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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
July 1978 - February 1979
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP, not conducted according to recognised guideline, but fully detailed method and results. Various phosphate esters assessed.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Method for the determiniation of the Octanol-Water Partition Coefficients was taken from the publication "Analytical Scheme for the Determination of the Octanol-Water Partition Coefficients of Some Aryl Phosphates" as listed in the references below.

References:
- Federal Register, 44, 16254 March 16, 1979
- Federal Register, 40, 28199 June 25, 1975
- To T. Cascieri from P.H. Weinew, C.J. Clark and W.W. Poinsett, "Analytical Scheme for the Determination of the Octanol-Water Partition Coefficients of Some Aryl Phosphates", January 16, 1979
- To J.F. Jadlocki from P,B. Weiner, C.J. Clark and W.W. Poinsett, "Interim Progress Report on the Determination of the Octaaol-Water Partition Coefficient of K200B and Pydraul 50E1', February 22, 1979
- Saeger, V,W. ec ale, "Environmental Fate of Selected Phosphate Esters, Environmental Science and Technology, 2, 840 (1979) Howard, P .He and Deo, P .Go, "Degradation of Aryl Phosphates in Aquatic Environmenrs", Bulletin of Environmental Contamination and Toxicology, 22, 337 (1979)
- To T. Cascieri from P.H. Weiner, C.J. Clark and W.W. Poinsett, "Determination of the Octanol-Water Partition Coefficient of Tricresyl phosphate", November 22, 1978
- To T. Cascieri from P.H. Weiner, C.J. Clark and W.W. Poinsett, "Determination of the Octanol-Water Particion Coefficient of Trixylyl Phosphate", November 22, 1978
- To T. Cascieri from P.H. Weiner, C.J. Clark and W.W. Poinsett, "Interim Progress Report on the Determination of the Octanol-Water Partition Coefficients of Some Triaryl Phosphates",October 18, 1978
- To J.F. Jadlocki from P.H. Weiner, F. Schweder, W.W. Poinsett and C.J. Nicholson, "Determination of the Octanol-Water Partition Coefficient of Triphenyl Phosphate (TPP)", April 3, 1979
- To J.F. Jadlocki from P.H. Weiner, C.J. Clark, W.W. Poinsett and C.J. Nicholson, "Determination of the Octanol-Water Partition Coefficient of TBP', March 9, 1979
- To J.F. Jadlocki from P.H. Weiner, C.J. Clark, W.W. Poinsett and C.J. Nicholson, "Determination of the Octanol-Water Partition Coefficient of KP1401', February 27, 1979
GLP compliance:
not specified
Type of method:
other: Gas Chromatographic Analysis
Partition coefficient type:
octanol-water
Analytical method:
gas chromatography
Type:
Pow
Partition coefficient:
85 000 - 150 000
Remarks on result:
other: pH and temperature were not recorded within the report.
Type:
log Pow
Partition coefficient:
4.92 - 5.17
Remarks on result:
other: pH and temperature were not recorded within the report.
Details on results:
It should be noted that although these coefficients indicate a moderate potential for the esters to concentrate, their levels are one to two orders of magnitude less than those reported for some pesticides and PCBs. In addition, the potential for these esters to actually bioaccumulate to significant levels in the environment is a function of many factors. Chief among these factors is exposure: the materials must have the opportunity for broad exposure to aquatic communities during their manufacture, distribution, use or disposal. Additionally, i f a material enters the aquatic environment during its lifetime , there is a possibility that it will decompose before it has the opportunity t o bioconcentrate. The mobility of a material in aquatic and soil systems must also be considered, as if the material is readily adsorbed to soils or sediments, for example, it will be less likely to wash into lakes and streams and to be transported once there.

Since phosphate esters are widely distributed and have a potential for entering aquatic environments, it is recommended that these products be managed to prevent their entrance to natural aquatic environments. Information available in the literature indicates that these phosphate esters biodegrade and, therefore, may be removed through conventional biological wastewater treatment. This is just one approach to preventing these products from entering natural aquatic environments.

The highest partition coefficients were observed in the naturally derived triaryl phosphates, tricresyl phosphate (Kronitex TCP) and trixylenyl phosphate (Kronitex TXP ). The synthetic triaryl phosphates, Kronitex 100, Kronitex 200B, Kronitex 200 and Kronitex 50, all had partition coefficients lower than the natural triaryl phosphates. The non-substituted triaryl phosphate triphenyl phosphate (TPP) had the lowest partition coefficient of the triaryl phosphates. Note that TPP was synthesized for experimental use and is not a commercial product, however, it is a major component of several commercial triaryl phosphates. The alkyl phosphate esters, tributyl

phosphate (Kronitex TBP) and tributoxyethyl phosphate (Kronitex KP140) had the lowest partition coefficient of all the products tested. The octanol-water partition coefficients of the phosphate esters tested, ranged from 6.38 x l0^3 to 8.60 x l0^5 . With partition coefficients of this magnitude, each of these phosphate esters has the potential to bioaccumulate.

Table 1: Octanol-Water Partition Coefficients of Kronitex Phosphate Esters:

 Kronitex Phosphate Ester

Partition Coefficient 

Tricresyl Phosphate (Kronitex TCP) 

(8.6 +/- 4) x 10^5 

Trixylenyl Phosphate (Kronitex TXP) 

(5.1 +/- 0.3) x 10^5 

 Synthetic Isopropylphenyl Phosphate (Kronitex100)

(1.5 +/- 0.1) x 10^5

 tert-Butylphenyl Phosphate (Kronitex 200B)

(1.27 +/- 0.4) x 10^5

 Synthetic Isopropylphenyl Phosphate (Kronitex 200)

(1.20 +/- 0.3) x 10^5 

 Synthetic Isopropylphenyl Phosphate (Kronitex 50)

(8.5 +/- 1.5) x 10^4 

 Triphenyl Phosphate (TPP)

(4.6 +/- 0.7) x 10^4 

 Tributyl Phosphate (Kronitex TBP)

(1.02 +/- 0.08) x 10^4

 Tributoxyethyl Phosphate (Kronitex KP140)

(6.38 +/- 0.56) x 10^3

Conclusions:
The partition coefficient is reported as a range based on the values obtained for Kronitex 50, Kronitex 100 and Kronitex 200, all of which are indicative of the substance itself. This equates to a log Pow value of 4.92 to 5.17. This value is indicative of the propensity of the substance to bioaccumulate.
Executive summary:

The partition coefficient is reported as a range based on the values obtained for Kronitex 50, Kronitex 100 and Kronitex 200, all of which are indicative of the substance itself. This equates to a log Pow value of 4.92 to 5.17. This value is indicative of the propensity of the substance to bioaccumulate.

Description of key information

Partition coefficient

Key value for chemical safety assessment

Log Kow (Log Pow):
4.92
at the temperature of:
25 °C

Additional information

A single GLP compliant gives the partition coefficient as a range of Log Pow 4.92 – 5.17.