LIMS.eu

As a summarizing effect and substance characteristic, the determination of Chemical Oxygen Demand (COD) is a typical parameter in the fields of environmental analysis, environmental control, environmental engineering, and technology and surveying (accreditation standards DIN 38409 / DIN 38414).

The measured value for COD can be included for the Biochemical / Biological Oxygen Demand after n days (BODn) or after 5 days (BOD5) for assessing water quality, wastewater pollution, or for evaluating water analyses (OENORM EN 1899 / OENORM M 6277 / DIN EN 1899 / ISO 5815:1989) or DOC, and if necessary, put into relation.

For example, the COD in the Result column is calculated by dividing the Raw Value by 1000. To calculate the DOC, the COD - Result is multiplied by 12 and the product is divided by 32. The Result for BOD5 is obtained by multiplying the COD - Raw Value by 0.35416.
In mathematical notation, the calculation looks as follows:

Parameter COD

Raw Value \/ 1000 = Result

(140 \/ 1000) = 0.14 or (150 \/ 1000) = 0.15

Parameter DOC

Raw Value (COD) * 12 \/ 32 = Result

140 * 12 \/ 32 = 52.5 or 150 * 12 \/ 32 = 56.25

Parameter BOD5

Raw Value (COD) * 0.35416 = Result

140 * 0.35416 = 49.58 or 150 * 0.35416 = 53.12

In the Labordatenbank notation, the abbreviation of the parameter whose value is used for the calculation and the column number where the respective measured value is located are specified.

Parameter COD
Raw Value = ['COD']['0']
Result = ['COD']['0'] \/ 1000

Parameter DOC
Result = ['COD']['0'] * 12 \/ 32

Parameter BOD5
Raw Value = ['BOD5']['0']
Result = ['COD']['0'] * 0.35416

The formula is stored in the Formula Field of the column where the result should appear.
To access the mask for storing formulas, click on the blue-written name of the parameter, e.g., COD - Chemical Oxygen Demand.

The COD is expressed in milligrams per liter (mg/l) and indicates the mass of oxygen consumed per liter of solution.

m['CSB']['0'] / 1000

To calculate the dissolved organic carbon (DOC), the COD result is multiplied by 12 and the product divided by 32.

m['CSB']['0'] * 12 / 32

The result for BOD5 (biological oxygen demand after 5 days) is obtained by multiplying the raw COD value by 0.35416.

m['CSB']['0'] * 0.35416

Further details can be found under Deposit formulas with parameters.