Calculation of Partition Coefficients

In order to calculate partition coefficients you will first have to search for the chemicals of interest. As a second step you have to select the compounds which should be used to calculate the respective partitioning coefficients. If no compound of your query result is selected, all chemicals will be included in the calculations. In the last step you have to select the partition systems of interest. Only if at least one chemical and one system have been selected, a button will appear that enables you to calculate partition coefficients for all chemicals and all selected systems.

Calculation of the Extraction Efficiency

In order to calculate the fraction of an analyte that is extracted, one first has to search and select the analyte(s) in the database. If no chemical of the query result is specified by clicking on it, all chemicals returned in the query will be included in the calculations. Next, one has to select all solvents of interest from the list shown in the window. Finally one enters the volumes of the water sample to be extracted. The fraction of analyte in the solvent can be calculated for a given volume of solvent or for different solvent volumes. It is also possible to calculate the respective volume of solvent for a defined fraction of analyte in the solvent or to include a two-step extraction. Additional components in the water phase such as salts (salting-out), proteins and lipids, and organic matter can be considered in the calculations in any combination.

Biopartitioning

In order to calculate the biopartitioning of the analyte one first has to search and select the analyte(s) in the data base. If no chemical of the query result is selected, all chemicals will be included in the calculations. Next one has to enter the composition of the organism in terms of volume percentages of all components (serum albumin, muscle proteins, storage lipids, phospholipids and water).

Freundlich Koc

Non-linear sorption isotherms for soil organic carbon/water partitioning can be described by a Freundlich isotherm. The calculated partition coefficient from the respective ppLFER equation is only valid for aqueous concentrations in the range of 0.03 mmol/L. Often the aqueous concentrations are different to this value. For these concentrations we offer a calculation tool based on the Freundlich isotherm.

Thermodesorption

In order to trap an analyte quantitatively from air to a sorbent the type and amount of sorbent that is used has to be adjusted to the sampling temperature and volume as well as the type of analyte in order to avoid breakthrough. In the subsequent desorption step, temperature and gas volume have to be adjusted to the type and amount of sorbent and the type of analyte. All this can be planned ahead provided that the sorption constants of the analyte on potential sorbents are known as a function of temperature - information that is contained in our database. Hence, we provide tools to calculate a) the sorbent mass required for quantitative trapping, b) the temperature required for quantitative desorption into a specified gas volume and c) as a general information, the volume of gas per gram sorbent at which 50% of the analyte will break through a sorbent column, BTV50% (for 4 different sorbents) at the specified temperature.

Calculation of the passive Caco-2/MDCK Permeability

In order to calculate the membrane permeability you will first have to search for the chemicals of interest. As a second step you have to enter some experimental details: we recommend that you enter the individual thickness of the unstirred water layers on both sides of the cell layer; alternatively you can also enter the total thickness of the unstirred water layers on both sides of the cell layer (total UWL thickness is sufficient for the calculation if the iso-pH method is used), and the individual layers will be assumed symmetrical. In the exported spread sheet you have to specify the percentage of the neutral species of each chemical in the calculation for all aqueous layers (apical UWL, cytosol, basolateral UWL). The default value is 100% (for non-ionizable chemicals). If you are interested in acids or bases, then the respective number for the percentage of the neutral species has to be entered in the exported spread sheet and all subsequent calculations will use this fractionation information. The entered neutral fractions must be greater than zero. The calculated permeability refers to the total concentration of the chemical, assuming that the ionic species does participate in the permeation through the unstirred water layer and the paracellular pathway but not to the transport through the membrane itself.

Cfree

In order to calculate the freely dissolved fraction or concentration of a solute one first has to search (and select) the solute(s) in the database. Subsequently you have to decide between different options: Option1 calculates the freely dissolved concentration/fraction in plasma. Option 2 calculates the freely dissolved concentration/fraction in a selection of cellular assays. Here you must select a specific combination of medium, serum and cell line from a list. The differences between the different options happen to be rather small, so that you might chose any selection to still receive a good estimate for any assay that does not match the components in the list. Also, the cell number is of little influence so that any rough estimation will do. Option 3: Here you can specify any solution/suspension for which you want to calculate Cfree. It is important to note that all results for Cfree only refer to neutral species. Cfree for ionic species or ionizable chemicals cannot be calculated with these tools.

Preconcentration in a gas stream

With this tool, one can calculate the percentual loss of analyte that occurs during preconcentration of a solvent extract with nitrogen at 25°C. Again one first has to search for the analyte in the database. Among the results one has to select one for which all descriptors are present. Afterwards one can go to the blow-down menu and select the type of solvent and the volumina before and after blow-down.

Search for neutral chemicals

Source:

Search for partition systems

Most frequently used

Bio Materials





Technical Sorbents



carbonaceous sorbents

Solvent water


Water



Calculate the biopartitioning

vol %
vol %
vol %
vol %
vol %
vol %
* muscle protein is pure muscle protein without lipids

** carbohydrates, minerals ...
** this is not accounted for as a partitioning phase

Calculate the sorbed concentration


Calculate the extraction efficiencies

Name Id
1,2-dichloroethane 1
1-chlorobutane 2
2-methyl-1-propanol 4
2-methyl-2-propanol 5
3-methyl-1-butanol 6
acetophenone 7
aniline 8
benzene 9
benzonitrile 10
bromobenzene 11
butan-1-ol 12
butane 13
butyl acetate 14
carbondisulfide 15
chlorobenzene 17
chloroform 16
cyclohexane 18
decan-1-ol 19
dibuthylether 20
dibutylether 21
dichloromethane 22
diethylether 23
diisopropylether 24
ethyl acetate 25
ethylbenzene 26
fluorobenzene 27
heptan-1-ol 28
hexan-1-ol 29
iodobenzene 30
isobutanol 31
isooctane 32
isopropylmyristate 33
methylcyclohexane 34
methylisobutylketone 35
n-decane 36
n-dodecane 37
n-heptane 38
n-hexadecane 39
n-hexane 40
nitrobenzene 41
N-methylpyrrolidinone 42
n-octane 43
nonan-1-ol 44
n-undecane 45
octanol 3
oleylalcohol 47
olive oil 48
o-nitrophenyloctylether 49
pentan-1-ol 50
pentane 51
perfluoro-hexan, -heptane, -octane 52
PGDP 53
tetrachloromethane 54
toluene 55
trichloromethane 57
triolein 58

Calculate the fraction of solute in the solvent for a given solvent volume


Calculate the fraction of solute in the solvent for various solvent volumes


Calculate the solvent volume for a given fraction of solute in the solvent




Water contains:


Salts

Proteins and lipids

Equations for serum albumin and storage lipids are applied

Organic matter

Calculate optimal parameters for thermodesorption

L
°C
mL g
°C

Calculate the maximal loss of solute during solvent blow down with nitrogen

Calculate the permeability through a Caco-2/MDCK monolayer

The fraction of neutral species at experimental pH can be entered in the exported excel sheet

Calculate the concentration of freely dissolved analyte
ONLY FOR NEUTRAL MOLECULES!

Option 1: Cfree in plasma

Option 2: Often used assays

µL
%
%

Option 3: Custom made assay

mL
mL
mL
mg
mg
%
%

Please cite this database as:
UFZ-LSER database v4.0 [Internet], Leipzig, Germany, Helmholtz Centre for Environmental Research-UFZ. 2025 [accessed on 03.04.2026]. Available from https://www.ufz.de/lserd

Citation LSERD Terms of use

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Only valid for neutral chemicals. For more details about the domain of applicability for each descriptor see Excel Export.
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