Fatty acids, C16-18, zinc salts

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1997-05-22 to 1997-06-26

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

The pH, `the means and st.dev. from at least five samples from the saturation plateau of each run´ and the loading are missing

GLP compliance:

no

Type of method:

column elution method

Water solubility:

0.79 mg/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

24 h

Temp.:

15 °C

Remarks on result:

other: no pH data

Water solubility:

0.97 mg/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

24 h

Temp.:

25 °C

Remarks on result:

other: no pH data

Details on results:

15°C: 2 measurements: 0.621 and 0.970 mg/L
25°C: 2 measurements: 0.961 and 0.980 mg/L

Conclusions:

Slightly soluble (0.1-100 mg/L)
The solubility of the tested substance was 0.79 mg/L at 15 °C and 0.97 mg/L at 25 °C under these experimental conditions.

Reference 2

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

no data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

loading is missing

GLP compliance:

not specified

Type of method:

column elution method

Water solubility:

1.8 mg/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

>= 12 - <= 16 h

Temp.:

20 °C

pH:

7.3

Remarks on result:

other: Mean of two runs with each five measurements

Details on results:

1st trial: Mean/SD [mg/L]: 1.5 / 0.1 at pH 7.13 / 0.71
12 h: 1.5 mg/L at pH 8.17
13 h: 1.4 mg/L at pH 7.22
14 h: 1.4 mg/L at pH 7.33
15 h: 1.7 mg/L at pH 6.35
16 h: 1.6 mg/L at pH 6.59

2nd trial: Mean/SD [mg/L]: 2.1 / 0.1 at pH 7.46 / 0.62
12 h: 2.0 mg/L at pH 8.13
13 h: 2.1 mg/L at pH 6.8
14 h: 1.9 mg/L at pH 7.78
15 h: 2.2 mg/L at pH 7.78
16 h: 2.2 mg/L at pH 6.8

Conclusions:

Slightly soluble (0.1-100 mg/L)
The solubility of the tested substance was 1.8 mg/L at 20 °C under these experimental conditions.

Reference 3

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-12-15 to 2010-05-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Series on Testing and Assessment No. 29 (23-Jul-2001): Guidance document on transformation/dissolution of metals and metal compounds in aqueous media

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2007-03-21

Type of method:

flask method

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

>= 0.017 - <= 0.023 mg/L

Element analysed:

Zn

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

21.5 °C, pH 7.8 - 8.2

Remarks on result:

other: modified ISO 6341 media

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

>= 0.082 - <= 0.098 mg/L

Element analysed:

Zn

Loading of aqueous phase:

10 mg/L

Incubation duration:

7 d

Test conditions:

21.5 °C, pH 7.8 - 8.2

Remarks on result:

other: modified ISO 6341 media

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

>= 0.362 - <= 0.376 mg/L

Element analysed:

Zn

Loading of aqueous phase:

100 mg/L

Incubation duration:

7 d

Test conditions:

21.5 °C, pH 7.8 - 8.2

Remarks on result:

other: modified ISO 6341 media

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

>= 0.025 - <= 0.033 mg/L

Element analysed:

Zn

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

21.5 °C, pH 7.8 - 8.2

Remarks on result:

other: modified ISO 6341 media

Under the described conditions of this test, the highest dissolved zinc concentrations at 21.5 ± 1.5 °C were measured in solutions at pH 8.0 ± 0.2. At a loading of 100 mg/L in the screening/pH optimization test, the maximum solubility of the test item zincum with a calculated zinc content of 10.05 % resulted in a zinc concentration of 0.284 ± 0.002 mg/L after 24h corresponding to a dissolved zinc amount of 2.9 %. In the full T/D test, the maximum solubility resulted in 0.029 ± 0.004 mg/L dissolved zinc (28 %) at the 1 mg/L loading after 28 days, and in 0.090 ± 0.008 mg/L (8.9 %) and 0.369 ± 0.007 mg/L (3.7 %) at the 10 mg/L and 100 mg/L loading, respectively, after 7 days.

Conclusions:

Slightly soluble (0.1-100 mg/L) at pH 8 (pH that maximises dissolution)
In the full T/D test, the maximum solubility resulted in 0.029 ± 0.004 mg/L dissolved zinc (28 %) at the 1 mg/L loading after 28 days, and in 0.090 ± 0.008 mg/L (8.9 %) and 0.369 ± 0.007 mg/L (3.7 %) at the 10 mg/L and 100 mg/L loading, respectively, after 7 days in modified ISO 6341 media at pH 8.

