Fatty acids, C18-24, zinc salts

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03.06. - 15.09.2016

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

not performed according to GLP

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Principles of method if other than guideline:

.

GLP compliance:

no

Type of method:

flask method

Key result

Water solubility:

0.63 mg/L

Conc. based on:

element (dissolved fraction)

Loading of aqueous phase:

50 mg/L

Incubation duration:

72 h

Temp.:

20 °C

pH:

7.3

Remarks on result:

other: Mean value of three measurements was < 1 mg/L. The highest value of the three measurements was 0.63 mg/L (0.06 mg Zn/L). This value is taken as key value as the respective endpoint summary field can not deal with "<" values.

Details on results:

Results of the three measurements:
1) pH: 7.00, Zn: 0.06 mg/L
2) pH: 7.26, Zn: <0.05 mg/L
3) pH: 7.66, Zn: <0.05 mg/L

Water solubility of substance Fatty acids, C18-24, zinc salts is < 1mg/L.

Conclusions:

Interpretation of results: slightly soluble
The solubility of the tested substance was < 1 mg/L at 30°C based on the mean value of measured zinc concentrations of 0.06 respectively < 0.05 mg/L and a zinc amount of the test sample of 9.49%. The highest value of the three measurements was 0.63 mg/L (0.06 mg Zn/L). This value is taken as conservative key value.

Description of key information

Water solubility of substance Fatty acids, C18-24, zinc salts: 0.63 mg/L (0.06 mg Zn/L).

Key value for chemical safety assessment

Water solubility:

0.63 mg/L

at the temperature of:

20 °C

Additional information

Water solubility of substance Fatty acids, C18-24, zinc salts is determined according to regulation (EC) No. 440/2008, A.6, ‘flask method’.

Results of the three measurements: 1) 1) pH: 7.00, Zn: 0.06 mg/L; 2) pH: 7.26, Zn: < 0.05 mg/L; 3) pH: 7.66, Zn: < 0.05 mg/L. Thus, the solubility of the tested substance was < 1 mg/L based on the mean value of measured zinc concentrations of 0.06 respectively < 0.05 mg/L and a zinc amount of the test sample of 9.49%. The highest value of the three measurements was 0.63 mg/L (0.06 mg Zn/L). This value is taken as conservative key value.

A water solubility of substance Fatty acids, C18-24, zinc salts of < 1 mg/L, respectively 0.63 mg/L, fits to the water solubility of the structurally similar substance Fatty acids C16-18, zinc salts which has been tested more extensively.

The solubility of substance Fatty acids, C16-18, zinc salts depends on several factors, including loading, solution matrix (pH, ionic strength, other salts) and exposure time.

In water, solubility ranges from 0.3 to 1.8 mg/L depending on test conditions. However, these calculations assume a 1:1 dissolution of zinc and a zinc content of ca. 10%. However, as stearate concentrations have not been experimentally confirmed, it may be more appropriate to express the solubility of substance Fatty acids, C16-18, zinc salts in resulting dissolved zinc concentrations (0.03 to 0.18 mg/L).

In more complex media simulating environmental solutions, solubility resulted in 0.02 to 0.9 mg/L dissolved zinc depending on test conditions. The following dissolved zinc concentrations have been measured in three different studies (most relevant for the classification of substance Fatty acids, C16-18, zinc salts are the data obtained by Schäfers (2010) in transformation dissolution studies (guideline conform and under GLP) for 7 and 28 days with loadings of 1, 10 and 100 mg/L):

Schäfers (2010)

ISO 6341 media at pH 8:

Loading 1 mg/L:

-after 7 days: 19 µg Zn/L

-after 28 days: 29 µg Zn/L

Loading 10 mg/L:

-after 7 days: 90 µg Zn/L

Loading 100 mg/L:

-after 7 days: 369 µg Zn/L

Bouwman (2003)

ISO 6341 at pH 6:

Loading 100 mg/L:

-after 2 days: 208 µg Zn/L

ISO 6341 at pH 8

Loading 100 mg/L:

-after 2 days: 475 µg Zn/L

M7 at pH 6:

Loading 100 mg/L:

-after 2 days: 325 µg Zn/L

M7 at pH 8

Loading 100 mg/L:

-after 2 days: 900 µg Zn/L

Bowmer (2001)

Modified ISO 6341 at pH 6.75:

Loading 10 mg/L:

-after 4 days: 241 µg Zn/L

Modified ISO 6341 at pH 6.75

Loading 100 mg/L:

-after 4 days: 431 µg Zn/L)