Phosphoric acid, 2-ethylhexyl ester

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:

Testing was conducted between 19 May 2011 and 06 August 2011.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions.

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Version / remarks:

The determination was carried out using the HPLC Method designed to be compatible with Method A8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 117 of the OECD Guidelines for Testing of Chemicals

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Method 117 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

< 0.3

pH:

ca. 7

Remarks on result:

other: 2-ethylhexyl dihydrogen phosphate. (Test temp not stated)

Type:

log Pow

Partition coefficient:

2.18

pH:

ca. 7

Remarks on result:

other: Bis(2-ethylhexyl) hydrogen phosphate. (Test temp not stated)

Details on results:

See below.

Results

Preliminary estimate

The partition coefficient was calculated using KOWWIN v1.67a (September 2008) © 2000 U.S. Environmental Protection Agency. The full KOWWIN calculation is presented in Appendix 1 (Attachment 2 - attached background material)).

2-ethylhexyl dihydrogen phosphate:     log₁₀P_ow2.65

Bis(2-ethylhexyl) hydrogen phosphate: log₁₀P_ow6.07

Definitive test

Calibration

The retention times of the dead time and the retention times, capacity factors (k) and log₁₀P_owvalues for the reference standards are shown in the following tables:

Table 10.2

Dead Time	Retention Time (mins)		Mean Retention Time (mins)
	Injection 1	Injection 2
Thiourea	1.777	1.776	1.777

Table10.3

Standard	Retention Time (mins)		Mean Retention Time (mins)	Capacity Factor (k)	Log10k	Log10Pow
	Injection 1	Injection 2
2-Butanone	2.042	2.042	2.042	0.149	-0.826	0.3
Benzene	3.187	3.187	3.187	0.794	-0.100	2.1
Toluene	4.112	4.113	4.113	1.32	0.119	2.7
Naphthalene	5.018	5.020	5.019	1.83	0.261	3.6
Phenanthrene	9.283	9.290	9.287	4.23	0.626	4.5
DDT	27.090	27.116	27.103	14.3	1.15	6.5

Partition coefficient of sample

The retention times, capacity factors and log₁₀P_owvalues determined for the sample are shown in the following table:

Table10.4

Test item component	Injection	Retention Time (mins)	Capacity Factor (k)	Log10k	Log10Pow
2-ethylhexyl dihydrogen phosphate	1	1.403	<0.149	<-0.826	<0.3
	1	1.399	<0.149	<-0.826	<0.3
Bis(2-ethylhexyl) hydrogen phosphate	2	3.059	0.722	-0.142	2.18
	2	3.064	0.725	-0.140	2.18

Table10.5

Test item component	Log10Pow	Partition Coefficient
2-ethylhexyl dihydrogen phosphate	<0.3	<2.00
Bis(2-ethylhexyl) hydrogen phosphate	2.18	150

Conclusions:

The partition coefficients of the test item components have been determined and are:2-ethylhexyl dihydrogen phosphate: Log10 Pow: <0.3Bis(2-ethylhexyl) hydrogen phosphate: Log10 Pow: 2.18

Executive summary:

Method

The determination was carried out using the HPLC Method designed to be compatible with Method A8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 117 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

Conclusion

The partition coefficients of the test item components have been determined and are shown in the following table:

Test item component	Log10Pow	Partition Coefficient
2-ethylhexyl dihydrogen phosphate	<0.3	<2.00
Bis(2-ethylhexyl) hydrogen phosphate	2.18	150

Reference 2

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP test conducted in accordance with internationally accepted Guideline.

Qualifier:

according to guideline

Guideline:

OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)

Deviations:

no

GLP compliance:

yes

Type of method:

shake-flask method to: flask method

Partition coefficient type:

octanol-water

Analytical method:

photometric method

Type:

log Pow

Partition coefficient:

0.7

Temp.:

23 °C

pH:

3.5 - 5.4

Concentration in the aqueous and n-octanol phases in the flasks:

Experiment	1A	1B	2A	2B	3A	3B
Volume of the test item solution (ml)	50	50	25	25	25	25
Volume of n-octanol (ml)	0	0	25	25	75	75
Volume of distilled water (ml)	100	100	50	50	50	50
Total volume of the aqueous phase (ml)	100	100	50	50	50	50
Total volume of the n-octanol phase (ml)	50	50	50	50	100	100
Phosphor concentration found in n-octanol phase (mg/kg)	110	110	63	64	34	37
Phosphor concentration found in aqueous phase (mg/kg)		11		14		11		< 10		< 10		< 10
Phosphor concentration found in n-octanol phase (mg/l)	91	91	52	53	28	31
Phosphor concentration found in aqueous phase (mg/l)	11	14	11	< 10	< 10	< 10
pH aqueous phase (22°C)	3.5	4.6	3.7	5.4	3.9	3.8

The following partition coefficients are calculated from the measured phosphor concentration.

Partition coefficients

Experiment	POW	log POW	Average log POW
1A	8.27	0.92	0.87
1B	6.50	0.81
2A	4.73	0.67	0.70
2B	> 5.30	> 0.72
3A	> 2.80	> 0.45	>0.47
3B	> 3.10	> 0.49
mean values (experiment 1A to 3B)	5.12	0.68	0.7
Standard deviation	2.07	0.18

The partition coefficients calculated from the measured phosphor concentrations decrease with the proportion of n-octanol.

Conclusions:

log POW= 0.7

Executive summary:

The partition coefficient n-octanol/waterof the test item was determined according to the consolidated version of Guideline 67/548/EEC Annex V (Council Directive 92/69/EEC) to log P_OW= 0.7

Description of key information

Log Pow = 2.18 (pH = 7); Butler & White (2011); OECD 117 (HPLC Method)
Log Pow = 0.7 (pH = 3.5-5.4); Winkler (2012); OECD 107 (shake flask)

Key value for chemical safety assessment

Log Kow (Log Pow):

2.18

Additional information

The overall endpoint determination was carried out using the HPLC Method designed to be compatible with Method A8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 117 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

The partition coefficients of the test item components have been determined and are:

2-ethylhexyl dihydrogen phosphate: Log₁₀ Pow: <0.3 (Partition coefficient <2.00)

Bis(2-ethylhexyl) hydrogen phosphate: Log₁₀ Pow: 2.18 (Partition coefficent 150)