Reference 4

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2003

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Series on Testing and Assessment No. 29 (23-Jul-2001): Guidance document on transformation/dissolution of metals and metal compounds in aqueous media

Deviations:

yes

Remarks:

- No air tight vessels were incubated. - Temperature and oxygen content were not measured during the test as appropriate concentrations were assumed under the experimental conditions.

GLP compliance:

yes (incl. QA statement)

Type of method:

other: static without interim renewal of test solutions

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

208 µg/L

Element analysed:

Zn

Loading of aqueous phase:

100 mg/L

Incubation duration:

48 h

Test conditions:

20 °C, pH 6

Remarks on result:

other: Treatment (III): total soluble zinc as a measure of dissolved zinc after 48 h in ISO medium (silanised test vessel): 208 µg/L

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

475 µg/L

Element analysed:

Zn

Loading of aqueous phase:

100 mg/L

Incubation duration:

48 h

Test conditions:

20 °C, pH 8

Remarks on result:

other: Treatment (IV): total soluble zinc as a measure of dissolved zinc after 48 h in ISO medium (silanised test vessel): 475 µg/L

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

325 µg/L

Element analysed:

Zn

Loading of aqueous phase:

100 mg/L

Incubation duration:

48 h

Test conditions:

20 °C, pH 6

Remarks on result:

other: Treatment (VII): total soluble zinc as a measure of dissolved zinc after 48 h in M7 medium (silanised test vessel): 325 µg/L

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

900 µg/L

Element analysed:

Zn

Loading of aqueous phase:

100 mg/L

Incubation duration:

48 h

Test conditions:

20 °C, pH 8

Remarks on result:

other: Treatment (VIII): total soluble zinc as a measure of dissolved zinc after 48 h in M7 medium (silanised test vessel): 900 µg/L

Details on results:

Results (duplicates):
Solubility Ionic Zn (after 48 h static) [µg/L]
(I) 112 - 151
(II) 400 - 470
(III) 154 - 168
(IV) 330 - 430
(V) 230 - 240
(VI) 750 - 810
(VII) 260 - 300
(VIII) 830 - 850

Total Soluble Zn (after 48 h static) [µg/L]
(I) 162 - 199
(II) 410 - 460
(III) 196 - 220 (Mean: 208, mean solubility of test substance: 2011)
(IV) 470 - 480 (Mean: 475, mean solubility of test substance: 4593)
(V) 300 - 310
(VI) 760 - 790
(VII) 310 - 340 (Mean: 325, mean solubility of test substance: 3143)
(VIII) 890 - 910 (Mean: 900, mean solubility of test substance: 8703)

Total Zn (after 48 h static) [µg/L]
(I) 210 - 220
(II) 410 - 470
(III) 410 - 440
(IV) 470 - 500
(V) 300 - 330
(VI) 770
(VII) 360 - 480
(VIII) 850 - 880

Conclusions:

Slightly soluble (0.1-100 mg/L)
At a loading of 100 mg/L, the solubility of the tested substance resulted in zinc concentrations of 0.208 and 0.475 mg/L at pH 6 and pH 8, respectively, in ISO 6341 medium at 20°C after 48 hours under these experimental conditions.
At a loading of 100 mg/L, the solubility of the tested substance resulted in zinc concentrations of 0.325 and 0.900 mg/L at pH 6 and pH 8, respectively, in M 7 medium at 20°C after 48 hours under these experimental conditions.

Reference 5

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD Series On Testing And Assessment Number 29, Guidance document on transformation/dissolution of metals and metal compounds in aqueous media

Deviations:

yes

Remarks:

- pH of solutions is different

Principles of method if other than guideline:

- No air tight vessels were incubated.
- Temperature and oxygen content were not measured during the test as appropriate concentrations were assumed under the experimental conditions.
- No solubility experiments on pH value at approx. 8.5 was performed.

