Oleic acid, copper salt

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018-11-30 to 2019-01-17

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline 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, each vessel was sampled several times instead of sampling one vessel at every point in time/ exclusion of O2 and CO2, under inert gas (argon)

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, each vessel was sampled several times instead of sampling one vessel at every point in time/ exclusion of O2 and CO2, under inert gas (argon)

GLP compliance:

yes (incl. QA statement)

Remarks:

2019-07-15

Type of method:

flask method

Specific details on test material used for the study:

Appearance: highly viscous, sticky, green-blue
Storage conditions: Keep container tightly closed, in a dry place at room temperature

Water solubility:

8.33 mg/L

Conc. based on:

test mat. (dissolved fraction)

Loading of aqueous phase:

100 mg/L

Incubation duration:

>= 36 - <= 44 d

Temp.:

20 °C

pH:

>= 5.2 - <= 5.9

Remarks on result:

other: S.D.: ± 1.40 mg/L

Remarks:

calculated based on a copper content of 9.6 %

Water solubility:

800 µg/L

Conc. based on:

element (dissolved fraction)

Remarks:

copper

Loading of aqueous phase:

100 mg/L

Incubation duration:

>= 36 - <= 44 d

Temp.:

20 °C

pH:

>= 5.2 - <= 5.9

Remarks on result:

other: S.D.: ± 135 μg/L

Details on results:

Observations
In the preliminary test undissolved substance (probably test item) adhered to the bottom of the vessels, whereas in the main test the substance adhered to the sample boats. Sample boats were transferred inside the test vessels prior to start. For the method blank vessels, blank sample boats were added to the ultrapure water.

Temperature and oxygen
The mean temperatures were 20.1 ± 0.2 °C and 20.2 ± 0.1 °C during the test after the pre saturation phase at 30.0 ± 2.0 °C. A peak at 18.1 ° C was observed on January 10, 2019. The reason for this was that the data logger had to be removed from the incubation cabinet due to a battery change. This has no influence on the validity and integrity of the study.
No oxygen was detectable during the experimental study phase.

pH values
The pH of test item solutions ranged between 5.2 and 5.9 whereas the pH of method blanks remained within 6.9 and 7.7.

Turbidity
The turbidity in samples from the test was always < 1 NTU indicating that filtered solutions did not contain any undissolved material.

Analytical measurements
The calculated amount of test item dissolved is based on the amount of dissolved copper. The measured background concentrations were less than LOD and far below the measured copper concentrations in test item solution. Hence, no background correction was performed.

ICP-OES measurement with corresponding LOD/LOQ, correlation coefficient and sum of quality assurance samples and recovery (non GLP preliminary test).

Calibration [µg/L] – lowest and highest calibration point	Chosen wavelength [nm]	LOD [µg/L]	LOQ [µg/L]	Correlation coefficient	Sum of quality assurance samples	Recovery of quality assurance samples [%]
February 19, 2018 measurement of samples from non GLP preliminary test
1.0 – 1000 (total of 13 calibration points, 13 used + blank)	213.598	0.285	0.856	0.99979	24	100
December 17, 2018; measurement of method blanks (days 8, 9, 10)
2.5 – 1000 (total of 13 calibration points, 12 used + blank)	327.395	1.79	5.37	1.00000	16	100
December 18, 2018; measurement of test item loaded samples (days 8, 9, 10)
2.5 – 1000 (total of 13 calibration points, 12 used + blank)	327.395	2.05	6.15	1.00000	15	100
January 11, 2019; measurement of test samples and method blanks (days 36, 37, 38)
5 – 1000 (total of 13 calibration points, 11 used + blank)	327.395	0.626	1.88	0.99993	19	100
January 17, 2019; measurement of test samples and method blanks (days 42, 43, 44)
2.5 – 1000 (total of 13 calibration points, 12 used + blank)	213.598	0.601	1.80	0.99995	19	100

Copper recovery/validation data of measurement series

Element Cu	Recovery [%]	SD [%]	n (total)	n (valid)
February 19, 2018        (non GLP preliminary test)
Quality control standard (Roth) 75 µg/L	106	1	4	4
TMDA-70.2 (lot 0916, dilution factor 10), nominal value Cu: 407 µg/L – diluted 40.7 µg/L	101	2	4	4
Recalibration standard 250 µg/L	101	1	4	4
TMDA-70.2 (lot 0916) nominal value Cu: 407 µg/L	111	1	4	4
Quality control standard (Roth) 750 µg/L	106	<1	4	4
December 17, 2018
Quality control standard (Roth) 100 µg/L	104	1	4	4
TMDA-70.2 (lot 0618, dilution factor 2) nominal value Cu: 406 µg/L – diluted 203 µg/L	105	1	4	4
Recalibration standard 500 µg/L	98.8	0.9	4	4
Quality control standard (Roth) 750 µg/L	103	1	4	4
December 18, 2018
Quality control standard (Roth) 75 µg/L	104	<1	3	3
TMDA-70.2 (lot 0618, dilution factor 2), nominal value Cu: 406 µg/L – diluted 203 µg/L	106	<1	3	3
Recalibration standard 100 µg/L	106	<1	3	3
Quality control standard (Roth) 750 µg/L	105	<1	3	3
January 11, 2019
Quality control standard (Roth) 75 µg/L	101	1	4	4
TMDA-70.2 (lot 0618, dilution factor 2), nominal value Cu: 406 µg/L – diluted 203 µg/L	102	1	4	4
Recalibration standard 100 µg/L	99.3	1.2	4	4
Quality control standard (Roth) 750 µg/L	101	1	4	4
January 17, 2019
Quality control standard (Roth) 75 µg/L	101	1	4	4
TMDA-70.2 (lot 0618, dilution factor 2), nominal value Cu: 406 µg/L – diluted 203 µg/L	104	2	4	4
Recalibration standard 100 µg/L	97.4	0.6	4	4
Quality control standard (Roth) 750 µg/L	102	1	4	4

