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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
From November 20 to 29, 1996
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
GLP study following OECD guideline 117 with minor deviations: no data about purity % and pH during test; no certificate of analysis of the test substance
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
yes
Remarks:
no data about purity % and pH during test; no certificate of analysis of the test substance
Principles of method if other than guideline:
not applicable
GLP compliance:
yes
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
2.6
Temp.:
30 °C
Remarks on result:
other: pH not available
Details on results:
Reference substances: see table 1

Table 1: Partition Coefficient: Determination by reverse-phase HPLC

  

Reference substances

log Pow

tR1

tR2

tRm

k

log k

Thiourea

 

1.81

1.81

1.81

 

 

Aniline

0.9

2.65

2.66

2.65

0.465

-0.332

Methyl benzoate

2.1

3.77

3.78

3.78

1.085

0.036

Benzophenone

3.2

5.4

5.41

5.4

1.984

0.298

Naphthalene

3.6

6.39

6.41

6.4

2.533

0.404

1,2,4-Trichlorobenzene

4.2

9.96

9.98

9.97

4.508

0.654

n-Butylbenzene

4.6

12.39

12.41

12.4

5.848

0.767

Triphenylamine

5.7

20.85

20.9

20.88

10.531

1.022

tR1, tR2, tRm: retention times (1st injection, 2nd injection, average)

k = (tR/tO) -1: capacity factor;

tO: "dead time", i.e. retention time of thiourea = 1.81

Linear regression parameters: log Pow = a * log k + b

where;

r2 = 0.995

a = 3.474

b = 2.058

Terpineol pure:

log Pow = 2.6

tR1 = 4.418

tR2 = 4.422

tRm = 4.42

k = 1.441

log k = 0.159

Conclusions:
The partition coefficient (log Pow) of TERPINEOL was determined to be 2.6 at 30 °C.
Executive summary:

The partition coefficient of TERPINEOL was determined by Reverse Phase High Performance Liquid Chromatographic, according to OECD Guideline 117 and in compliance with GLP.

 

The partition coefficient (log Pow) of TERPINEOL was determined to be 2.6 at 30 °C.

Endpoint:
partition coefficient
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
Terpinolene is an impurity of multiconstituent substance TERPINEOL MULTICONSTITUENT. Data on terpinolene are used as worst case data, in comparison with the main constituents of TERPINEOL MULTICONSTITUENT.
Reason / purpose:
read-across source
Key result
Type:
log Pow
Partition coefficient:
4.29
Remarks on result:
other: falls inside the Applicability Domain of the model
Conclusions:
The log Pow value of terpinolene is 4.29.
Executive summary:

Partition coefficient (log Pow) of substance terpinolene (CAS# 586-62-9) was calculated with the model i-SAFERAT Toolbox, Multilinear v.1.1. Calculation was performed from the input SMILES of terpinolene. Terpinolene fells inside the Applicability Domain of the model.

Therefore, the log Pow value of terpinolene is 4.29 and terpinolene can be excluded as potential bioaccumulative.

Endpoint:
partition coefficient
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
Terpinolene is an impurity of multiconstituent substance TERPINEOL MULTICONSTITUENT. Data on terpinolene are used as worst case data, in comparison with the main constituents of TERPINEOL MULTICONSTITUENT.
Reason / purpose:
read-across source
Principles of method if other than guideline:
Not applicable
Type:
Pow
Partition coefficient:
29 790
Temp.:
25 °C
Remarks on result:
other: ± 250
Key result
Type:
log Pow
Partition coefficient:
4.474
Temp.:
25 °C
Remarks on result:
other: ± 0.004

none

Conclusions:
The partition coefficient, Pow (mol/mol), of terpinolene was measured to be 29790 ± 250 (log Pow = 4.47± 0.004) at 25 °C.
Executive summary:

A study was conducted to determine the partition coefficient of terpinolene using the shake-flask method (de Bruijn et al., 1989; Dewulf et al., 1999) similarly to OECD Guideline No. 107. The octanol phase with the test substance was thoroughly mixed with water to reach the partition equilibrium. After separation by centrifugation, the concentration of the test substance in the octanol phase was determined by gas chromatography and the partition coefficient was calculated.

