Tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate

Henry's Law constant

Link to relevant study record(s)

Reference

Endpoint:

Henry's law constant

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Justification for type of information:

QSAR

Principles of method if other than guideline:

Estimation Program Interface (EPI) Suite v4.10: HENRYWIN (v3.20). The bond contribution method is used to calculate the volatility of the substance from the aqueous phase.
The Estimation Program Interface was developed by the US Environmental Agency's Office of Pollution Prevention and Toxics, and Syracuse Research Corporation (SRC). © 2000 - 2011 U.S. Environmental Protection Agency for EPI SuiteTM (Published online in January 2011).

GLP compliance:

no

H:

0 Pa m³/mol

Temp.:

25 °C

Remarks on result:

other: the reported value is 1.21E-21 Pa m³/mol

Validity of the model:

1. Defined Endpoint: Henry's Law Constant

2. Unambinguous algorithm: The bond method was chosen for this estimation instead of the group method because an independent evaluation of Altschuh et al. (1999) for a diverse set of organic chemicals found the bond method more accurate than the group method. For tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate the following descriptors were applied:

bond estimation method

class	bond contribution description	value
Hydrogen	6 Hydrogen to Carbon (aliphatic) Bonds	-0.7181
Hydrogen	1 Hydrogen to Oxygen Bonds	3.2318
Fragment	3 C-C	0.3489
Fragment	3 C-CO	5.1172
Fragment	3 CO-O	0.2143
Fragment	1 C-P	0.7786
Fragment	2 O-P	0.7861
Fragment	1 O=P	1.6334
Fragment	4 O-Na	12.9200

3. Applicability domain: With a molecular weight of 358.06 g/mole the substance is within the range of the training set (26.04 - 451.47 g/mole). Regarding the structure, the fragment descriptors used by the program for the estimation are complete.

4a. Statistical characteristics (bond method):

number in dataset: 442

correlation coeff. (r²): 0.977

standard deviation: 0.4

average deviation: 0.249 [all statistical data related to the LWAPC value]

Tetrasodium hydrogen 2-phosphonatobutane-1, 2, 4-tricarboxylate has more instances of C-CO and CO-O bonds than the maximum for all training set and a higher uncertainty can be expected.

4b. Statistical characteristics (group method):

number in dataset: 318

correlation coeff. (r²): 0.956

standard deviation: 0.397

average deviation: 0.223 [all statistical data related to the LWAPC value]

5. Mechanistic interpretation:

The Henry's law constant is an important factor in determining the environmental fate of chemicals. Indeed, this constant is a fundamental input for fugacity models that estimate the multimedia partitioning of chemicals.

This model is based on the calculation of respective descriptor values, with the help of experimentally derived HLC's for defined groups that comprise a compound. For modelling each compound is then split into its subgroups and the respective values are summed up to yield the HLC.

Adequacy of prediction:

The result for tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate falls within the applicability domain described above and the estimation rules applied for the substance appears appropriate. Therefore the predicted value can be considered reliable yielding a useful result for further assessment. It is indicated by the program, that if the estimated value for the HLC is less than 0.0304 Pa m3/mole the substance is considered essentially non-volatile from water. Therefore, the substance is expected to be non-volatile from water.

Conclusions:

The QSAR determination of the Henry's Law Constant for tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate using the model HENRYWIN included in the Estimation Program Interface (EPI) Suite v4.10 revealed a value of 1.21E-21 Pa*m³/mol at 25°C.

Executive summary:

The Henry's Law Constant (HLC) for tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate was predicted using the QSAR calculation of the Estimation Program Interface (EPI) Suite v4.10. Based on the Bond contribution methodology the

HLC was estimated to be 1.21E-21 Pa*m³/mol.

Description of key information

The QSAR determination of the Henry's Law Constant for tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate using the model HENRYWIN included in the Estimation Program Interface (EPI) Suite v4.10 revealed a value of 1.21E-21 Pa*m³/mol at 25°C, based on the Bond contribution methodology.

Key value for chemical safety assessment

Henry's law constant (H) (in Pa m³/mol):

0

at the temperature of:

25 °C

Additional information

With a estimated HLC of 1.21E-21 Pa*m³/mol the substance is considered essentially non-volatile from water.