Phosphoric acid, C12-18-alkyl esters, potassium salts

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline available

Principles of method if other than guideline:

The surface tension of Phosphoric acid, C12-18-alkyl esters, potassium salts was measured at 10 different concentrations. The results for surface tension were plotted versus concentration in a graph.
The CMC (critical micelle concentration) was obtained from graphical evaluation.

GLP compliance:

no

Type of method:

other: CMC was determined

Key result

Water solubility:

>= 1.3 - <= 1.5 g/L

Conc. based on:

test mat.

Temp.:

20 °C

Remarks on result:

other: pH not determined

Details on results:

The surface tension is displayed versus the different concentrations graphically (refer to attached document). From this concentration profile it can be estimated that the CMC is reached at concentrations of the pure substance between 1.3 g/L to 1.5 g/L

Concentration of the solution (50%) [in g / L]	Concentration of the pure substance [in g / L]	Surface tension [in mN / m]
		Averagefrom 6 single measurements	Standard deviation
0.68	0.34	41.0	0.6
0.84	0.42	38.7	1.1
1.04	0.52	38.1	1.2
1.61	0.80	36.8	1.4
2.00	1.00	34.4	0.6
2.62	1.31	32.0	0.1
3.01	1.51	31.7	0.1
3.88	1.94	31.6	0.3
6.85	3.42	31.6	0.5
10.53	5.27	30.8	0.1

Conclusions:

The CMC (critical micelle concentration) for Phosphoric acid, C12-18-alkyl esters, potassium salts was estimated based on surface tension measurements.
The results for surface tension were plotted versus concentrations in a graph. The CMC was determined to be between 1.3 g/L to 1.5 g/L from graphical evaluation.

Reference 2

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2017-02-21 to 2017-07-05

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

GLP compliance:

no

Type of method:

flask method

Key result

Remarks on result:

not determinable

Details on results:

It was not possible to determine the water solubility of the test item according to OECD 105 because the insoluble parts of the test item solution could not be removed by centrifugation or filtration.
An emulsion was formed with water. This characteristic of the test item was also observed before freeze drying.
The pH value of a 5% solution of the test item in water was 9.50, the tests were performed at 20 °C.

Conclusions:

It was not possible to determine the water solubility of the test item according to OECD 105 because the insoluble parts of the test item solution could not be removed by centrifugation or filtration.
An emulsion was formed with water. This characteristic of the test item was also observed before freeze drying.
The pH value of a 5% solution of the test item in water was 9.50, the tests were performed at 20 °C.

Description of key information

The CMC for Phosphoric acid, C12-18-alkyl esters, potassium salts was determined to be between 1.3 g/L to 1.5 g/L from graphical evaluation.

Key value for chemical safety assessment

Water solubility:

1.4 g/L

at the temperature of:

20 °C

Additional information

In a study conducted according to OECD guideline 105, it was not possible to determine the water solubility of the test item, because the insoluble parts of the test item solution could not be removed by centrifugation or filtration. It can be assumed that these problems are associated with surface active properties of Phosphoric acid, C12-18-alkyl esters, potassium salts.

As the knowledge of water solubility is of particular importance especially because for determination of partition coefficient none of the experimental methods outlined in the guidelines is applicable to surfactants. Accordingly calculation of Kow value based on the octanol and water solubility is the first choice for such substances.

Following the guidance in “Information Requirements and Chemical Safety Assessment Chapter R.7a (Version 6.0, July 2017)” guidance it is prudent to take the critical micelle concentration in water (CMC) as solubility limit, in order to avoid the artefact of unrealistically low Kow values.

Thus a study was conducted to estimate the CMC of Phosphoric acid, C12-18-alkyl esters, potassium salts based on surface tension measurements.

The results for surface tension were plotted versus concentrations in a graph. The CMC was determined to be between 1.3 g/L to 1.5 g/L from graphical evaluation.