2-ethylhexyl 3,5,5-trimethylhexanoate

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

July - September 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

other: Slow stirring method with ultra performance liquid chromatographic system with triple quadrupole mass-spectrometric detection (UPLC-MS/MS) in gradient mode

Partition coefficient type:

octanol-water

Analytical method:

other: reversed phase chromatography on an ultra performance liquid chromatographic system with triple quadrupole mass-spectrometric detection (UPLC-MS/MS) in gradient mode using an external standard

Key result

Type:

log Pow

Partition coefficient:

>= 7.14 - <= 7.19

Temp.:

25 °C

pH:

>= 5.84 - <= 5.89

Remarks on result:

other: logPow average was 7.164 as mean of triplicate measurements

Details on results:

The partition coefficient (n-octanol/water) (log Pow) of the test item was determined at test temperature of 25 ± 1 °C and at a pH value of 5.89 from three independent replicates with four sub-replicates to be 7.164 ± 0.003.

The analytical method on test item was validated with satisfactory results regarding linearity, limit of quantification, accuracy, precision and specificity. The analytical system gave linear response in the range of nominal 0.3 to 50 µg/L (10 concentrations; 7 concentrations in the range of 2 to 50 µg/L for the method validation of the n-octanol phase). The coefficients of determination (r²) were determined to be > 0.992 for all calibration curves used in this study.

The limit of quantification (LOQ) was set at nominal 1 µg/L with a dilution factor of 2, corresponding to a concentration of 0.5 µg/L in the final samples at 1 x LOQ, for the aqueous samples as well at nominal 0.4 g/L with a dilution factor of 100000, corresponding to a concentration of 4 µg/L in the final samples at 1 x LOQ, for the n-octanol samples and checked by means of accuracy.

Mean recovery rates (accuracy and precision) were:

- 105 % for the 1 x LOQ and 100 % for the 10 x LOQ of the aqueous samples and

- 108 % for the 1 x LOQ and 106 % for the 5 x LOQ of the n-octanol samples,

indicating sufficient accuracy of the analytical method. Furthermore, the precision of both fortification levels was satisfying because the corresponding coefficients of variation were = 7.1 %.

For specifying the signals detected on the qualifier ion trace confirmed the identity for all analysed samples above LOQ level. Response of blank values of control samples was significantly lower than 30 % of the LOQ.

Temperature measurements were in the range of 24.81 – 25.17 °C with mean values of 24.98, 24.92, and 24.98 °C in replicates 1, 2, and 3 respectively.

At test start, the pH-value of the aqueous phase, previously saturated with n-octanol, was determined before adding of the test item (ph = 5.843). The pH-values at test end were determined after the fourth sampling interval (pH = 5.887). The obtained results for the pH-values at test end match the pH-value at test start, it can be stated that the test item did not influence the pH-value of the aqueous phase.

The recovery rates of 100 - 110 % indicate sufficient stability of the test item in the n-octanol stock solution during the course of the study.

Regression analysis demonstrated that the slope of the regression line of the Pow of the four successive samples per replicate was not significantly different from zero.

Validity Criteria: The mean log Pow values in the equilibration time for each replicate did fall within a range of ± 0.3 log units. Temperatures were kept constant at 25 ± 1 °C for each determination of the partition coefficient.

Conclusions:

The partition coefficient (n-octanol/water) (log Pow) of test item was determined at test temperature of 25 ± 1 °C and at a pH value of 5.89 from three independent replicates with four sub-replicates to be 7.164 ± 0.003.

Executive summary:

The determination of the partition coefficient (n-octanol/water) of the test item was performed according to OECD 123 (2006) at DR. U. NOACK-Laboratories, 31157 Sarstedt, Germany.

The partition coefficient was determined employing the slow-stirring method at 25 ± 1 °C from three independent replicates with four sub-replicates. The pH-value of the aqueous phases was determined by a pH-meter.

Analytical evaluation was performed using UPLC-MS/MS on a reversed-phase column (C 18) in gradient mode using an external standard. The analytical method was validated prior to experimental starting with satisfactory results regarding linearity, limit of quantification, accuracy, precision and specificity.

The partition coefficient (n-octanol/water) (log Pow) of the test item was determined to be 7.164 ± 0.003 (at 25 ± 1 °C and at a pH of 5.89).

Reference 2

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2011-09-15

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The value is out of the domain of the method.

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

GLP compliance:

no

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

> 6

Temp.:

40 °C

pH:

7.71

Details on results:

The calculation value for logPow is 7.49. However, logP by HPLC method only valids for LogP values up to 6, therefore value reported as greater than 6.

Conclusions:

Partition coefficient: logPow > 6

Executive summary:

In a guideline test using HPLC method, the partition coefficient of the test substance was determined to be greater than 6.

Description of key information

log partition coefficient n-octanol/water: logPow 7.164 (25 °C, pH 5.89)

Key value for chemical safety assessment

Log Kow (Log Pow):

7.164

at the temperature of:

25 °C

Additional information

In a supporting study according to HPLC method the partition coefficient of the test material has been determined to be greater than 6 (estimated at 7.7) at 25 °C, indicating the test substance is far more soluble in octanol than in water. As the result was outside the calibration range of the HPLC method another study applying the slow stirring method was conducted (key study) which showed the logPow to be 7.164 at 25 °C and pH of 5.89.