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COD Testing Procedure Guide

This document outlines the procedure for measuring chemical oxygen demand (COD) using a DRB200 Reactor. Key steps include homogenizing the water sample, adding it to a COD reagent vial along with a blank vial, heating the vials for 2 hours, allowing them to cool, and then using colorimetric determination to read COD concentrations in mg/L. The document also discusses using various water samples like river, pool, drainage, and tap water to obtain COD results.

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akmal hazim
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93 views5 pages

COD Testing Procedure Guide

This document outlines the procedure for measuring chemical oxygen demand (COD) using a DRB200 Reactor. Key steps include homogenizing the water sample, adding it to a COD reagent vial along with a blank vial, heating the vials for 2 hours, allowing them to cool, and then using colorimetric determination to read COD concentrations in mg/L. The document also discusses using various water samples like river, pool, drainage, and tap water to obtain COD results.

Uploaded by

akmal hazim
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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Oxygen Demand, Chemical

Apparatus
1. Beaker, 250-ml

2. Blender

3. COD Digestion Reagent vials

4. DRB200 Reactor

5. Light Shield or adapter (see instrument-specific Information)

6. Magnetic stirrer and stir bar

7. Opaque shipping container for storage of unused, light-sensitive reagent Vials

8. Pipet. TenSette, 0.1 to 1.0 ml, with tips (for 200-15,000 mg/l range)
9. Pipet. volumetric, 2.00 ml.

10. Pipet Filler, safety bulb

11. Test Tube Rack

Reactor digestion procedure


1. Homogenize 100 mL of sample for 30 seconds in a blender. For samples containing large
amounts of solids, increase the homogenization time.If the sample does not contain
suspended solids,omit steps 1 and 2.

2. For the 200-15,000 mg/L range or to improve accuracy and reproducibility of the other
ranges, pour the homogenized sample into a 250-ml beaker and gently stir with a magnetic
stir plate.

3. Turn on the DRB200 Reactor. Preheat to 150 °C. See the DRB200 User Manual for
selecting pre-programmed temperature applications.
4. Remove the caps from two COD Digestion Reagent Vials. (Be sure to use vials for the
appropriate range.)

5. Prepared Sample: Hold one vial at a 45-degree angle. Use a clean volumetric pipet to add
2.00 mL of sample to the vial. For the 200-15,000 mg/L vials: Use a TenSette Pipet to add
0.20 mL of sample to the vial.

6. Blank Preparation: Hold a second vial at a 45-degree angle. Use a clean volumetric pipet to
add 2.00 mL of deionized water to the vial. For the 200-15,000 mg/L vials: Use a TenSette
Pipet to add 0.20 mL of sample to the vial.

7. Cap the vials tightly. Rinse them with water and wipe with a clean paper towel.

8. Hold the vials by the cap over a sink. Invert gently several times to mix. The sample vials
become very hot during mixing. Insert the vials in the preheated DRB200 Reactor. Close the
protective lid.

9. Heat the vials for two hours.

10. Turn the reactor off. Before removing the vials, wait about 20 minutes for the vials to
cool to 120 °C or less.
11. Invert each vial several times while still warm.
12. Place the vials into a rack and cool to room temperature. Proceed to Colorimetric
determination.

Colorimetric determination procedure


1. Select the test. Insert an adapter or light shield if required (see Instrument-specific
information). Refer to the user manual for orientation.

2. Clean the outside of the vials with a damp towel followed by a dry one.

3. Insert the blank into the 16-mm cell holder.

4. ZERO the instrument. The display will show:


0 mg/L COD
Or
0.0 mg/L COD
5. Insert the sample vial into the 16-mm.

6. READ the results in mg/L COD.


7. If using High Range Plus COD Digestion Reagent Vials, multiply the result by 10. For
most accurate results with samples near 1500 or 15,000 mg/L COD, repeat the analysis with a
diluted sample.

Discussion:
We used 5 types of water samples, namely river water, pool water, drainage, rainwater and tap
water to conduct different studies and to obtain different results table-based result.

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