7-azatridecane-1,13-diamine

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

For details on endpoint specific justification please see read-across report in section 13 or find a link in cross-reference “read-across: supporting information

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

assessment report

Key result

Sample No.:

#1

Type:

Kd

Value:

201 L/kg

Temp.:

20 °C

Matrix:

soil (no. 1)

Remarks on result:

other: Kd not dependent on organic carbon

Key result

Sample No.:

#2

Type:

Kd

Value:

> 51 000 L/kg

Temp.:

20 °C

Matrix:

soil (no. 2)

Remarks on result:

other: Kd not dependent on organic carbon

Key result

Sample No.:

#3

Type:

Kd

Value:

18 333 L/kg

Temp.:

20 °C

Matrix:

soil (no. 3)

Remarks on result:

other: Kd not dependent on organic carbon

Key result

Sample No.:

#4

Type:

Kd

Value:

6 914 L/kg

Temp.:

20 °C

Matrix:

soil (no. 4)

Remarks on result:

other: Kd not dependent on organic carbon

Key result

Sample No.:

#5

Type:

Kd

Value:

152 L/kg

Temp.:

20 °C

Matrix:

river sediment (no. 5)

Remarks on result:

other: Kd not dependent on organic carbon

Validity criteria fulfilled:

yes

Conclusions:

Binding of BHT to soils was strong: Kd values were between 201 (soil I) and >51000 (soil II) L/kg (log Kd between 2.3 and >4.7, respectively), for the sediment sample the Kd value was 152 L/kg (log Kd 2.2).
Binding was not a function of organic carbon content of the soils. Rather, clay and silt content might be decisive.
Desorption was observed. However, within 120 h extent of desorption was limited and seems to be a slow process.

Executive summary:

The adsorption/desorption behaviour of BHT amine containing the main constituents BHT (64.8%) and HMD (13.8%) was investigated using four soil types covering a range of different soil properties: Speyer 2.1 (soil I, sand), Speyer 6S (soil II, clay), Empingham (soil III, clay loam), Mechtildshausen (soil IV, loam) and sediment of the River Rhine (soil V, sandy loam). Sorption of BHT to the investigated soils was strong but showed a dependency on the soil involved and on the soil-to-solution ratio used. Sorption was strongest to the clay soil (soil II) and weakest to the sand soil (soil I). With the exception of the river sediment (Soil V), sorption increased with increasing clay content. No correlation of sorption and the soil properties pH value, cation exchange capacity and organic carbon content was observed. The sorbed fraction of analyte increased with the amount of soil used in the batch systems. Apparent equilibrium distribution was reached within 48h. Desorption was investigated for 120h after the 48h adsorption phase. Little desorption was observed and constant solution phase concentrations were reached between 24h and 120h. The adsorption coefficients were calculated after 48h of adsorption, whereas desorption coefficients were calculated after 120h of desorption.

Kd values for BHT were between 201 (soil I) and >51000 (soil II) L/kg (log Kd between 2.3 and >4.7, respectively), for the sediment sample the Kd value was 152 L/kg (log Kd 2.2).

The calculated adsorption and desorption distribution coefficients were independent of the organic carbon content. Therefore, any environmental fate assessment should preferably be based on Kd_ads or Kd_des values.

The study used as source investigated Reaction mass of 7-azatridecane-1,13-diamine and hexamethylenediamine (EC 907 -605 -7, which contains relevant amounts of the submission substance,

7-azatridecane-1,13-diamine). The study results of the source compound were considered applicable to the target compound. Justification and applicability of the read-across approach (structural analogue) is outlined in the read-across report in section 13 or find a link in cross reference “assessment report”.

Description of key information

The adsorption/desorption behaviour of BHT amine containing the main constituents BHT (64.8%) and HMD (13.8%)

was investigated using four soil types covering a range of different soil properties: Speyer 2.1 (soil I, sand), Speyer 6S (soil II, clay), Empingham (soil III, clay loam), Mechtildshausen (soil IV, loam) and sediment of the River Rhine (soil V, sandy loam). Sorption of BHT to the investigated soils was strong but showed a dependency on the soil involved and on the soil-to-solution ratio used. Sorption was strongest to the clay soil (soil II) and weakest to the sand soil (soil I). With the exception of the river sediment (Soil V), sorption increased with increasing clay content. No correlation of sorption and the soil properties pH value, cation exchange capacity and organic carbon content was observed. The sorbed fraction of analyte increased with the amount of soil used in the batch systems. Apparent equilibrium distribution was reached within 48h. Desorption was investigated for 120h after the 48h adsorption phase. Little desorption was observed and constant solution phase concentrations were reached between 24h and 120h. The adsorption coefficients were calculated after 48h of adsorption, whereas desorption coefficients were calculated after 120h of desorption.

Kd values for BHT were between 201 (soil I) and >51000 (soil II) L/kg (log Kd between 2.3 and >4.7, respectively), for the sediment sample the Kd value was 152 L/kg (log Kd 2.2).

The calculated adsorption and desorption distribution coefficients were independent of the organic carbon content. Therefore, any environmental fate assessment should preferably be based on Kd_ads or Kd_des values.

Key value for chemical safety assessment

Other adsorption coefficients

Type:

log Kp (solids-water in soil)

Value in L/kg:

4.281

at the temperature of:

20 °C

Other adsorption coefficients

Type:

log Kp (solids-water in sediment)

Value in L/kg:

4.57

at the temperature of:

20 °C

Other adsorption coefficients

Type:

log Kp (solids-water in suspended matter)

Value in L/kg:

4.57

at the temperature of:

20 °C

Additional information

For Kp (solids-water in soil), the arithmetic mean value over four soils was used (19112 L/kg).

For both, Kp (solids-water in sediment) as well as Kp (solids-water in suspended matter), the value derived from soil V (river Rhine sediment) was used (37132 L/kg).

No data are available for STP sludge adsorption.