Resin acids and Rosin acids, cobalt 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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

please refer to the field "Principle of method if other than guideline"

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

yes

Remarks:

please refer to the field "Principle of method if other than guideline"

Principles of method if other than guideline:

- Test was conducted under exclusion of carbon dioxide and oxygen, to avoid oxidative degradation of the organic anion.
- Two vessels were set up in a parallel design at 20 ± 1.0 °C, each vessel was sampled several times instead of sampling one vessel at every point in time, to reduce the weighing error.

GLP compliance:

yes (incl. QA statement)

Remarks:

2011-02-07

Type of method:

flask method

Water solubility:

>= 27.06 - <= 30 mg/L

Temp.:

20 °C

pH:

>= 6.4 - <= 6.7

Remarks on result:

other: dissolved cobalt resinate

Water solubility:

>= 1.96 - <= 2.532 mg/L

Temp.:

20 °C

pH:

>= 6.4 - <= 6.7

Remarks on result:

other: dissolved Co

Details on results:

Under the conditions of this test (under exclusion of CO2 and O2, under inert argon gas; flask method; loadings of 350.6 g/L in vessel A and B, respectively), a solubility equilibrium was reached during the three days of testing (days 3 – 5). The mean amount of dissolved cobalt during the test at 20.0 ± 1.0°C is 2.246 ± 0.286 mg/L (determined as dissolved Co, separated by filtration from undissolved test item). This corresponds to dissolved cobalt resinate of 28.08 ± 1.02 mg/L. After adding the test substance the pH in the respective vessels decreased slightly from 6.9 to 6.2 in vessel A and from 6.6 to 6.1 in vessel B. Measured pH blank samples were between 6.4 and 6.7.

Method validation summary

Validation parameter	results	comment
selectivity	similar data with three different cobalt wavelengths for ICP-OES method	no matrix effects observed
linearity	applied calibration functions were linear	correlation coefficient at least 0.9992
limit of detection (LOD)	20 - 25 µg Co/L
limits of quantification (LOQ)	66 - 83 µg Co/L
method blanks	below LOD (< 25 µg Co/L)	-
accuracy and precision	mean recovery for TMDA-70: 97.5 ± 0.8 % (n = 7)	corresponds to concentration range of diluted samples (285 µg Co/L)
accuracy and precision	mean recovery for CPI quality control standard: 96.3 ± 1.0 % (n = 5)	corresponds to concentration range (250 µg Co/L)
accuracy and precision	mean recovery for CPI quality control standard: 98.6 ± 0.4 % (n = 2)	corresponds to higher concentration range (500 µg Co/L)
accuracy and precision	mean recovery for recalibration standards: 94.6 ± 1.1 % (n = 3)	corresponds to lower concentration range (100 µg Co/L)
repeatability	recovery from fortification of samples: 99.3 – 101 % (n=4)
reproducibility	mean recovery for TMDA-70: 97.5 ± 0.8 % (n = 7)	corresponds to concentration range of diluted samples (285 µg Co/L)
reproducibility	mean recovery for CPI quality control standard: 96.3 ± 1.0 % (n = 5)	corresponds to concentration range (250 µg Co/L)

Measured cobalt concentrations in test samples

stirring time [d]	Co conc. of samples vessel A [mg/L]	mean Co conc. ± SD vessel A [mg/L]	Co conc. of samples vessel B [mg/L]	mean Co conc. ± SD vessel B [mg/L]	mean Co conc. ± SD [mg/L]	variation between samplings [%]
3	1.684	1.694 ± 0.014	2.342	2.342 ± < 0.001	2.018 ± 0.374	-
	1.704		2.342
4	2.137	2.146 ± 0.013	2.478	2.491 ± 0.018	2.318 ± 0.199	14.9
	2.155		2.503
5	2.297	2.312 ± 0.021	2.487	2.495 ± 0.011	2.403 ± 0.106	3.7
	2.326		2.502

The shaking flask vessels were set up in duplicate. Samples were taken after 3 (72), 4 (96), and 5 days (120 hours). The pH was measured in the test vessels and Co concentrations as well as the turbidity were determined in samples after filtration. After adding the test substance the pH in the respective vessels decreased slightly from 6.9 to 6.2 in vessel A and from 6.6 to 6.1 in vessel B. Measured pH in blank samples were between 6.4 and 6.7. The oxygen concentration inside the experimental setup remained around 0 %.