The partition coefficient of terpinolene was measured to be 29790 ± 250 (log Pow = 4.47 ± 0.004) at 25 °C.

Endpoint:
partition coefficient
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
Terpinolene is an impurity of multiconstituent substance TERPINEOL MULTICONSTITUENT. Data on terpinolene are used as worst case data, in comparison with the main constituents of TERPINEOL MULTICONSTITUENT.
Reason / purpose:
read-across source
Key result
Type:
log Pow
Partition coefficient:
4.24
Temp.:
37 °C
pH:
7.2
Remarks on result:
other: standard error: 0.05
Details on results:
Experimental log Kow (RP-HPLC) = 4.24 (S.E.: 0.05) at 37 °C
Calculated log Kow = 4.36 (fragment method), 4.88 (atom /fragment contribution method) and 2.71 (atomistic method)

none

Conclusions:
The partition coefficient of terpinolene was determined to be: log Pow = 4.24 (S.E. = 0.05) at 37 °C. The calculated log Kow values of terpinolene were 4.36 (fragment method), 4.88 (atom /fragment contribution method) and 2.71 (atomistic method).
Executive summary:

A study was conducted to determine the partition coefficient of terpinolene by Reverse Phase High Performance Liquid Chromatographic method similarly to OECD Guideline No. 117.

 

The partition coefficient of terpinolene was determined to be: log Pow = 4.24 (S.E. = 0.05) at 37 °C.

The calculated log Pow values of terpinolene were 4.36 (fragment method), 4.88 (atom /fragment contribution method) and 2.71 (atomistic method).

Endpoint:
partition coefficient
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
Alpha-terpineol is one of the main constituents of multiconstituent substance TERPINEOL MULTICONSTITUENT. Therefore, data on alpha-terpineol can be used for extrapolation to TERPINEOL MULTICONSTITUENT.
Reason / purpose:
read-across source
Key result
Type:
log Pow
Partition coefficient:
2.65
Temp.:
25 °C
Remarks on result:
other: predicted value (SPARC)
Type:
log Pow
Partition coefficient:
2.98
Temp.:
23.5 °C
Remarks on result:
other: experimental value

none

Conclusions:
The predicted and experimental values of the partition coefficient (log Pow) of alpha-terpineol were 2.65 (at 25 °C) and 2.98 (at 23.5 ± 0.5 °C), respectively.
Executive summary:

A study performed by shake-flask method was conducted to determine the partition coefficient of alpha-terpineol (Karickhoff and Brown, 1979).

 

The predicted and experimental values of the partition coefficient (log Pow) of alpha-terpineol were 2.65 (at 25 °C) and 2.98 (at 23.5 ± 0.5 °C), respectively.

Description of key information

The partition coefficient was derived from literature and QSAR values of the main constituents and the main impurities of the substance.
The partition coefficient of terpineol multiconstituent is stated to be 2.78 at 20°C.

Key value for chemical safety assessment

Log Kow (Log Pow):
2.78
at the temperature of:
20 °C

Additional information

In a weight of evidence approach, literature data and QSAR values were gathered for the main constituents and the main impurities of terpineol multiconstituent representing at least 80% of the substance.

The composition of the substance was taken into account and log Kow of terpineol multiconstituent was derived using a ponderate mean based on constituent/impurity contribution. The result is used as key value for chemical assessment.

Constituent/Impurity  Distribution %*  log Kow  Constituent contribution**
 (-)-alpha-terpineol & (+)-alpha-terpineol  62  2.6  1.612
 gamma-terpineol  10  2.6  0.260
 trans-beta-terpineol and cis-beta-terpineol  5.1  2.6  0.1326
 terpinolene  9  4.33  0.3897
 terpineol multiconstituent  100    2.7808

* Sum of the five molecules considered as 100%

** Constituent contribution = predicted log Kow x % of the substance

** Several data were available for terpinolene; the value included in the above table is the arithmetic mean of the gathered values.

Another way to present the results is to list the relative presence of the chemical structures with a given log Kow range:

log Kow range

% of constituent/impurity

log Kow < 3

77.1

3 ≤ log Kow < 4.5

 9

4.5 ≤ log Kow < 6

-

6 ≤ log Kow < 8

-

8 ≤ log Kow

-