Registration Dossier

Environmental fate & pathways

Adsorption / desorption

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Koc = 58119 L/kg (geometric mean of 5 soils), OECD guideline 106, GLP

Key value for chemical safety assessment

Koc at 20 °C:
58 119

Additional information

The adsorption and desorption of DOPA-Glycinate was investigated according to OECD guideline 106. The study was performed using 14C-labelled representative lead components (C12 moiety) of the test substance. The average adsorption/desorption behaviour of the test substance was determined by measuring total 14C-radioactivity without differentiation of the single components of the test substance. Five soils with different content of organic carbon and clay were selected. The adsorption of the test substance onto each of the five soils was a rapid process: The results of the adsorption kinetics revealed that in most cases the adsorption equilibrium was reached already after 1 hour. Percentage of adsorbed 14C-radioactivity (mean values) were in the range of 85.8 % to 96.0 %. Calculated adsorption coefficients (KFads) were in the range of 853.3–2428.8

The desorption experiments showed that the adsorption was only marginally reversible. Only 4.7–7.7 % of the adsorbed test substance were desorbed. Calculated desorption coefficients (KFdes) were in the range of 1350.2–3183.5. According to SSLRC mobility classification, DOPA-Glycinate can be classified as non-mobile (KOC> 4000 mL/g).

 

Adsorption/desorption of DOPA-Glycinate to/from soils:

Guideline/ test method: OECD 106, EU C. 18

Adsorbed a.s. (%)

Ka1

KaOC2

Kd3

KdOC4

Ka/Kd5

Soil 1:LUFA no.2.2, loamy sand

92.7

1254.9

54561

3183.5

138413

0.39

 

Soil 2:Marisfeld, clay loam

94.5

1296.6

51864

2110.6

84424

0.61

 

Soil 3:Osnabrück, loamy sand

95.2

2428.80

86743

2654.0

94786

0.91

 

Soil 4:Ebbinghof, silt loam

92.7

1203.1

31660

1350.2

35532

0.89

 

Soil 5:Borstel, sandy Loam

91.5

853.3

85330

1352.7

135270

0.63

 

1) Ka= Adsorption coefficient;

2) KaOC= Adsorption coefficient based on organic carbon content;

3)Kd= Desorption coefficient;

4) KdOC= Desorption coefficient based on organic carbon content;

5) Ka/Kd= Adsorption / Desorption distribution coefficient

From the KOC values for adsorption (KaOC) reported in the table above, the mean normalised KOC relevant for risk assessment is calculated as

KOC(geometric mean) = 58,119

Applying the formula

Kpcomp=Foc× Koc

according to the TGD, the following partition coefficients for soil, sediment and suspended matter were estimated:

           Kpsoil= 1164

           Kpsed= 2910

           Kpsusp= 5820