Amines, C12-14-alkyl, C6-10-alkyl phosphates

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

Log Koc of the test substance components were calculated using regression model equations for acid and base ionisable compounds. See below under 'methods' for applicability domain.

Principles of method if other than guideline:

The soil adsorption coefficient (Koc) values for the test substance components were estimated using the log Pow (Partition coefficient) correlation approach of the Log Koc regression models equations for acid and base ionisable compounds.

Specific details on test material used for the study:

Input data for the model: Representative SMILES of the individual constituents:
1) dodecylamine: CCCCCCCCCCCCN
2) hexyl dihydrogen phosphate: CCCCCCOP(=O)(O)O
3) dihexyl hydrogen phosphate: CCCCCCOP(=O)(O)OCCCCCC
4) 2-ethylhexyl hexyl phosphate: CCCCC(CC)COP(=O)(O)OCCCCCC
5) 2-ethylhexyl dihydrogen phosphate: CCCCC(CC)COP(=O)(O)O
6) bis(2-ethylhexyl) hydrogen phosphate: CCCCC(CC)COP(=O)(O)OCC(CC)CCCC
7) 2-ethylhexyl 8-methylnonyl phosphate: CCCCC(CC)COP(=O)(O)OCCCCCCCC(C)C
8) Phosphoric acid, isodecyl ester: CC(C)CCCCCCCOP(=O)(O)O

Key result

Type:

log Koc

Value:

ca. 3.38 dimensionless

Remarks on result:

other: Koc: 2398.83

Remarks:

pH 7

Results

Koc was calculated using range of regression equations, i.e., acid and base variety, ionisable coumpound specific.

Table 1: Koc based on regression models equations (acid and base Ionisable Compound)

Regression Models Used to Estimate Log Koc from Log Kow (Franco and Trapp 2008)
Acid based equation	Log Koc = Log [Ǿn*10^{0.54 log Pn + 1.11} +Ǿion*10^{0.11 log Pn + 1.54}
Base based equation	Log Koc = Log [Ǿn*10^{0.37 log Pn + 1.70} +Ǿion*10^{pKa^0.65*f^0.14}

Table 2: Results

Constituent name	SMILES	Pka (Source: Chemicalize)	Log Kow (Source: EPI Suite)	Koc (Log Koc)
				pH 4	pH 7	pH 9
dodecylamine	CCCCCCCCCCCCN	10.21	4.76	33695.76 (4.52)	33677.28 (4.52)	31890.66 (4.50)
hexyl dihydrogen phosphate	CCCCCCOP(=O)(O)O	1.81-6.83	1.74	54.33 (1.74)	88.55 (1.95)	111.71 (2.05)
dihexyl hydrogen phosphate	CCCCCCOP(=O)(O)OCCCCCC	1.94	4.25	122.96 (2.09)	101.74 (2.00)	101.74 (2.00)
2-ethylhexyl hexyl phosphate	CCCCC(CC)COP(=O)(O)OCCCCCC	1.94	5.16	194.76 (2.29)	128.12 (2.11)	128.12 (2.11)
2-ethylhexyl dihydrogen phosphate	CCCCC(CC)COP(=O)(O)O	1.83-6.86	2.65	70.11 (1.85)	230.74 (2.36)	345.55 (2.54)
bis(2-ethylhexyl) hydrogen phosphate	CCCCC(CC)COP(=O)(O)OCC(CC)CCCC	1.94	6.07	369.98 (2.57)	161.32 (2.21)	161.32 (2.21)
2-ethylhexyl 8-methylnonyl phosphate	CCCCC(CC)COP(=O)(O)OCCCCCCCC(C)C	1.94	7.05	915.39 (2.96)	206.78 (2.31)	206.78 (2.31)
Phosphoric acid, isodecyl ester	CC(C)CCCCCCCOP(=O)(O)O	1.81-6.83	3.63	95.45 (1.98)	735.26 (2.87)	1166.97 (3.06)

The calculated pKa of the different constituents of the test substance indicates that the phosphates will exist primarily as an anion, whereas the amines as cation in the environment (pH 4 to 9). The positively charged cations adsorb generally stronger to sediment and soils containing organic carbon and clay than their neutral counterparts, while anions are expected to adsorb to a lesser extent to soil, sediment.

Validity criteria fulfilled:

not applicable

Conclusions:

Using the Log Koc regression models equations (acid and base ionisable compounds) based on partition coefficient value, the estimated Koc for the components of the test substance were determined to be 31890.26-33695.76 (log Koc 4.50-4.52 ) and 54.33-1166.97 L/kg (log Koc 1.74-3.06) for amine (cation) and phosphates (anion), respectively.

Executive summary:

The soil adsorption coefficient (Koc) values for the components (amine and phosphates) of test substance, 'Amines, C12-14-alkyl, C6-10-alkyl phosphates', were determined using the well-known log Kow based log Koc regression model equations for acid and base ionisable compounds (Franco and Trapp, 2008). The log Koc was calculated from the equations using the log Kow values determined for the components (generated from EPISuite model with the help of SMILES), whereas a фn and фion values were taken from individual components dissociation graph predictions in Chemicalize web-based tool, using the SMILES. The estimated log Koc of the test substance was determined as weighted average of the log Koc of the individual constituent mol fractions and the value was determined to be 3.38. For phosphates, the range of Koc indicates low to moderate sorption to soil / sediment and moderate to slow migration potential to ground water. For amine, the range of Koc indicates strong sorption to soil / sediment and negligible migration to ground water (US EPA, 2012).

Key value for chemical safety assessment

Koc at 20 °C:

2 398.83

Additional information

The soil adsorption coefficient (Koc) values for the components (amine and phosphates) of test substance, 'Amines, C12-14-alkyl, C6-10-alkyl phosphates', were determined using the well-known log Kow based log Koc regression model equations for acid and base ionisable compounds (Franco and Trapp, 2008). The log Koc was calculated from the equations using the log Kow values determined for the components (generated from EPISuite model with the help of SMILES), whereas a фn and фion values were taken from individual components dissociation graph predictions in Chemicalize web-based tool, using the SMILES. The estimated log Koc of the test substance was determined as weighted average of the log Koc of theindividual constituent mol fractions and the value was determined to be 3.38. For phosphates, the range of Koc indicates low to moderate sorption to soil / sediment and moderate to slow migration potential to ground water. For amine, the range of Koc indicates strong sorption to soil / sediment and negligible migration to ground water (US EPA, 2012).