N-(2-hydroxyethyl)dodecanamide

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 August 2017 - TBC

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Remarks:

Study was conducted in accordance with international guidelines and in accordance with GLP. All guideline validity criteria were met.

Qualifier:

according to guideline

Guideline:

other: EU Method A.8. (Partition Coefficient - Estimation Method (Solubility Ratio))

Version / remarks:

Regulation (EC) 440/2008 of 30 May 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

estimation method (solubility ratio)

Partition coefficient type:

octanol-water

Analytical method:

gas chromatography

mass spectrometry

Key result

Type:

log Pow

Partition coefficient:

3.8

Temp.:

20 °C

Remarks on result:

other: pH not determined

Evaluation of Data:

The mean peak total area and concentration of each standard were plotted on a calibration curve and the sample concentration interpolated from the curve. The concentration was then corrected for dilution factor (50, 200).

The partition coefficient was calculated using Equation 1.

 

Equation 1:

P_ow= C_org/C_aq

 

Where:

P_ow      =         partition coefficient
C_org     =         n-octanol solubility (g/L)
C_aq      =         water solubility (1.14 x 10^-2g/L)

 

 

Results – Preliminary Test:

The preliminary estimate by visual assessment of the n-octanol solubility was in the range of approximately 2 to 5 g/L.

 

 

Results – Definitive Test:

The mean peak areas relating to the standard and sample solutions are shown in Table 2.

 

Table 2:          Mean GC-MS Peak Areas, Standard and Sample Solutions

Solution	Mean peak area
Standard 100 mg/L	8.401 x 10^4
Standard 250 mg/L	3.463 x 10^5
Standard 500 mg/L	1.164 x 10^6
Standard 517 mg/L	1.356 x 10^6
Standard 1000 mg/L	3.116 x 10^6
Standard 1500 mg/L	5.692 x 10^6
Sample 4A	5.192 x 10^6
Sample 4B	5.570 x 10^6
Sample 4C	6.767 x 10^5
Sample 4D	6.758 x 10^5
Sample 5A	4.726 x 10^6
Sample 5B	4.981 x 10^6
Sample 5C	6.797 x 10^5
Sample 5D	5.966 x 10^5
Sample 6A	6.405 x 10^6
Sample 6B	6.621 x 10^6
Sample 6C	8.087 x 10^5
Sample 6D	8.137 x 10^5

 

 

The concentration (g/L) of test item in the sample solutions is shown in Table 3.

 

Table 3:          Test Item Sample Solutions

Sample number	Time shaken at ~ 30°C (hours)	Concentration (g/L)	Mean concentration (g/L)
4A	96	70.6	69.5
4B	96	74.0
4C	96	66.7
4D	96	66.7
5A	120	66.2	65.7
5B	120	68.6
5C	120	66.9
5D	120	61.2
6A	144	81.2	78.9
6B	144	83.0
6C	144	75.6
6D	144	75.9

 

Mean concentration: 71.4 g/L at 20.0 ± 0.5°C

 

 

Partition Coefficient:

From the respective solubilities of the test item in water (see Section 4.5) and n-octanol, the partition coefficient of the test item was calculated to be 6.28 x 10³, log₁₀Pow 3.80.

 

 

Discussion:

Based on the preliminary result by visual assessment, three separate mixtures (Samples 1, 2 and 3) of test item and n-octanol were prepared at a loading rate of 25 g/L. The samples were shaken (100 rpm) at 30.0 °C for the 25¾, 49 and 72¼ hours at 30°C followed by static equilibration at 20.0 °C for a period of 24½ hours. Observations of the saturated solutions indicated that the majority of the test item had dissolved after shaking for 72 hours. The solutions were centrifuged at 13000 rpm for 15 min and analysed. The response for the samples solutions were outside the calibration standard range. Therefore, further testing was performed a greater loading rate to provide saturated solutions. The loading rate was increased to 200 g/L and the shaking time was extended to 96, 120 and 144 hours. This higher loading rate and extended shaking time has been reported as the definitive test.

 

On completion of the equilibration period, the samples were observed to be white viscous pastes. After centrifuging and filtering the solutions were clear pale-yellow solutions with a visible Tyndall beam. 

Conclusions:

From the respective solubilities of the test item in water and n-octanol, the partition coefficient of the test item was calculated to be 6.28 x 10^3, log10 Pow 3.80.

Executive summary:

EU Method A.8.  – The partition coefficient of the test item was determined using the estimation method (Solubility Ratio)).  The procedures employed were designed to be compatible with Method A.8., partition coefficient, of Commission Regulation (EC) No 440/2008 of 30 May 2008.

Following a preliminary test aliquots of test item (10.0 g) were added to three separate flasks containing n-octanol (50 ml each).  Each vessel was shaken at elevated temperature (100 rpm at 30.0 ± 1.0 °C) for 96, 120 and 144 hours respectively.  After shaking, each vessel was subject to static equilibration (20.0 ± 0.5 °C) 24 hours.  The solutions were centrifuged at 13,000 rpm for 15 minutes, checked for colloidal matter and analysed.  The concentration of test item in the sample solutions was determined by gas chromatography with mass spec detection (GC-MS).

On completion of the equilibration period, the samples were observed to be white viscous pastes.  After centrifuging and filtering the solutions were clear pale-yellow solutions with a visible Tyndall beam.

For the test item an estimated partition coefficient of log10 Pow 3.80 was determined.

Description of key information

Partition coefficient: Log Pow = 3.8 at 20.0°C; EU Method A.8. (Estimation Method (Solubility Ratio)); R. Butler (2018)

Key value for chemical safety assessment

Log Kow (Log Pow):

3.8

at the temperature of:

20 °C

Additional information

EU Method A.8.  – The partition coefficient of the test item was determined using the estimation method (Solubility Ratio)).  The procedures employed were designed to be compatible with Method A.8., partition coefficient, of Commission Regulation (EC) No 440/2008 of 30 May 2008.

Following a preliminary test aliquots of test item (10.0 g) were added to three separate flasks containing n-octanol (50 ml each).  Each vessel was shaken at elevated temperature (100 rpm at 30.0 ± 1.0 °C) for 96, 120 and 144 hours respectively.  After shaking, each vessel was subject to static equilibration (20.0 ± 0.5 °C) 24 hours.  The solutions were centrifuged at 13,000 rpm for 15 minutes, checked for colloidal matter and analysed.  The concentration of test item in the sample solutions was determined by gas chromatography with mass spec detection (GC-MS).

On completion of the equilibration period, the samples were observed to be white viscous pastes.  After centrifuging and filtering the solutions were clear pale-yellow solutions with a visible Tyndall beam.

For the test item an estimated partition coefficient of log10 Pow = 3.80 was determined.