Phosphoric acid, 2-ethylhexyl ester, ammonium salt

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

weight of evidence

Study period:

07 March 2018 - 27 April 2018

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)

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:

other: Not applicable - estimation method

Key result

Type:

log Pow

Partition coefficient:

>= -1.9 - <= -1.6

Temp.:

20 °C

Remarks on result:

other: Calculated value

Data Evaluation

The partition coefficient is estimated from the ratio of the solubilities of the test item in the pure solvents.

 

P_{ow estimate}= saturation c_n-octanol/ saturation c_water

 

Table 1:          Solubility in n-octanol (at 20 ± 2 °C, 1st test)

Weight of Test Item (mg)	Volume n-octanol (ml)	Duration of Shaking (min)	Remarks
50.3 mg	50	10	not dissolved
	100	10	not dissolved
	250	10	not dissolved
	500	10	dissolved completely no light scattering solubility 101 mg/l – 201 mg/l

 

Table 2:          Solubility in n-octanol (at 20 ± 2 °C, 2nd test)

Weight of Test Item (mg)	Volume n-octanol (ml)	Duration of Shaking (min)	Remarks
22.0	110	19	not dissolved; solubility < 200 mg/l

 

The second test was performed to show that a longer shaking time does not lead to a higher solubility. The lower limit value from Test 1 and the limit value from Test 2 have been used in the subsequent calculations.

 

The critical micelle concentration of the undried test item was measured using ISO 4311:1979 and mean measured value of 9536 mg/l was determined⁽¹⁾. Regarding the water content of the undried test item of 24.1 %, the water solubility of the dried test item is calculated to 7238 mg/l. As the test item is surface active, the critical micelle concentration of the test item is used as a surrogate value for the water solubility.

 

Based on the above results the maximum and minimum estimated P_owcan be calculated as:

 

P_{ow max}= maximum saturation concentration n-octanol/minimum saturation concentration water = 200 mg/l / 7238 mg/l = 0.028.

Log P_{ow max}= Log 0.028 = -1.6.

 

P_{ow min}= minimum saturation concentration n-octanol/maximum saturation concentration water = 101 mg/l / 7238 mg/l = 0.014.

Log P_{ow min}= Log 0.014= -1.9.

 

Therefore, the log P_OW is calculated to be between -1.9 and -1.6 at 20 ± 2 °C.

 

 

⁽¹⁾Anon (2017): Use of processor Tensiometer K100 in combination with the double dosing unit for characterization of cristical micelle concentrations, Source: KRÜSS GmbH, Borsteler Chaussee 85, 22453 Hamburg, Germany. Unpublished report No.: Not Applicable. Date: 17 November 2017.

Conclusions:

The log POW of the test item is calculated to be between -1.9 and -1.6 at 20 ± 2 °C

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.

Due to the test item containing 24.1 % (w/w) water, this test was conducted on a dry basis.  The test item was dried by the Sponsor prior to testing using rotary evaporation.  Aliquots of dried test item (22.0 - 50.3 mg) were placed in a glass vessel, n-octanol was added in a stepwise manner.  After each addition of n-octanol, the vessel was shaken for at least 10 min.  The sample was then visually checked for undissolved test item.  If the test item was not dissolved further n-octanol was added in the manner previously described.  The test was performed at 20 ± 2.0 °C.

For the test item an estimated partition coefficient of log P_ow = -1.9 to -1.6 at a temperature of 20 ± 2.0 °C was determined.

Reference 2

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

14 December 2017 - 26 April 2018

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

unsuitable test system

Remarks:

Whilst the study has been conducted according to the guideline method under GLP conditions. The test item is a complex substance that has been determined to be surface active. As such this study must be regarded as not reliable. The nature of the test item means that there is the potential for secondary column interactions to occur, leading to a potential overestimation of the partition coefficient. To mitigate against this phenomenon, this study is being used as a part of a weight of evidence for this endpoint.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Regulation (EC) 440/2008 of 30 May 2008

Deviations:

yes

Remarks:

The study was conducted on a surface active substance.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

April 2004

Deviations:

yes

Remarks:

The study was conducted on a surface active substance.

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:

<= 3.23

Temp.:

20 °C

Remarks on result:

other: Mean Value

Remarks:

Two measurements were made under identical conditions, using the same set of reference items that fall within a range of ± 0.1 log units. Therefore the quality criteria outlined in OECD 117 have been fulfilled.

Data Evaluation

Calculation of log k – The corresponding logarithms of the capacity factors, log k, were calculated from the retention times and the dead time.

Calibration Graph – A correlation graph of log k versus log Pow was plotted.

Sample Results – The partition coefficient of the test item was obtained by interpolation from the calibration graph, using the calculated capacity factor.

