N-(2-{[C16-18 (even numbered) alkanoyl]amino}ethyl)-N-(2-hydroxyethyl)[C16-18 (even numbered) alkylamide

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 July 2017 - 01 June 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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:

EU Method A.8 (Partition Coefficient - HPLC Method)

Version / remarks:

Regulation (EC) 440/2008 of 30 May 2008

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Version / remarks:

April 2004

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

other: N/A - Partition coefficient determined by HPLC method.

Key result

Type:

log Pow

Partition coefficient:

> 6.5

Temp.:

30 °C

pH:

ca. 7

Remarks on result:

other: Limit value

Evaluation of Data:

The capacity factor for each reference standard was calculated using Equation 1 & Equation 2:

 

Equation 1:

k’ = (t_r– t₀)/t₀

 

Where:

k'        =         capacity factor
t_r         =         retention time (min)
t₀        =         dead time retention time (min)

 

Construction of the Calibration Curve

A correlation of log k' versus log₁₀P_owof the reference standards was plotted using linear regression. The capacity factors (k') for the reference standards were calculated using Equation 1. The log₁₀P_owvalues are those quoted in Method 117 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

 

 

Partition coefficient

Initially, the capacity factor of the test item was calculated using Equation 1. The partition coefficient was then calculated using Equation 2 with reference to the calibration curve.

 

Equation 2:

Log₁₀P_ow= (Log₁₀k’ – A)/B

 

Where:

P_ow      =         partition coefficient

k'        =         capacity factor

A         =         intercept of the calibration curve

B         =         slope of the calibration curve

 

 

Results – Preliminary Test:

The log₁₀ Pow was estimated to be 7.85.

 

 

Results – Calibration:

The retention times of thiourea (dead time determination) and the retention times, capacity factors (k') and log₁₀P_owvalues for the reference standards are shown in Table 3 and Table 4.

 

Table 3:          Retention Data for Thiourea

Dead Time	Retention Time (mins)		Mean Retention Time (mins)
	Injection 1	Injection 2
Thiourea	1.361	1.361	1.361

 

 

Table 4:          Retention Data for Reference Standards

Standard	Retention Time (mins)			Capacity Factor (k')	Log10k'	Log10Pow
	Injection 1	Injection 2	Mean
2-Butanone	1.487	1.497	1.492	0.096	-1.02	0.3
Benzene	2.012	2.026	2.019	0.484	-0.315	2.1
Naphthalene	2.779	2.799	2.789	1.05	2.12 x 10-2	3.6
Phenanthrene	4.417	4.466	4.441	2.26	3.55	4.5
Triphenylamine	9.558	9.704	9.631	6.08	7.84	5.7
DDT	12.191	12.396	12.293	8.04	9.05	6.5

Note: log₁₀P_owvalues are those reported in Method 117 of the OECD Guidelines for Testing of Chemicals, 13 April 2004

 

 

The calibration curve from which the sample results were taken yielded an equation of the line of: y = 0.3117x – 1.0568. The R²-value = 0.9921.

 

 

Results – Partition Coefficient of the Test Item:

The retention times, capacity factor and log₁₀P_owvalue determined for the test item are shown in Table 5.

 

Table 5:          Test Item Partition Coefficient

Peak	Injection	Retention Time (mins)	Capacity Factor (k')	Log10 k'	Log10 Pow	Mean Area %
Peak 1	1	8.387	5.16	0.713	5.68	4
	2	8.576	5.30	0.725	5.72
Peak 2	1	19.781	13.5	1.13	> 6.5	7
	2	19.854	13.6	1.13	> 6.5
Peak Group	1	> 60	Not Determined		> 6.5	89
	2	> 60	Not Determined		> 6.5

 

Overall result (main group, 89% by area normalization)

Log₁₀P_ow:                  > 6.5

Partition coefficient:  > 3.16 x 10⁶

 

 

The result from the preliminary estimate indicated that the HPLC method was suitable for determination of the partition coefficient.

 

As the test item does not contain any modes of dissociation within the environmentally relevant range, testing was performed at approximately neutral pH with the test item in a non-ionized form.

 

The main component group (> 60 min) in the chromatography was determined to be approximately 89% by area percentage normalization. This is consistent with the test item and as such, the partition coefficient of the main peak has been reported.

Conclusions:

The test item was determined to have a partition coefficient (Log Pow) of > 6.5 at a mean temperature of 30 °C.

Executive summary:

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

Following an initial estimation of the test item’s partition coefficient using KOWWIN v1.68, a main test was performed.  The test system consisted of a high-performance liquid chromatograph with an appropriate detector, a reverse phase HPLC column with a very low percentage of polar groups and a mobile phase of methanol and purified water (55:45 v/v).  Under these experimental conditions the column dead time and retention time of several guideline reference standards were determined.  These data were used to determine the capacity factor of each reference standard and construct a calibration curve.  The capacity factor of the test item was then sought by measuring its retention time under the described conditions, the test item was twice injected into the HPLC and a mean retention time determined.

For the test item a measured partition coefficient of log Pow > 6.5 was determined.  The main component group in the chromatography was determined to be approximately 89 % by area percentage normalisation.  This is consistent with the test item composition and as such, the partition coefficient of the main peak has been used to determine the Log Pow value.  At a retention time of > 60 min, this peak was retained for a significantly longer time than that of the reference standard with the longest retention time.  As such a limit value has been reported.

Description of key information

Partition coefficient: Log Pow: > 6.5 at 30.0°C; EU Method A.8. (HPLC Method); R. Butler (2018)

Additional information

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

Following an initial estimation of the test item’s partition coefficient using KOWWIN v1.68, a main test was performed.  The test system consisted of a high-performance liquid chromatograph with an appropriate detector, a reverse phase HPLC column with a very low percentage of polar groups and a mobile phase of methanol and purified water (55:45 v/v).  Under these experimental conditions the column dead time and retention time of several guideline reference standards were determined.  These data were used to determine the capacity factor of each reference standard and construct a calibration curve.  The capacity factor of the test item was then sought by measuring its retention time under the described conditions, the test item was twice injected into the HPLC and a mean retention time determined.

For the test item a measured partition coefficient of log Pow > 6.5 was determined.  The main component group in the chromatography was determined to be approximately 89 % by area percentage normalisation.  This is consistent with the test item composition and as such, the partition coefficient of the main peak has been used to determine the Log Pow value.  At a retention time of > 60 min, this peak was retained for a significantly longer time than that of the reference standard with the longest retention time.  As such a limit value has been reported.