Biochemical Oxygen Demand Standard Method 5210

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Amendments for Standard Methods 5210 22nd and 23rd Edition

The following list summarizes the differences between the 22nd and 23rd editions of the Biochemical Oxygen Demand Standard Method 5210. Download the PDF here.

5210 A. Introduction
22nd Edition (2001) 23rd Edition (2017)
The seeding and dilution procedures provide an estimate of the BOD at pH 6.5 – 7.5 The seeding and dilution procedures provide an estimate of the BOD at pH 6 – 8
5210 B. 5-Day BOD Test
22nd Edition (2001) 23rd Edition (2017)
Apparatus
Mentions only the use of glass bottles Specifies that disposable plastic bottles are acceptable if they meet all method quality-control checks
Does not specify type of dissolved oxygen probe Specifies that an oxygen-sensitive membrane electrode or oxygen-sensitive optical probe may be used
Reagents
Use reagent grade or better for all chemicals and use distilled or equivalent water, preferably sterilized for making all solutions Use reagent grade or better for all chemicals and use distilled or equivalent reagent grade water, for making all solutions
Allylthiourea (ATU) solution cannot be stored for more than 2 weeks Allylthiourea (ATU) solution cannot be stored for more than 2 weeks at ≤ 6°C without freezing
Store all GGA mixtures at ≤ 4°C Store all GGA mixtures at ≤ 6°C without freezing, unless manufacturing states otherwise
Preparatory Procedures
Keep grab and composite samples at ≤ 4°C between collection / composition and analysis if hold time is greater than 2 hours Keep grab and composite samples at ≤ 6°C between collection / composition and analysis if hold time is greater than 2 hours
Do not analyze samples after 24 hours Recommended hold time is 24 hours; however, the US EPA allows for a 48-hour hold time
Adjusted pH of samples between 7.0 – 7.2, if required Adjusted pH of samples between 6.5 – 7.5, if required
Testing Procedures
Five dilutions are recommended if experience with a particular sample does not produce at least three bottles having acceptable minimum DO depletions and residuals limits Two dilutions are allowed if experience with a particular samples source produces at least one bottle with acceptable minimum DO depletions and residual limits
For dilutions greater than 1:100, make a primary dilution before making final dilution in the bottle For dilutions greater than 1:300, make a primary dilution before making final dilution in volumetric cylinders or flasks
Data Analysis and Reporting
Not Applicable If all dilutions result in a DO depletion of <2.0mg/L and the sample was diluted, select the bottle with the largest volume (least diluted) and calculate the report as if the dilution had depleted 2.0mg/L
Precision and Bias

Detection limits are established by the minimum DO depletion and minimum DO residuals as follows:

  • The lower detection limit for unseeded samples that require dilution is 2 mg/L multiplied by the dilution factor as established by the requirement for a minimum DO depletion of 2 mg/L
  • The lower limit for seeded samples that require dilution is ~1 mg/L as established by the minimum depletion of 2 mg/L minus the maximum seed correction which should be < ~1mg/L
  • The lower limit for unseeded samples that require no dilution is equal to the detection limit of the DO measurement method (~0.1 mg/L)
  • The lower detection limit for seeded samples that require no dilution is 0 mg/L as established by the difference between the sample DO depletion and the seed correction

Reporting limits are established by the minimum DO depletion and minimum DO residuals as follows:

  • The lower reporting limit for unseeded samples that require no dilution is equal to the detection limit of the DO measurement method (~0.1 mg/L)
  • The lower reporting limit for seeded samples that require no dilution – except for seed, nutrient, mineral, and buffer solutions (S>0, P=1) – is the difference between the sample DO depletion and the seed correction

 

 

 

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