 

 

Table 3:          Retention time and log Pow of the test item (mean of two runs)

	Retention time [min]*	Mean retention time [min]	Mean retention time of two runs [min]	Absolute deviation [min]	Log POWdetermined	Mean log POW	Mean log Powof two runs**	Absolute deviation of log Pow
Run 1 – Injection 1 (Peak Start)	2.283	2.260	2.27	0.03	< 0.0***	< 0.0***	< 0.0***	Not Applicable
Run 1 – Injection 2 (Peak Start)	2.201				< 0.0***
Run 1 – Injection 3 (Peak Start)	2.331				< 0.0***
Run 1 – Injection 4 (Peak Start)	2.223				< 0.0***
Run 2 – Injection 1 (Peak Start)	2.186	2.289			< 0.0***	< 0.0***
Run 2 – Injection 2 (Peak Start)	2.332				< 0.0***
Run 2 – Injection 3 (Peak Start)	2.311				< 0.0***
Run 2 – Injection 4 (Peak Start)	2.326				< 0.0***
Run 1 – Injection 1 (Peak End)	9.284	9.425	9.47	0.09	3.20	3.22	3.23	0.01
Run 1 – Injection 2 (Peak End)	9.338				3.21
Run 1 – Injection 3 (Peak End)	9.334				3.21
Run 1 – Injection 4 (Peak End)	9.742				3.27
Run 2 – Injection 1 (Peak End)	9.296	9.512			3.20	3.23
Run 2 – Injection 2 (Peak End)	9.569				3.24
Run 2 – Injection 3 (Peak End)	9.752				3.27
Run 2 – Injection 4 (Peak End)	9.430				3.22

*The retention time of the test item was detected using an Evaporative Light Scattering Detector (ELSD). Therefore the detected retention time was corrected by the time shift of 0.065 min between PDA detector (used for reference items) and ELS detector (used for test item).

**The test item eluates as two separate signal areas. Therefore the start of the first signal area and the end of the second signal area were used to calculate the range of the log Pow.

***below determination limit of the method (0.0 according to OECD 117 and EC method A.8)

 

 

Table 4:          Calibration parameter obtained from first run

	Slope	x	Intercept
Log Pow =	2.569895	log k	+ 1.73153
R =	0.9977

 

 

Table 5:          Calibration parameter obtained from second run

	Slope	x	Intercept
Log Pow =	2.567665	log k	+ 1.731722
R =	0.9977

 

 

Table 6:          Values for determination of Pow, dead time and calibration graph obtained from 1st run

Name	Log Pow nominal	RT* [min]	Mean RT [min]	SD [min]	log k	Log Powdetermined	Mean log Pow	SD log Pow
Test Item (start of the first signal area)	---	2.283	2.260	0.059	-0.788	< 0.0***	< 0.0***	0.00
		2.201			-0.916	< 0.0***
		2.331			-0.727	< 0.0***
		2.223			-0.878	< 0.0***
Test Item (end of the second signal area)	---	9.284	9.425	0.213	0.572	3.20	3.22	0.03
		9.338			0.575	3.21
		9.334			0.575	3.21
		9.742			0.598	3.27
Thiourea**	---	1.963	1.963	0.000	---	---	---	---	Dead time
		1.963
		1.963
		1.964
2-Butanone	0.3	2.558	2.560	0.001	-0.518	0.40	0.40	0.00	Reference Items
		2.560			-0.517	0.40
		2.560			-0.517	0.40
		2.560			-0.517	0.40
Acetanilide	1.0	2.898	2.900	0.002	-0.322	0.90	0.91	0.01
		2.900			-0.321	0.91
		2.900			-0.321	0.91
		2.902			-0.320	0.91
Nitrobenzene	1.9	4.363	4.366	0.002	0.087	1.96	1.96	0.00
		4.366			0.088	1.96
		4.366			0.088	1.96
		4.369			0.088	1.96
Atrazine	2.6	5.720	5.723	0.003	0.282	2.46	2.46	0.00
		5.725			0.282	2.46
		5.721			0.282	2.46
		5.727			0.283	2.46
Diphenylamine	3.4	11.087	11.099	0.008	0.667	3.45	3.45	0.00
		11.101			0.668	3.45
		11.100			0.668	3.45
		11.107			0.668	3.45
Benzylbenzoate	4.0	17.312	17.345	0.024	0.893	4.03	4.03	0.00
		17.341			0.894	4.03
		17.363			0.895	4.03
		17.362			0.895	4.03

*The retention time of the test item was detected using an Evaporative Light Scattering Detector (ELSD). Therefore the detected retention time was corrected by the time shift of 0.065 min between PDA detector (used for reference items) and ELS detector (used for test item).