GLP compliance:

not specified

Type of method:

other: static without interim renewal of test solutions

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

241 µg/L

Element analysed:

Zn

Loading of aqueous phase:

10 mg/L

Incubation duration:

96 h

Test conditions:

23 °C, pH 6.7-6.8,

Remarks on result:

other: Dissolved free zinc (Zn2+) after 96 h in modified ISO 6341 medium at a loading of 10 mg/L: 241 µg/L

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

431 µg/L

Element analysed:

Zn

Loading of aqueous phase:

100 mg/L

Incubation duration:

96 h

Test conditions:

23 °C, pH 6.7-6.8

Remarks on result:

other: Dissolved free zinc (Zn2+) after 96 h in modified ISO 6341 medium at a loading of 100 mg/L: 431 µg/L

Details on results:

Dissolved free zinc (Zn2+) concentrations measured (average):

Loading: 10mg/L filtered):
24h: 254µg/L
96h: 241µg/L (2331 ug/L test substance)

Loading: 10mg/L (unfiltered):
24h: 272µg/L
96h: 263µg/L

Loading: 100mg/L (filtered):
24h: 497µg/L
96h: 431µg/L (4168 ug/L test substance)

Loading: 100mg/L (unfiltered):
24h: 376µg/L
96h: 386µg/L

Conclusions:

Slightly soluble (0.1-100 mg/L)
The loading rate of 10 mg /L zinc distearate yielded concentrations of 241 μg Zn/L at pH 6.75 in OECD medium at 23°C after 96 hours under these experimental conditions.
The loading rate of 100 mg/L- zinc distearate yielded concentrations of 431 μg Zn/L at pH 6.75 in OECD medium at 23°C after 96 hours under these experimental conditions..

Reference 6

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2007-04 to 2001-06

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

other: Draft Guidance Document on Transformation/Dissolution of Metals and Metal Compounds in Aqueous Media

Deviations:

yes

Remarks:

Please refer to the field `Principles of method if other than guideline´

Principles of method if other than guideline:

The developed analytical method is based on the chelation of free zinc resulting in a colouring of the sample, which then is quantified by photometry. The method was suited to determine zinc concentrations with the requested sensitivity (10 µg Zn/L).
The original method (from the zinc kid) is certified to determine a wide range of zinc concentrations in for instance blood or plasma. This method includes the dilution with an iron stripping solution, which makes the method robust against interference by iron, however, it also reduces the sensitivity to a level that is insufficient for the current study. The method was therefore modified by adjusting the volume ratio of the sample and the reagent solutions from 1:4 to 1:1 in order to increase the sensitivity of the method.

GLP compliance:

no

Type of method:

other: analytical photometric method to measure free zinc ions

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

34.3 µg/L

Element analysed:

Zn

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

30 °C

Remarks on result:

other: Zinc distearate filtered, 24h

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

60.8 µg/L

Element analysed:

Zn

Loading of aqueous phase:

100 mg/L

Incubation duration:

168 h

Test conditions:

30 °C

Remarks on result:

other: Zinc distearate filtered, 168h

Details on results:

The concentration of zinc in the filtrated zinc distearate solution was about 34 µg/l after 24 hours contact time and about 60 µg/l after 168 hours contact time. The free zinc concentration in the outflow of the C18 Seppa cartridge was about 3 µg/l after 24 hours and it was below the detection level after 168 hours.

The dissolution of about 100 mg/l zinc stearate in water was tested and 34 to 60 µg/l dissolved zinc were measured with the photometric method. These measurements might include non-cationic zinc species present in the filtrated zinc stearate solution which dissociated during the derivation.

Zinc stearate has a reported water solubility of 0.9 mg/l, and ecotoxicity tests should normally be carried out up to the aqueous solubility of a test substance. The free zinc concentration at a loading of 0.9 mg/l can be expected to be lower than at 100 mg/l, which, however, needs to be confirmed experimentally. 

Conclusions:

Insoluble (< 0.1 mg/L)
The dissolution of about 100 mg/l zinc stearate was tested and 34 to 60 µg/l were measured with the photometric method.

Description of key information

The solubility of Fatty acids, C16 -18, zinc salts resulted in 0.03 to 0.18 mg/L dissolved zinc depending on test conditions.

   

Transformation / dissolution of Fatty acids, C16 -18, zinc salts at pH 8 (the pH that maximises dissolution) resulted in the following dissolved zinc concentrations in modified ISO 6341 media:

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

Additional information

The solubility of 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 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 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)