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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Publication meets basic scientific principles, limited documentation
Reference:
Composition 1
Qualifier:
no guideline followed
Principles of method if other than guideline:
The octanol-water partitioning coefficent was determined following the principles of the shake-flask method of OECD TG 107. Test material was shaken with an octanol water mixture, phases were separated by centrifugation and analysed for test substance concentration by GLC.
GLP compliance:
no
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water
Test material information:
Composition 1
Analytical method:
gas chromatography
Type:
log Pow
Partition coefficient:
5.2
Remarks on result:
other: no temp. specified
Conclusions:
The log Kow of isopropylbiphenyl (mixture of isomers) was determined to be 5.20 using the shake flask method and GC analysis of the compound concentrations in the two phases.
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well-documented study report which meets basic scientific principles, pre-guideline study, but similar to OECD TG 117
Reason / purpose:
reference to same study
Reference:
Composition 1
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
yes
Remarks:
; retention times not capacity factors used for evaluation, water content of eluent < 25%, only single determinations
Principles of method if other than guideline:
Pre-guideline test. The method used was essentially that of Veith GD et al (Water Research 1979, 13, pp. 43-47). This method is similat to OECD TG 117 with some deviations. Reference compounds used are mostly listed in TG 117.
GLP compliance:
no
Remarks:
pre-GLP study
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Test material information:
Composition 1
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
5.33
Remarks on result:
other: ambient temp., isomer A
Type:
log Pow
Partition coefficient:
5.51
Remarks on result:
other: ambient temp., isomer B
Details on results:
Log Kow's of the standard compounds were plotted against the log retention time using a linear regression and a second order polynomial fit (Figure 5 of test report, see "Attached background material"). The latter fitted the data better as indicated by the statistics of both regression equations (Table IV of test report). Using the equation from the second order polynomial fit, log Kow values for the test substance were determined. For each of the two isomers of isopropylbiphenyl (IPB), a distinct log Kow value was obtained. Isomers could not be assigned as areas of the HPLC chromatogram were about equal.

Substance

Retention Time
(min)

Log RT

Log Kow

IPB isomere A

11.55

1.06

5.33

IPB isomere B

13.03

1.11

5.51

 

Conclusions:
Log Kow values of isopropylbiphenyl (mixture of two isomers) were examined in a pre-guideline study using an HPLC method similar to OECD TG 117 with some deviations (retention times not capacity factors used for evaluation, water content of eluent < 25%, only single determinations). The Log Kow values of the two isomers were determined to be 5.33 and 5.51.
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
disregarded due to major methodological deficiencies
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: Adequately-documented study report which meets basic scientific principles; but serious deviations from test guidelines
Reason / purpose:
reference to same study
Reference:
Composition 1
Qualifier:
no guideline followed
Principles of method if other than guideline:
The method used resembles OECD TG 107 but shows some restrictions.
Generel procedure:
Test material, dissolved in n-octanol, is shaken with an excess of water for 15 min. Then, water samples are centrifuged and extracted with hexane. After concentration of hexane, the content of test substance is measured by GC analysis.
GLP compliance:
no
Remarks:
pre-GLP study
Type of method:
shake-flask method to: flask method
Remarks:
pre-guideline study
Partition coefficient type:
octanol-water
Test material information:
Composition 1
Analytical method:
gas chromatography
Type:
log Pow
Partition coefficient:
7
Remarks on result:
other: temperature and pH not specified
Conclusions:
Compared to current guidelines, the method used has substantial shortcomings. Four parallel experiments were set up. But the hexane extracts seem to have been interspersed. One same experiment was not performed in duplicate. There was no change in conditions between experiments (three different volume ratios, amount of test substance if indicated). Concentration of test substance was analysed only in the aqueous phase but not in the n-octanol phase. The two solvents were not mutually saturated before determination of the partition coefficient. Temperature was not strictly controlled.
Endpoint:
partition coefficient
Type of information:
calculation (if not (Q)SAR)
Remarks:
Migrated phrase: estimated by calculation
Adequacy of study:
weight of evidence
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 adequate and reliable documentation / justification
Justification for type of information:
QSAR calculation
Reference:
Composition 1
Qualifier:
no guideline followed
Principles of method if other than guideline:
Q)SAR calculation with calculation program US EPA EPI Suite v4.11, program component KOWWIN (v1.68); molecular structure is divided into fragments and log Kow is estimated by summing together coefficients for each fragment (AFC method; US EPA 2012. Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.11; United States Environmental Protection Agency, Washington, DC, US).
Type of method:
other: calculation
Partition coefficient type:
octanol-water
Test material information:
Composition 1
Type:
log Pow
Partition coefficient:
5.21
Remarks on result:
other: value calculated

Description of key information

Log Kow of (1-methylethyl)-1,1'-biphenyl was determined in a pre-guideline study using a HPLC method similar to OECD TG 117. Similar results were obtained in a study following the principles of OECD TG 107 (Shake Flask Method).

Key value for chemical safety assessment

Log Kow (Log Pow):
5.33
at the temperature of:
20 °C

Additional information

Log Kow of (1-methylethyl)-1,1'-biphenyl was determined in three independent experimental studies (Mendoza/Dow 1981 - HPLC method, Addison 1983 - shake flask method, Ozburn et al 1980 - shake flask method). Results of the first two studies were close together (5.33/5.51 - two different isomers and 5.2, respectively). Log Kow of the Ozburn study was 7. This study was disregarded as experimental conditions were rather deviant from guideline requirements and the result was two orders of magnitude higher than the values of the other two studies. With the estimation program KOCWIN v1.83 within US EPA EPISuite v4.11, a log Kow of 5.21 was calculated that is in good agreement with the experimental values. A log Kow of 5.33 was selected to characterise the substance as this value represents the mean.