Potassium 3-sulphonatopropyl acrylate

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

26 Jul - 21 Aug 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Deviations:

yes

Remarks:

: Determination was performed on the test material in an ionised form.

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

-3.63

Temp.:

21.5 °C

pH:

7.5

Remarks on result:

other: Mean Pow. 2.37E-4, standard deviation 2.99E-5; log D: the measurement was done on fully dissociated substance and concerns sulphonic acid group.

Type:

log Pow

Partition coefficient:

-3.63

Temp.:

21.5 °C

pH:

5

Remarks on result:

other: log D concerns only sulphonic acid group

Type:

log Pow

Partition coefficient:

-3.63

Temp.:

21.5 °C

pH:

9

Remarks on result:

other: log D concerns only sulphonic acid group

Preliminary estimate:

Approximate solubility in n-octanol: <1.88E-2 g/L

Approximate solubility in water: 2.23 g/L

Approximate Pow: < 8.45E-3

log Pow < -2.07

Definitive test:

The mean peak areas obtained for the standard, stock and sample solutions are shown in Tables 2 and 3:

Solution	Mean Peak Area
Standard 0.506 mg/L	3.941
Standard 0.503 mg/L	4.330
Sample 1	1.237
Sample 2	0.982
Sample 3	1.022
Sample 4	1.043
Sample 5	0.967
Sample 6	0.906

Table 2 Organic Phase

Solution	Mean Peak Area
Standard 202 mg/L	1684
Standard 201 mg/L	1669
Sample 1	1730
Sample 2	1732
Sample 3	1733
Sample 4	1728
Sample 5	1812
Sample 6	1806
Stock Solution A	1671
Stock Solution B	1762

Table 3: Aqueous Phase

The total weights (mg) and analysed concentrations (mg/L) of the respective phases are shown in Table 4.

Sample Number	Volume of Water Saturated n-octanol (ml)	Volume of stock solution (ml)	Total weight (mg)*)	Organic Phase		Aqueous Phase
				Analysed Concentration (mg/L)	Total Weight (mg)**)	Analysed Concentration (mg/L)	Total Weight (mg)**)	pH
1	100	200	207	0.302	0.0302	1040	208	7.5
2	105	210	217	0.240	0.0252	1040	219	7.5
3	162	162	167	0.249	0.0404	1040	169	7.5
4	155	155	160	0.254	0.0394	1040	161	7.5
5	200	100	103	0.236	0.0472	1090	109	7.4
6	200	100	103	0.221	0.0442	1090	109	7.4

*) from analysis of the stock solution, **) from analysis of the respective phase

Table 4 Total weights and analysed concentrations of the respective phases

Partition coefficients determined for each sample are collected in Table 5:

Sample Number	n-Octanol/Water Volume Ratio	Partition Coefficient	log Pow	Mean Pow
1	1:2	0.000290	-3.54	0.000260
2	1:2	0.000230	-3.64
3	1:1	0.000240	-3.62	0.000242
4	1:1	0.000245	-3.61
5	2:1	0.000216	-3.67	0.000210
6	2:1	0.000203	-3.69

Table 5 Determined partition coefficients

Description of key information

log Pow = -3.63 at 21.5 °C and pH = 7.5

log D = -3.63 at 21.5 °C and pH = 5

log D = -3.63 at 21.5 °C and pH = 9

Key value for chemical safety assessment

Log Kow (Log Pow):

-3.63

at the temperature of:

21.5 °C

Additional information

The partition coefficient of the substance was determined using the shake-flask method according to the EU Guideline A.8. As the test material was a salt, the determination was performed at an approximately neutral pH. Due to the dissociation constant of the sulphonic acid group (<1), the determination was performed on the test material in an ionised form.

The dissociation constant pKa (0.7) and dissociated and undissociated species distribution vs. pH show that the substance is fully dissociated in pH > 4 and the measured partition coefficient is the distribution coefficient at pH >4 (logPow = log D).