Are there instructions for BOD Standard Solution, 3000 mg/L Voluette® Ampules using the Respirometric Method?

Document ID

Document ID TE3239

Version

Version 3.0

Status

Status Published

Published Date

Published Date 09/18/2018
Question
Are there instructions for BOD Standard Solution, 3000 mg/L Voluette® Ampules using the Respirometric Method?
Summary
BOD Standard Solution, 3000 mg/L Voluette® Ampule Instructions
Answer
Instructions for using the BOD Standard Solution, 3000 mg/L, pk/16 - 10-mL Voluette® Ampules (Product # 1486610) can be found in the BODTrak™ II user manual.

This standard is required to verify the accuracy of Biochemical Oxygen Demand (BOD) measurements using the BODTrak™ II. The procedure is equivalent to Standard Methods 5210 D - Respirometric Method. Unlike the Dilution Method for BOD, where a 150 mg/L Glucose and Glutamic Acid (GGA) standard is ultimately diluted to 3 mg/L, the Respirometric Method is run on directly on a 150 mg/L GGA standard. Built into the BODTrak™ II test procedure for this standard, is a dilution factor of 20 (the 3000 mg/L GGA standard is ultimately diluted to 150 mg/L as specified in Standard Methods).

When testing the GGA standard, a seed blank is run in parallel. Always prepare the seed blank before the GGA samples. Use the same amount of seed for all GGA samples and the seed blank. If the seed strength is unknown, use 20 mL. Adjust the seed volume as necessary to achieve the optimum GGA results.
  1. Add approximately 30 mL of deionized water to a 200-mL graduated cylinder.
  2. Use a volumetric pipet to move 8.0 mL of standard to the graduated cylinder (Skip this step when the seed blank is prepared).
  3. Add the contents of one nutrient buffer pillow to the graduated cylinder.
  4. Use a pipette to add the correct quantity of seed to the graduated cylinder.
  5. Dilute the mixture to the 160 mL mark with deionized water.
  6. Move the mixture from the graduated cylinder to a BODTrak™ II bottle and incubate.
  7. The expected BOD result will be 235 +/- 11 mg/L.
The result of 235 +/- 11 mg/L BOD differs from the expected result listed in Standard Methods, 260 +/- 30 mg/L. Standard Methods only gives basic recommendations and guidelines for overall test setup and procedure. Inherent differences among seed culture and respirometers will cause variation in results. Standard Methods recommends checking the manufacturer's instructions for specific instrument requirements and operating characteristics. Thorough testing and evaluation at Hach showed that a mean value of 235 mg/L BOD is the expected operating characteristic for the BODTrak™ instrument.
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