Fatty acids, C14-18 and C16-18-unsatd., 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:

03-06-2010 to 23-06-2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

1995

Deviations:

yes

Remarks:

Two vessels were set up in a parallel design at 21 °C ± 1.0 °C instead of 20 ± 1.0 °C. Each vessel had to be sampled several times instead of sampling one vessel at every point in time. This modification helped to avoid weighing errors.

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

2008

Deviations:

yes

Remarks:

Two vessels were set up in a parallel design at 21 °C ± 1.0 °C instead of 20 ± 1.0 °C. Each vessel had to be sampled several times instead of sampling one vessel at every point in time. This modification helped to avoid weighing errors.

Principles of method if other than guideline:

An objective of the column elution method is to increase the surface of the test item to improve the contact with the eluent. This is mostly applicable for organic compounds. In case of metal compounds, the surface cannot be increased by using the column elution method. Thus, the flask method was applied to determine the water solubility of this test item.

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2007-03-21

Type of method:

flask method

Water solubility:

214 µg/L

Conc. based on:

element

Remarks:

dissolved zinc

Loading of aqueous phase:

30 mg/L

Incubation duration:

>= 18 - <= 20 d

Temp.:

21 °C

pH:

>= 5.7 - <= 6

Remarks on result:

other: SD =± 10 µg/L

Observations

During the study, the test media were slightly turbid and undissolved test material was observed on the surface of the media. Furthermore, coarse material was adsorbed to the flask wall. After filtration, the solution was clear. In order to verify this, the turbidity was measured in the supernatant.

After adding the test substance, no distinct effect on pHs of all loaded test media was observed. The temperature in the test vessels ranged from 20.8 – 22.0 °C.

pH values

The pH of test solutions and blanks were measured after 15 days and then every 24 h before sampling until test end. No explicit difference between the pH values of method blanks and media loaded with the test item was observed. All measured pH values are listed in the following tables.

 

Table: pH values of method blanks

stirring time [d]	blank vessel	temperature of pH measurement [°C]	pH	blank vessel	temperature of pH measurement [°C]	pH
15	A	21.1	5.8	B	21.1	5.8
16	A	20.9	5.7	B	20.8	5.7
17	A	22.0	6.0	B	21.7	5.9
18	A	21.3	5.8	B	21.6	5.8
19	A	21.6	5.9	B	21.6	5.9
20	A	21.9	5.9	B	21.9	5.9

Table: pH values of Struktol A 50 P test-solutions

stirring time [d]	blank vessel	temperature of pH measurement [°C]	pH	blank vessel	temperature of pH measurement [°C]	pH
15	A	21.0	5.8	B	21.0	6.0
16	A	20.8	5.8	B	20.9	5.9
17	A	21.9	6.0	B	21.9	6.0
18	A	21.5	5.9	B	21.6	6.0
19	A	21.5	6.0	B	21.4	6.0
20	A	21.7	6.0	B	21.8	6.0

 

Turbidity measurements

The turbidity was measured after filtering to verify that only dissolved zinc concentrations would get measured. The turbidity was always 0.02 NTU, indicating that no undissolved material was left after the filtration. The data of the measurements are compiled in the following Tables.

Table: Turbidity measurements of blanks

stirring time [d]	turbidity of sample blank vessel A [NTU]	turbidity of sample blank vessel B [NTU]
15	0.02	0.02
16	0.02	0.02
17	0.02	0.02
18	0.02	0.02
19	0.02	0.02
20	0.02	0.02

 

Table: Turbidity measurements of samples

stirring time [d]	turbidity of sample sample vessel A [NTU]	turbidity of sample sample vessel B [NTU]
15	0.02	0.02
16	0.02	0.02
17	0.02	0.02
18	0.02	0.02
19	0.02	0.02
20	0.02	0.02

 

 

ICP-OES measurement

Zinc levels of all method blanks from the test were below the respective LODs of 2.8 and 4.7 µg/L. All samples were analyzed within one week.