Co analysis was carried out via ICP-OES. The samples were measured in duplicate. Based on previous test results 175 mg of the test substance was added into 500 mL of argon saturated water under argon atmosphere (175.3 mg/500 mL were weighed into vessel A and B, respectively). This loading corresponded to approx. five to ten times the quantity of the dissolved test item as determined in the previous test. Furthermore insoluble residues in the test vessels were observed throughout the test.

Constant Co concentrations could be measured during the test between days 3 and 5. The variations between the three sampling points were less than 15 %. Thus, the validity criteria as foreseen in OECD TG 105 and Regulation 440/2008/EC A.6 were fulfilled.

The mean dissolved cobalt concentration between day 3 and day 5 are as follows:
Vessel A:  2.051± 0.286 mg/L
Vessel B: 2.442 ± 0.078 mg/L

The calculated amount of cobalt resinate dissolved was calculated by:

 = mean of measured values * 100 % / 8.0 % [percentage of Co in test item]

mean calculated cobalt resinate dissolved day 3 – day 5:

Vessel A: 25.63 ± 1.12 mg/L
Vessel B: 30.53 ± 0.26 mg/L

Conclusions:

Interpretation of results: slightly soluble (0.1-100 mg/L)
Under the conditions of this test (under exclusion of CO2 and O2, under inert argon gas; flask method; loadings of 350.6 g/L in vessel A and B, respectively), a solubility equilibrium was reached during the three days of testing (days 3 – 5) the water solubility of cobalt resinate is 28.08 ± 1.02 mg/L at pH 6.4 - 6.7.

Reference 2

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-07-30 to 2009-08-18

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:

no

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

, 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2008-11-12

Type of method:

flask method

Water solubility:

33.53 mg/L

Temp.:

20 °C

pH:

ca. 6.79

Water solubility:

272.89 mg/L

Temp.:

37 °C

pH:

ca. 6.58

Details on results:

During this study the water solubility of cobalt resinate at 20 °C and at 37 °C was determined using the flask method and was found to be 33.53 mg/L at 20 °C (after 120 hours of shaking) based on a measured concentration of 2.57 mg Co/L and 272.89 mg/L at 37 °C (after 120 hours of shaking) based on a measured concentration of 20.88 mg Co/L.

Conclusions:

Interpretation of results: slightly soluble (0.1-100 mg/L)
During this study the water solubility of cobalt resinate at 20 °C and at 37 °C was determined using the flask method and was found to be 33.53 mg/L at 20 °C based on a measured concentration of 2.57 mg Co/L and 272.89 mg/L at 37 °C based on a measured concentration of 20.88 mg Co/L.

Description of key information

Water solubility of resin acids and rosin acids, cobalt salts : 33.53 mg/L at 20 °C, 272.89 mg/L at 37 °C (under oxic atmosphere) and 28.1mg/L (at 20°C under inert gas atmosphere).

Key value for chemical safety assessment

Water solubility:

33.53 mg/L

at the temperature of:

20 °C

Additional information

In Tobler (2009) the water solubility of resin acids and rosin acids, cobalt salts was determined according to OECD guideline 105 with the flask method. During this study the water solubility of the test item was found to be 33.53 mg/L at 20 °C (after 120 hours of shaking) based on a measured concentration of 2.57 mg Co/L and 272.89 mg/L at 37 °C (after 120 hours of shaking) based on a measured concentration of 20.88 mg Co/L.

To assess whether the oxic atmosphere interferes with the water solubility testing a second experiment was conducted under inert gas atmosphere. In Klawonn (2012) a solubility equilibrium was reached during the three days of testing (days 3 – 5) the water solubility of cobalt resinate is 28.08 ± 1.02 mg/L at pH 6.4 - 6.7.