TITLE: Chemical Oxygen Demand (COD) Protocol
AUTHORS: William Brigman

[DESCRIPTION]
<div class = "text-blocks"><div class = "text-block"><span>Version 2.0 (COD station 1</span><span style = "vertical-align:super;">st</span><span> lab and analytical trailer)</span></div><div class = "text-block"><span style = ":UNDERLINE;">Developed by</span><span>: William Brigman 9-25-2014; Filename: COD protocol v2.0.doc</span></div><div class = "text-block"><span style = ":UNDERLINE;">Certified by</span><span>: Matias Vanotti 8-4-2011</span></div><div class = "text-block"><span style = ":UNDERLINE;">Experts</span><span>: William Brigman (ext. 302) </span></div><div class = "text-block">Revised: 1/18/2017</div></div>

[STEPS]
?. Fill out the COD data sheet, record the sample identification number and COD vial number.
?. For samples with moderate to low COD (such as constructed wetlands) use the 1,500 mg/L COD vials.For samples with high COD (such as lagoons) use the 15,000 mg/L COD vials.
?. Turn on COD block heater digester (DRB 200-HACH) (toggle switch on back) and allow it to reach set temperature (~20 minutes).
?. If using 1,500 mg/L COD vials, use 2mLof sample (measured by pipette).If using 15,000 mg/L COD vials, use 0.2mL of sample (measured by pipette).
?. Use the COD standard (1000 mg/L) located in the refrigerator.Pipette 2mL of standard into a 1,500 mg/L COD vial and 0.2mL into 15,000 mg/L COD vial.
?. For a blank, pipette the appropriate amount of deionized water into COD vial.
?. Remember to shake your samples and standards up before sampling them so that we get a uniform sample.
?. For a QA/QC check sample, get the COD standard (300 mg/L and/or 800 mg/L) from the refrigerator to use as a check.
?. After adding sample, put cap back on tight and shake COD vials to mix the sample.
?. You should always have at least 1 blank, 2 standards, and 1 QC check.
?. Place vials in COD block heater.Set timer on COD block heater for 2 hours.
?. After 2 hours, let the vials cool in the block heater for 10 minutes and then remove the vials from the block heater, place in a dark area, and allow the vials to cool. Caution, these will be hot!!!! Allow to cool for 10-15 minutes.
?. After COD vials have cooled, wipe off COD vial with a kimwipe to remove any fingerprints and smudges:
?. [Genesys 20 Colorimeter]
Place the blank COD vial into the COD reader, press “zero” on the colorimeter keyboard. This will set the blank. The blank should read 0 mg/L.
?. [Genesys 20 Colorimeter]
Next, place the vial containing the 1000 mg/L standard into the colorimeter.Press read and record the valve.
?. [Genesys 20 Colorimeter]
Measure COD values for all standards, samples, and QAQC standards. Follow the same procedure in step 15 for each sample. Record colorimeter data on the COD data sheet. The output will be in mg/L.
?. [Genesys 20 Colorimeter]
After completion of measurements, turn off COD block heater and COD colorimeter.
?. [DR-2700 Colorimeter]
Press button on the back of colorimeter to turn on and allow 30min to warm-up.
?. [DR-2700 Colorimeter]
The colorimeter will go thru a self check once when its first turned on.
?. [DR-2700 Colorimeter]
After 30min, click on “Favorite Program” button and select the correct program. The program we are using is “435 COD HR 1500 mg/L.”
?. [DR-2700 Colorimeter]
Once selected hit start.
?. [DR-2700 Colorimeter]
Next hit “options” button and change the current units to mg/L (hit 3rd button down from the top unit the correct units are displayed on the big screen).
?. [DR-2700 Colorimeter]
Insert the blank vial and press “zero”, wait for beep and reading to be displayed.
?. [DR-2700 Colorimeter]
Insert the standard vial and press “read”, record value and continue into all samples have been analyzed.
?. [DR-2700 Colorimeter]
Hold button on back of colorimeter to turn off.
?. See WASTE DISPOSAL section under Guidelines.