Table: Measured zinc concentrations in method blank samples

stirring time [d]	mean Zn conc. blank A [µg/L]	mean Zn conc. blank B [µg/L]	LOD [µg/L]	LOQ [µg/L]
15	< LOD	< LOD	4.7	16
16	< LOD	< LOD	4.7	16
17	< LOD	< LOD	4.7	16
18	< LOD	< LOD	4.7	16
19	< LOD	< LOD	2.8	9.4
20	< LOD	< LOD	2.8	9.4

Table: Measured zinc concentrations in test samples

stirring time [d]	Zn conc. of samples vessel A [g/L]	mean Zn conc. + SD vessel A [g/L]	Zn conc. of samples vessel B [g/L]	mean Zn conc.+ SD vessel B [g/L]	mean Zn Mean conc. + SD [g/L] #	variation [%]
15	141	169 ± 24	132	158 ± 23	162 ± 22	-
	183		171
	183		173
16	144	177 ± 29	125	163± 33	170 ± 10	+ 5.1
	193		182
	195		183
17	163	196 ± 29	184	211± 24	203 ± 10	+ 19
	208		222
	217		226
18	180	209 ± 25	159	196 ± 32	202 ± 9.4	- 0.6
	222		215
	224		213
19	196	225 ± 25	184	211 ± 24	218 ± 10	+ 7.8
	239		222
	239		226
20	183	228 ± 39	178	216 ± 33	220 ± 8.9	+ 2.0
	250		235
	252		234

# calculation of mean and standard deviation from mean Zn concentrations of vessel A and B

 

Conclusions:

In a water solubility test (OECD TG 105) with Fatty acids, C14-18 and C16-18-unsatd., zinc salts, the mean dissolved zinc concentration after 18-20 days was determined with 214 ± 10 µg/L at pH 5.7 - 6.0 and 21.0 ± 1.0 °C.

Reference 2

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

supporting 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

Version / remarks:

2001

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2007-03-21

Type of method:

flask method

Specific details on test material used for the study:

- Name of test material (as cited in study report): Zincum SW/F
- Molecular formula: (C16H31O2)2Zn (27.4 %), (C18H35O2)2Zn (67.1 %)
- Molecular weight: (C16H31O2)2Zn 576.22 g/mol, (C18H35O2) 2Zn 632.33 g/mol
- Physical state: solid, white powder

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:

Temp: 21.5 °C, pH: >= 7.8 - <=8.2, 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:

Temp: 21.5 °C, pH: >= 7.8 - <=8.2, 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:

Temp: 21.5 °C, pH: >= 7.8 - <=8.2, 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:

Temp: 21.5 °C, pH: >= 7.8 - <=8.2, modified ISO 6341 media

Under the described conditions, 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 optimisation test, the maximum solubility of the test item Zincum SW/F with a calculated zinc content of 10.05 % resulted in a zinc concentration of 0.284 ± 0.002 mg/L after 24 h 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:

Interpretation of results: 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.

Description of key information

In a water solubility test (OECD TG 105) with Fatty acids, C14-18 and C16-18-unsatd., zinc salts, the mean dissolved zinc concentration after 18-20 days was determined with 214 µg/L at pH 5.7 - 6.0 and 21°C .

Transformation / dissolution of of a structural analogue with a similar water solubility (i.e. Fatty acids, C16-18, zinc salts: up to 180 µg Zn/L) 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 ug Zn/L; after 28 days: 29 ug Zn/L

Loading 10 mg/L: after 7 days: 90 ug Zn/L

Loading 100 mg/L: after 7 days: 369 ug Zn/L

These transformation/dissolution data are considered representative of transformation/ dissolution of Fatty acids, C14-18 and C16-18-unsatd., zinc salts based on a similar water solubility and zinc content (i.e. 10 %). Nevertheless, confirmatory transformation/dissolution testing of Fatty acids, C14-18 and C16-18 unsatd., zinc salts (i.e., finest material as put on the market) in environmental media according to OECD Series #29 (2001) is planned by the of Zinc Metallic Soaps Consortium. The hazard assessment of Fatty acids, C14-18 and C16-18 unsatd., zinc salts will be updated accordingly upon finalisation of the study.

Additional information

The solubility of Fatty acids, C14-18 and C16-18-unsatd., zinc salts depends on several factors, including loading, solution matrix (pH, ionic strength, other salts) and exposure time.

Value used for CSA: 214 µg/L dissolved zinc