Multiple Standards

Student Team:______Hour:______

Student Name:______

Student Name:______

Student Name:______

Stream or lake sampled:______Sample Date:______

Site Name:______Sample Time:______

Site Number:______Sampled By:______

Column /

A

Reading / NO3-1-N
(mg/L)
1
2
Average Nitrate (mg/L NO3-1-N)

Column Procedure:

A.Record NO3-1-N concentration as direct reading from instrument. MDL = 0.1 mg/L NO3-1-N Linear range = 0 – 4.5 mg/L NO3-1-N

Field Observations:

______

Analysis Date:______Analysis Time:______

Analysts:______