Hach-Lange BODTRAK II: Respirometric Biochemical Oxygen Demand (BOD) - Manual (Page 30)

BODTrak™ II procedures
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5.5.1 Determination of results
After the end of the chosen test period (5, 7 or 10 days), END is shown on the
display. The procedure that is done dictates the determination of the results. The
results are determined based on the selected procedure: Simplified, Hach GGA or
Hach Standard Method.
5.5.1.1 Simplified sample results
The Simplified Procedure results are shown on the BODTrak II display. Push the
applicable channel selection key to show the results.
Note: If the sample was pre-diluted, apply a dilution factor to the instrument reading
(
section 5.7.1 on page 33 ).
5.5.1.2 Hach GGA (glucose/glutamic acid) results
The seed blank and seeded GGA sample results are necessary for the Hach GGA
procedure results.
1. Push the channel selection key for the seed blank bottle. The results are
shown.
2. Push the channel selection key for the seeded GGA sample bottle. The results
are shown.
3. Calculate the results:
BOD mg/L = seeded GGA sample result - seed blank result
5.5.1.3 Hach Standard Method results
1. Push the channel selection key for the Hach Standard Method sample bottle.
The results are shown.
Note: Treat the seed blank the same as all other samples.
Note: If the sample was pre-diluted, apply a dilution factor to the instrument reading
(
section 5.7.1 on page 33 ).
2. Find the dilution factor based on the selected range ( Table 6 on page 24 ).
Example: If the sample range selected was 0 to 350 mg/L BOD, the dilution
factor is 1.45.
3. Calculate the corrected results:
BOD mg/L = BOD mg/L (instrument reading) x dilution factor
Example:
Instrument Reading = 200 mg/L, BOD dilution factor = 1.45
200 mg/L x 1.45 = 290 mg/L BOD (Corrected Result)