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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Experimental phase from 2014-09-19 to 2014-09-29
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The study was conducted according to an internationally recognised method, and under GLP. No deviation was reported. The test substance is considered to be adequately characterised. Therefore full validation applies.
Qualifier:
according to guideline
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. QA statement)
Remarks:
inspected on June 3 to 5, 2013 / signed on November 5, 2013
Type of method:
slow-stirring method
Partition coefficient type:
octanol-water
Analytical method:
gas chromatography
Type:
log Pow
Partition coefficient:
5.79
Temp.:
25 °C
pH:
5.85
Remarks on result:
other: isomer 1, (alpha.R,1R,6S)-
Type:
log Pow
Partition coefficient:
5.59
Temp.:
25 °C
pH:
5.85
Remarks on result:
other: isomer 2, [1a(S*),6b]- (9Cl)

Method Validation:

The analytical method on test substance was validated with satisfactory results regarding linearity, limit of quantification, accuracy, precision and specificity.

 

Table 4.7/1: Partition coefficient – results (Isomer1)

Replicate

Test

Measured concentration

Pow

Log Pow

number

duration [h]

in n-octanol
[mg/L]

in aq. Phase
[mg/L]

 

Single

Mean

SD ±

CV

1

  91.34

5920

0.00852

694836

5.84

5.76

0.07

1.19

  96.52

5420

0.00964

562241

5.75

115.63

5280

0.00882

598639

5.78

120.64

4700

0.00990

474747

5.68

2

  91.34

6300

0.00816

772059

5.89

5.80

0.06

1.00

  96.52

5100

0.00892

571749

5.76

115.63

5640

0.00918

614379

5.79

120.64

5140

0.00860

597674

5.78

3

  91.34

6560

0.00848

773585

5.89

5.80

0.06

1.09

  96.52

4900

0.00802

610973

5.79

115.63

5340

0.00926

576674

5.76

120.64

5160

0.00916

563319

5.75

 

 

 

 

log POW,Av

  5.789

 

 

 

 

 

 

slog POW,Av

  0.007

 

 

 

Table 4.7/2: Partition coefficient – results (Isomer2)

Replicate

Test

Measured concentration

Pow

Log Pow

number

duration [h]

in n-octanol
[mg/L]

in aq. Phase
[mg/L]

 

Single

Mean

SD ±

CV

1

  91.34

12078

0.0318

380290

5.58

5.56

0.02

0.35

  96.52

10700

0.0308

347854

5.54

115.63

11612

0.0326

356634

5.55

120.64

11556

0.0304

379882

5.58

2

  91.34

12332

0.0302

408615

5.61

5.61

0.03

0.62

  96.52

11876

0.0269

441487

5.64

115.63

12478

0.0296

421554

5.62

120.64

11570

0.0316

365676

5.56

3

  91.34

12494

0.0289

432318

5.64

5.62

0.03

0.47

  96.52

12416

0.0280

442796

5.65

115.63

11580

0.0300

386515

5.59

120.64

11942

0.0291

410660

5.61

 

 

 

 

log POW,Av

  5.589

 

 

 

 

 

 

slog POW,Av

  0.042

 

 

 

Regression analysis demonstrated that the slope of the regression line of the log Pow of the four successive samples was not significantly different from zero.Therefore equilibrium was considered to be achieved.

The recovery rates for stock solution range between 68 and 92 %.

The mass balance for isomer 1 ranges between 69 – 96 %.

The mass balance for isomer 2 ranges between 79 – 92 %.

Conclusions:
The test substance has potential to bioaccumulate in the environment, according to CLP classification criteria for aquatic chronic toxicity (log Kow > 4).
Executive summary:

The partition coefficient of the test substance was measured under GLP according to the OECD 123 guideline, slow stirring method.

The partition coefficient (n-octanol/water) (log Pow) was determined for the individual isomers of the test item at test temperature of 25 ± 1 °C and at a pH value of 5.85 from three independent replicates (test vessels) with 4 sub-replicates (samples).

Quantification was performed using validated GC-MS analytical method.

The partition coefficient was determined as:

log Pow = 5.789 ± 0.007 for isomer 1 Cyclohexanepropanol,2,2,6‑trimethyl‑a‑propyl‑, (alpha.R,1R,6S)‑and

log Pow = 5.589 ± 0.042 for isomer 2 Cyclohexanepropanol,2,2,6‑trimethyl‑a‑propyl‑, [1a(S*),6b]‑ (9Cl)

Endpoint:
partition coefficient
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Based on structural similarity (diastereoisomers), no high difference is anticipated between the constituents.
Moreover, in a supporting HPLC study conducted on the source substance (Firmenich 2008), a single peak was observed, showing no significant difference between the isomers.
Therefore the result of the study will be considered for the target substance.

Further information is included in IUCLID Section 13.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across: supporting information
Key result
Type:
log Pow
Partition coefficient:
5.79
Temp.:
25 °C
pH:
5.85
Conclusions:
(from analogue) The substance has potential to bioaccumulate in the environment, according to CLP classification criteria for aquatic chronic toxicity (log Kow > 4).
Executive summary:

The partition coefficient of the test substance was measured under GLP according to the OECD 123 guideline, slow stirring method.

The partition coefficient (n-octanol/water) (log Pow) was determined for the individual isomers of the test item at test temperature of 25 ± 1 °C and at a pH value of 5.85 from three independent replicates (test vessels) with 4 sub-replicates (samples).

Quantification was performed using validated GC-MS analytical method.

The partition coefficient was determined as:

log Pow = 5.789 ± 0.007 for isomer 1 Cyclohexanepropanol,2,2,6‑trimethyl‑a‑propyl‑, (alpha.R,1R,6S).

A similar logKow is anticipated for the second isomer of the target substance.

Description of key information

Isomers expected to range between ca 5.59 and 5.79 (from analogue).

The substance has potential for bioaccumulation; the data is relevant for classification in aquatic chronic toxicity hazard class according to Regulation (EC) No.1272/2008 (CLP) criteria (log Kow>4).

Key value for chemical safety assessment

Log Kow (Log Pow):
5.79
at the temperature of:
25 °C

Additional information

No data is available on the substance itself.

However, a fully reliable experimental study, conducted according to a recognized OECD/EC method and under GLP, is available on an analogue (stereoisomers). Based on structural similarity, minor difference is anticipated with the present dossier substance, the read-across is considered justified for a key study, and the higher result is retained as key data (both worst-case and isomer common between source and target substances).

Despite the substance was considered as surface-active (please refer to IUCLID section 4.10), in the tests conditions, no surface-active behaviour is supposed to affect the validity of the study.