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Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 14 June 2012 to 29 August 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to internationally recognised guidelines, and under GLP. No deviation affected the quality of the study.

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

11-04-11

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

< 0.3

Temp.:

25 °C

pH:

2.4

Remarks on result:

other: log Pow of N-[2-(2-Oxoimidazolidin-1-yl)ethyl]methacrylamide

Type:

log Pow

Partition coefficient:

0.79

Temp.:

25 °C

pH:

2.4

Remarks on result:

other: log Pow of methacrylic acid

Reference items results:

The retention times which were recorded for the reference items and calculated capacity factors k are presented in the following table:

Compound	RT1	RT2	RT3	RT4	RT5	RT6	Retention Time Mean	Retention Time Standard Deviation	Retention Time Relative Standard Deviation	k
	min.	min.	min.	min.	min.	min.	min.	min.	%
Thio urea	1.447	1.447	1.440	1.447	1.447	1.447	1.446	0.003	0.198	0.0000
2-Butanone	1.900	1.900	1.900	1.900	1.900	1.900	1.900	0.000	0.000	0.3141
Benzylalcohol	2.287	2.287	2.287	2.287	2.287	2.287	2.287	0.000	0.000	0.5818
Acetophenone	2.793	2.793	2.793	2.793	2.793	2.793	2.793	0.000	0.000	0.9318
Nitrobenzene	3.360	3.360	3.360	3.367	3.367	3.367	3.364	0.004	0.114	1.3263
Benzene	4.807	4.807	4.807	4.807	4.807	4.807	4.807	0.000	0.000	2.3247
Toluene	7.573	7.573	7.573	7.580	7.580	7.587	7.578	0.006	0.075	4.2410

The values for log k and log Pow of the reference items are presented in the following table:

Compound	log k	log Pow
2-Butanone	-0.5029	0.30
Benzylalcohol	-0.2352	1.10
Acetophenone	-0.0307	1.70
Nitrobenzene	0.1227	1.90
Benzene	0.3664	2.10
Toluene	0.6275	2.70

The equation of log k in function of log Pow is :

y = (0.4772*x)-0.7214 with a coefficient of determination r²=0.956

y is log k and x is log Pow

Results for the test item:

The retention times of the test item are presented in the following table:

Measurement	Retention Time Peak 1	Retention Time Peak 2
	min.	min.
Measurement 1	1.593	2.100
Measurement 2	1.587	2.100
Measurement 3	1.587	2.100
Mean	1.589	2.100
Standard Deviation	0.003	0.000

The capacity factor (k), log of capacity factor (log k) and log Pow for the test item are presented in the following table:

Peak	Measurement No.	K	log K	log Pow
1	1	0.1018	-0.9923	-0.568
	2	0.0976	-1.0104	-0.606
	3	0.0976	-1.0104	-0.606
	Mean			-0.593
	Stand. Dev.			0.022
2	1	0.4524	-0.3444	0.790
	2	0.4524	-0.3444	0.790
	3	0.4524	-0.3444	0.790
	Mean			0.790
	Stand. Dev.			0.000

log Pow was calculated from the capacity factor as follows:

log Pow= (log K + 0.7214) / 0.4772

Identification of the two peaks of the test item

Distribution of the peaks is presented in the following table:

Measurement	Area Peak 1	Relative Area Peak1	Area Peak 2	Relative Area Peak2
	[mAU*min][1]	[%]	[mAU*min]	[%]
Measurement 1	18.7114	76.875	5.6288	23.125
Measurement 2	17.9410	76.912	5.3856	23.088
Measurement 3	17.9488	76.923	5.3846	23.077
Mean	18.2004	76.9	5.4663	23.1
Standard Deviation	2.43%	0.03%	2.57%	0.11%

The test item contains two main compounds: methacrylic acid and N-[2-(2-Oxoimida­zolidin-1-yl)ethyl]methacrylamide. Using the program EPI Suite (version 4.1) methacrylic acid has a calculated log Pow of 0.99, and N-[2-(2-Oxoimidazolidin-1-yl)ethyl]methacrylamide has a calculated log Pow of -0.66 (epiweb, version 4.1). Therefore, peak 1 (log Pow-0.593) is identified as N-[2-(2-Oxoimidazolidin-1-yl)ethyl]methacrylamide, and peak 2 (log Pow0.790) is identified as methacrylic acid.

Using the correlation log K / log Pow, the log Pow of the two main compounds of the test item were calculated.

The validity criteria and results (mean± standard deviation) are presented in the following table:

Peak	Parameter	Criterion	Found	Assessment
1*	Range (Max – Min. log Pow)	< 0.1	0.038	valid
	Value within Range of Reference Items	0.30 - 2.70	-0.593 ± 0.022	not valid
2*	Range (Max – Min. log Pow)	< 0.1	0.000	valid
	Value within Range of Reference Items	0.30 - 2.70	0.790 ± 0.000	valid

The peak 1 lies within the dead time of the method and not within the range of log Pow of the reference items. Therefore, the corresponding log Pow is stated as < 0.3. It is thus concluded that the test item has a log Pow of < 0.3 – 0.790.These values are the means ± standard deviation of three independent determinations. This range of log Pow is valid for pH 2.4.

Conclusions:

The test item has a log Pow range of <0.3 to 0.790

Executive summary:

The determination of the partition coefficient was performed according to Method A.8 of Commission Regulation No 440/2008 of 30 May 2008, Method 117 of OECD guidelines and GLP. No deviation from the guidelines was observed during the test.

The HPLC method was used for this determination.

The HPLC method covers log Pow in the range of 0 to 6. Reverse phase HPLC is performed on analytical columns packed with a commercially available solid phase containing long hydrocarbon chains (e.g. C8, C18) chemically bound onto silica.

A test item injected on such a column partitions between the mobile solvent phase and the hydrocarbon stationary phase as it is transported along the column by the mobile phase. The test items are retained in proportion to their hydrocarbon-water partition coefficient, with hydrophilic chemicals eluted first and lipophilic chemicals last. The retention times of the peaks of the test item are compared with retention times of reference substances with known hydrocarbon-water partition coefficients.

The test item contains two main compounds: methacrylic acid and N-[2-(2-Oxoimida­zolidin-1-yl)ethyl]methacrylamide. Using the program EPI Suite (version 4.1) methacrylic acid has a calculated log Pow of 0.99, and N-[2-(2-Oxoimidazolidin-1-yl)ethyl]methacrylamide has a calculated log Pow of -0.66 (epiweb, version 4.1). Therefore, peak 1 (log Pow-0.593) is identified as N-[2-(2-Oxoimidazolidin-1-yl)ethyl]methacrylamide, and peak 2 (log Pow0.790) is identified as methacrylic acid.

The peak 1 lies within the dead time of the method and not within the range of log Pow of the reference items. Therefore, the corresponding log Pow is stated as < 0.3.It is thus concluded that the test item has a log Pow of < 0.3 – 0.790.These values are the means ± standard deviation of three independent determinations.This range of log Pow is valid for pH 2.4.

Description of key information

Experimental range for partition coefficient for the test item at pH 2.4 and 25°C = <0.3 to 0.790

Key value for chemical safety assessment

Log Kow (Log Pow):

0.79

at the temperature of:

25 °C

Additional information

The experimental determination of the partition coefficient was performed according to Method A.8 of Commission Regulation No 440/2008 of 30 May 2008, Method 117 of OECD guidelines and GLP. No deviation from the guidelines was observed during the test.

The HPLC method was used for this determination.