**Thiourea was used for determination of the dead time; RT = retention time; SD = standard deviation

***below determination limit of the method (0.0 according to OECD 117 and EC method A.8)

 

 

Table 7:          Values for determination of Pow, dead time and calibration graph obtained from 2nd run

Name	Log Pow nominal	RT [min]*	Mean RT [min]	SD [min]	log k	Log Pow determined	Mean log Pow	SD log Pow
Test Item (start of the first signal area)	---	2.186	2.289	0.069	-0.947	< 0.0***	< 0.0***	0.00
		2.332			-0.727	< 0.0***
		2.311			-0.753	< 0.0***
		2.326			-0.734	< 0.0***
Test Item (end of the second signal area)	---	9.296	9.512	0.195	0.572	3.20	3.23	0.03
		9.569			0.588	3.24
		9.752			0.598	3.27
		9.430			0.580	3.22
Thiourea**	---	1.964	1.964	0.001	---	---	---	---	Dead time
		1.965
		1.962
		1.963
2-Butanone	0.3	2.561	2.560	0.003	-0.517	0.40	0.40	0.00	Reference Items
		2.564			-0.515	0.41
		2.557			-0.520	0.40
		2.558			-0.519	0.40
Acetanilide	1.0	2.902	2.901	0.005	-0.321	0.91	0.91	0.01
		2.907			-0.319	0.91
		2.897			-0.323	0.90
		2.898			-0.323	0.90
Nitrobenzene	1.9	4.371	4.368	0.007	0.088	1.96	1.96	0.00
		4.377			0.089	1.96
		4.362			0.087	1.96
		4.363			0.087	1.96
Atrazine	2.6	5.732	5.729	0.013	0.283	2.46	2.46	0.00
		5.745			0.284	2.46
		5.717			0.281	2.45
		5.720			0.282	2.46
Diphenylamine	3.4	11.121	11.122	0.031	0.669	3.45	3.45	0.01
		11.165			0.671	3.45
		11.092			0.667	3.44
		11.111			0.668	3.45
Benzylbenzoate	4.0	17.364	17.376	0.039	0.894	4.03	4.03	0.01
		17.414			0.896	4.03
		17.327			0.893	4.02
		17.400			0.895	4.03

*The retention time of the test item was detected using an Evaporative Light Scattering Detector (ELSD). Therefore the detected retention time was corrected by the time shift of 0.065 min between PDA detector (used for reference items) and ELS detector (used for test item).

**Thiourea was used for determination of the dead time; RT = retention time; SD = standard deviation

***below determination limit of the method (0.0 according to OECD 117 and EC method A.8)

 

 

Conclusions:

The test item was determined to have a mean partition coefficient (Log Pow) of < 3.23 at a mean temperature of 20 ± 1.0 °C.

Executive summary:

EU Method A.8. – The partition coefficient of the test item was determined using the HPLC and calculation methods.  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.

Analysis was performed using a solid phase of long hydrocarbon chains chemically bound onto silica (Luna 5µ C18(2) 100A; 250 x 3.0 mm), with a mobile phase mixture of 67.5 % methanol and 32.5 % ultra-pure water.  A PDA detector was used at 220 nm to detect the reference solution, an ELS detector was used to detect the test item.  Reference items were used to determine column dead time and regression coefficients.

For the test item a partition coefficient of log Pow ≤ 3.23 was determined at a temperature of 20 °C ± 1 °C.

Description of key information

Partition coefficient: Log Pow = ≥ -1.9 to ≤ -1.6 at 20 °C ± 2.0 °C; EU Method A.8. (Estimation Method (Solubility Ratio)); C. Bär (2018)

Partition coefficient: Log Pow= ≤ 3.23 at 20.0 °C ± 1.0 °C; EU Method A.8. (HPLC Method); C. Bär (2018)

Key value for chemical safety assessment

Log Kow (Log Pow):

-1.6

at the temperature of:

20 °C

Additional information

The partition coefficient of the test item was determined using the HPLC and calculation methods.  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.

HPLC Method: Analysis was performed using a solid phase of long hydrocarbon chains chemically bound onto silica (Luna 5µ C18(2) 100A; 250 x 3.0 mm), with a mobile phase mixture of 67.5 % methanol and 32.5 % ultra-pure water.  A PDA detector was used at 220 nm to detect the reference solution, an ELS detector was used to detect the test item.  Reference items were used to determine column dead time and regression coefficients. For the test item a partition coefficient of log Pow ≤ 3.23 was determined at a temperature of 20 °C ± 1 °C.

As part of the wider testing programme it was determined experimentally that the test item is surface active (C. Bär, EU Method A.5. (2017)).  As per EU Method A.8., neither the shake-flask method nor the HPLC method is applicable to surface active substances.  Potentially misleading results may arise due to emulsification (flask method) or secondary column interactions (HPLC Method).  As such the HPLC Method should be regarded as supplementary information as part of a weight of evidence based on the calculation method.

Estimation Method (Solubility Ratio):  Due to the test item containing 24.1 % (w/w) water, this test was conducted on a dry basis.  The test item was dried by the Sponsor prior to testing using rotary evaporation.  Aliquots of dried test item (22.0 - 50.3 mg) were placed in a glass vessel, n-octanol was added in a stepwise manner.  After each addition of n-octanol, the vessel was shaken for at least 10 min.  The sample was then visually checked for undissolved test item.  If the test item was not dissolved further n-octanol was added in the manner previously described.  The test was performed at 20 ± 2.0 °C. For the test item an estimated partition coefficient of log Pow = -1.9 to -1.6 at a temperature of 20 ± 2.0 °C was determined.

A log Kow value of -1.6 was used for chemical safety assessment.