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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption to solid phase is expected.  

Key value for chemical safety assessment

Additional information

The Pigment Orasol Black X51 (EC no. 939-191-9) is a multipartite chromium complex composed of single complex fractions of azo compounds and amine compounds of the mixture Tridecanamine (TDA), branched and linear (CAS 86089-17-0).

 

TDA, branched and linear (CAS 86089-17-0) is a mixture of (predominantly) mono-alkyl amines with varying alkyl-chain length in a range between C10 and C14. The main fraction consists of C13 amines followed by the C12- , C11- and C14-amines. The following relative distribution of the C10 to C14 alkylamines was confirmed by GC/MS analysis:

•      C10-amines: 1% (selected as representative amine compound; reason: shortest alkyl chain)

•      C11-amines: 12%

•      C12-amines: 16%

•      C13-amines: 68% (selected as representative amine compound; reason: main component)

•      C14-amines: 3% (selected as representative amine compound; reason: longest alkyl chain)

 

EPI SuiteTM cannot be used for all chemical substances. The intended application domain is organic chemicals. Inorganic and organometallic chemicals generally are outside the domain. Therefore, there are no reliable estimated data for the organometallic component Orasol Black X51 (EC no. 939-191-9) available.

As EPI Suite is not capable of reliably estimating data for Orasol Black X51, the calculation was also performed for the respective azo-dye components without metal complexation (CAS 6434-57-7 and CAS 14847-54-2) as well as for three representative amine compounds (C10, C13 and C14).

 

KOCWIN v2.00 (EPI Suite v4.11) calculation results for Orasol Black X51 (EC no. 939-191-9) as well as the selected representative azo- and amine components:

Substance

MCI method

Log Kow method

In applicability domain?

KOC

[L/kg]

Log KOC

[dimensionless]

KOC

[L/kg]

Log KOC

[dimensionless]

Orasol Black X51

(EC no. 939-191-9)

complete complex

Log Kow = 3.1*

1.0E+10

10.17

2875

3.46

No

Orasol Black X51

(EC no. 939-191-9)

complete complex

Log Kow = 3.8*

7012

3.85

No

Azo-component

(CAS 6434-57-7)

1.084E+05

5.04

1.968E+05

5.29

No

Azo-component

(CAS 14847-54-2)

C10-Amine component 

(CAS 2016-57-1)

1620

3.21

987

2.99

Yes

C13-Amine component

(CAS 2869-34-3)

9805

3.99

6416

3.81

Yes

C14-Amine component

(CAS 2016-42-4)

17870

4.25

12130

4.08

Yes

*Study report: BASF SE (2016); report no.: 16L00106

 

The complete complex Orasol Black X51 is a Quaternary Ammonium Compound (QAC). Adsorption of QACs seem to occur mainly by an ion-exchange mechanism and depends on cation-exchange capacity of the sorbent and variety of other parameters (Boethling, 1994). The training set for the Koc estimation of this program did not include any QACs. Therefore, the Koc estimate is outside the program's prediction domain. In addition, the molecular weight is outside of the range of the training and validation set of the model; therefore, the estimate may be less accurate.

As key values for the chemical safety assessment, the results of the log Kow method were selected, as the log Kow method of KOCWIN v2.00 estimates the KOC based on the available measured substance’s n-octanol/water partition coefficient. Furthermore, the values calculated for the representative single components support the values calculated with the log Kow method.

These estimates refer to uncharged molecules.

 

In addition, pH-corrected KOC values for the charged molecule could be calculated for the representative amine components of Orasol Black X51 based on the available data on log Kow and pKa of these substances. At environmentally relevant conditions, the selected representative amine components (C10: Decylamine, CAS# 2016-57-1; C13: Tridecylamine, CAS# 2869-34-3; C14: Tetradecylamine, CAS# 2016-42-4) will be present in ionized form (pKa = 10.41 for each component, acc. to SPARC on-line calculator). Therefore, the adsorption coefficient was calculated according to Franco & Trapp (2008, 2009, 2010) to correct for the charged molecule at pH 5, 7, and 8. This pH range is representative for 98% of the European soils. The model is not yet validated; in addition, the applicability domain is not clearly defined. Nevertheless, the Koc values of the Franco & Trapp method give a good indication on the adsorption potential of a substance depending on the pH conditions of soil. The method is based on the dissociation constant pKa and the log Kow for the uncharged molecule. Estimated Kow values (calculated for charged molecule with EPI Suite v4.11) were used for this estimation.

 

Resulting Koc values of the selected representative amine components at pH 5-8 according to Franco & Trapp (2008/2009/2010):

Substance

KOC

pH 5 – pH 8

[L/kg]

Log KOC

pH 5 – pH 8

[dimensionless]

C10-Amine component

(CAS 2016-57-1)

28270 - 28166

4.45

C13-Amine component

(CAS 2869-34-3)

38014 - 37884

4.58

C14-Amine component

(CAS 2016-42-4)

38320 - 38197

4.58

Estimates referring to the charged molecule.

 

Overall conclusion:

By a weight-of-evidence approach based on the available estimated data for Orasol Black X51 and selected relevant components, it can be concluded that adsorption to the solid soil phase is expected under environmentally relevant conditions. As key value for the chemical safety assessment of the complete complex Orasol Black X51, the calculated value for the complete complex Orasol Black X51 (log Kow = 3.8, according to BASF SE, 2016 rep. no. 16L00106) was selected, considering a worst-case approach.

 

QSAR-disclaimer

In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met.

According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.

For the assessment of the Orasol Black X51 (EC no. 939-191-9) (Q)SAR results were used for the estimation of the adsorption potential. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.

Therefore, further experimental studies on the adsorption potential are not provided.

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