 Fortification of measurement series on December 18, 2018

Sample	Element	Measured concentration [µg/L]	Calculated level after addition [µg/L]	Recovery [µg/L] / [%]
December 18, 2018
Vessel 3 sample a 8d (dilution 10-fold) – 1 mL sample 4 mL 250 µg/L standard	Cu	83.0	217	216 / 99.9
Vessel 4 sample a 9d (dilution 10-fold) – 1 mL sample 4 mL 500 µg/L standard	Cu	101	420	423 / 101
Vessel 5 sample a 10d (18Y0233; dilution 10-fold) – 1 mL sample 4 mL 750 µg/L standard	Cu	104	621	626 / 101
January 11, 2018
Vessel 3 sample a 27d (dilution 10-fold) – 1 mL sample 4 mL 250 µg/L standard	Cu	62.7	213	211 / 99.4
Vessel 4 sample a 38d (dilution 10-fold) – 1 mL sample 4 mL 500 µg/L standard	Cu	92.9	419	421 / 101
Vessel 5 sample a 38d (dilution 10-fold) – 1 mL sample 4 mL 750 µg/L standard	Cu	79.9	616	632 / 103
January 17, 2018
Vessel 3 sample a 43d (dilution 2-fold) – 1 mL sample 4 mL 500 µg/L standard	Cu	334	467	469 / 100
Vessel 4 sample a 44d (dilution 2-fold) – 1 mL sample 4 mL 1000 µg/L standard	Cu	485	897	905 / 101
Vessel 5 sample a 45d (dilution 2-fold) – 1 mL sample 4 mL 750 µg/L standard	Cu	425	685	677 / 98.8

 

A solubility equilibrium (difference in concentrations between two subsequent sampling points has to be less than 15 %) was already observed in the beginning of the test. However, increasing concentrations were measured. No increasing in copper concentrations and a difference of less than 15 % was determined from 36 d until test end (44 d). Thus, the validity criteria as foreseen in OECD 105 guideline are fulfilled.

Therefore, the determination of the water solubility of Oleic acid, copper salt is based on mean dissolved Cu concentrations of sampling days (36, 37, 38, 42, 43 and 44 d) and a copper amount of 9.6 % in the test item:

Mean Cu concentrations:

Vessel 3: 636 ± 21 μg/L

Vessel 4: 955 ± 23 μg/L

Vessel 5: 808 ± 29 μg/L

Mean: 800 ± 135 μg/L

The water solubility of Oleic acid, copper salt is calculated as follows: Mean of concentration x 100 % / 9.6 %:

Vessel 3: 6.62 ± 0.22 mg/L

Vessel 4: 9.95 ± 0.23 mg/L

Vessel 5: 8.42 ± 0.30 mg/L

Mean: 8.33 ± 1 .40 mg/L

The measured dissolved copper concentrations in test item solution vary within vessels. This is probably due to the highly viscous, sticky test item. It cannot be guaranteed that the exposed surface area of the test item weight in at the beginning of testing is the same for each test vessel. As dissolution also depends on surface area this might be the reason.

Conclusions:

Under the conditions of this test (under exclusion of C02 and 02, under inert gas; flask method; loadings of ~100 mg/L test item in triplicate vessels a solubility equilibrium (difference in concentrations between two subsequent sampling points has to be less than 15 % and no observed increase of metal concentration) was observed after 36 days of testing. The mean measured content of dissolved copper at 20.0 ± 1.0 °C is 800 ± 135 μg/L (determined as dissolved copper on days 36, 37, 38, 42, 43, 44, separated by filtration (0.2 μm) from undissolved test item). This corresponds to a water solubility of oleic acid, copper salt of 8.33 ± 1 .40 mg/L, calculated on a copper content of 9.6 %.
The pH of test item solutions ranged between 5.2 and 5.9 whereas the pH of method blanks remained within 6.9 and 7.7.

Description of key information

Oleic acid, copper salt has a water solubility of 8.33 mg/L at 20 °C.

Key value for chemical safety assessment

Water solubility:

8.33 mg/L

at the temperature of:

20 °C

Additional information

Under the conditions of this test (under exclusion of C02 and 02, under inert gas; flask method; loadings of ~100 mg/L test item in triplicate vessels a solubility equilibrium (difference in concentrations between two subsequent sampling points has to be less than 15 % and no observed increase of metal concentration) was observed after 36 days of testing. The mean measured content of dissolved copper at 20.0 ± 1.0 °C is 800 ± 135 μg/L (determined as dissolved copper on days 36, 37, 38, 42, 43, 44, separated by filtration (0.2 μm) from undissolved test item). This corresponds to a water solubility of oleic acid, copper salt of 8.33 ± 1 .40 mg/L, calculated on a copper content of 9.6 %.

The pH of test item solutions ranged between 5.2 and 5.9 whereas the pH of method blanks remained within 6.9 and 7.7.