Calcium bis(2-ethylhexanoate)

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013-04-04 to 2013-04-10

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:

, exclusion of O2 and Co2; two vessesls were set up in a parallel design, each solution was sampled several times instead of setting up multiple vessels and sampling solutions from different vessels at each sampling date

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

yes

Remarks:

, exclusion of O2 and Co2; two vessesls were set up in a parallel design, each solution was sampled several times instead of setting up multiple vessels and sampling solutions from different vessels at each sampling date

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2011-02-07

Type of method:

flask method

Water solubility:

8.359 g/L

Conc. based on:

element (dissolved fraction)

Remarks:

Ca

Loading of aqueous phase:

300 g/L

Incubation duration:

3 d

Temp.:

20 °C

pH:

>= 6.9 - <= 7.3

Remarks on result:

other: dissolved calcium from day 1 until day 3 at a loading of ca. 300 g calcium bis(2-ethylhexanoate) /L

Water solubility:

80.4 g/L

Conc. based on:

test mat. (dissolved fraction)

Loading of aqueous phase:

300 g/L

Incubation duration:

3 d

Temp.:

20 °C

pH:

>= 6.9 - <= 7.3

Remarks on result:

other: calculated calcium bis(2-ethylhexanoate) from day 1 until day 3 at a loading of ca. 300 g/L

Details on results:

Observations
During the study, undissolved test material was observed in the media in the flasks. After filtration, the solutions were clear. In order to verify this, the turbidity was measured in filtered samples.

Temperature
The temperature in the thermostatically controlled water bath was monitored by a Testo 175-T2 thermo datalogger. The mean temperature was 20.5 ± 0.1 °C.
 
Temperature monitoring with the respective datalogger is still ongoing, because further metal(soaps) for EBRC are still under investigation.

Monitoring oxygen concentration
During the experimental performance of the test, the oxygen concentration in the acrylic glass box was monitored with a MICRO IV oxygen sensor prior and after sampling. The oxygen values (in %) remained around 0 %. Slightly negative values, though impossible, are due to measurement uncertainties of the device at 0 % oxygen.

Solution pH
Solution pH in method blanks ranged from 5.2 to 5.6, whereas the pH in samples containing the test item ranged from 6.8 – 6.9.

Turbidity
The turbidity was measured after centrifugation and filtration to verify that only dissolved calcium concentrations would get measured. The turbidity was always < 1 NTU, indicating that there was not any undissolved material and micelles did not form after the filtration and centrifugation step. Turbidity data are compiled inTable6andTable7. Method blanks were only filtered and not centrifuged, because the turbidity measurements were always < 1 NTU

Dissolved calcium concentrations
Dissolved calcium concentrations in all method blanks (19.92 – 70.36 µg Ca/ L) sampled at each sampling point were always clearly above the respective limit of quantification LOQ = 1.07 µg Ca/ L). However, compared to concentrations in test item loaded samples the Ca amount in method blanks is << 0.1 %. Alternating concentrations from day 1 to day 3 were observed. Thus, this is not due to contamination of the electrode (used for pH-measurement). In fact, the reason might be a contamination during sampling due to ubiquitous calcium.
Test samples were diluted (dilution factor 10,000) so that the respective Ca concentrations would be in the calibrated range of the ICP-OES instrument. Constant calcium concentrations as defined by the study guideline OECD 105 and the Regulation 440/2008/EC A.6 were measured from day 1 until day 3.

Method validation summary

validation parameter	results	comment
selectivity	similar data with at least two different calcium wavelengths for ICP-OES method	no interferences due to test media observed
linearity	applied calibration functions were linear	correlation coefficient at least 0.999869
limits of detection (LOD)	0.116– 0.358 µg Ca/L
limits of quantification (LOQ)	0.348 – 1.07 µg Ca/L
method blanks	above LOQ but far below conc. in actual samples (<< 0.1%)
accuracy and precision	Mean recovery for quality control (100 µg Ca/L): 103 ± 2 (n = 8)	for concentration range of diluted samples
accuracy and precision	Mean recovery for recalibration (500 µg Ca/L): 100 ± 1 (n = 7)	for concentration range of diluted samples
trueness	recovery from fortification of samples: 96.5 – 98.4 %

Results

Constant calcium concentrations were measured from day 1 until day 3, i.e. calcium concentrations varied were less than 15 % between sampling points. Therefore, the acceptability criteria of the study guideline OECD 105 and the Regulation 440/2008/EC A.6 could be regarded as fulfilled.

The mean dissolved calcium concentrations of solutions sampled from day 1 until day 3 were calculated.

Mean dissolved Ca concentrations day 1 – day 3:

Vessel 1: 7.990 ± 0.351 g Ca/L

Vessel 2: 8.728 ± 0.208 g Ca/L

The amount of calcium isononanoate dissolved was calculated based on the metal content of the test substance as follows:

 = mean of measured Ca concentration * 100 % / 10.4 % [Ca content of test item]

mean calculated calcium isononanoate dissolved day 1 – day 3:

Vessel 1: 76.83 ± 3.38 g/L

Vessel 2: 83.92 ± 2.00 g/L

Conclusion

Under the conditions of this test (under exclusion of CO2 and O2, under inert argon gas; flask method; loadings of and 300.082 and 300.2988 g/L in vessel 1 and 2, respectively), a solubility equilibrium was reached from day 1 until day 3 of testing. The mean amount of dissolved Ca from day 1 until day 3 at 20.0 ± 1.0 °C is 8.359 ± 0.474 g/L (determined as dissolved Ca, separated by from undissolved test item). This corresponds to a calculated water solubility of calcium bis(2-ethylhexanoate) of 80.4 ± 4.6 g/L, calculated based on a calcium content of 10.4 %. Solution pH in method blanks ranged from 5.2 to 5.6, whereas the pH in samples containing the test item ranged from 6.8 – 6.9.

Conclusions:

Interpretation of results: very soluble (> 10000 mg/L)
The water solubility of the test item calcium bis(2-ethylhexanoate) from day 1 until day 3 of testing is 80.4 ± 4.6 g/L at 20.0 ± 1.0 °C and pH 6.8 – 6.9.

Description of key information

The water solubility of the test item calcium bis(2-ethylhexanoate) from day 1 until day 3 of testing is 80.4 ± 4.6 g/L at 20.0 ± 1.0 °C and pH 6.8 – 6.9.

Key value for chemical safety assessment

Water solubility:

80.4 g/L

at the temperature of:

20 °C

Additional information

The dissolution of calcium from Calcium bis (2-ethylhexanoate) after 2h in simulated gastric acid (pH 1.5) at 0.2 and 2 g/L loading is 90 and 91%, respectively, corresponding to 21.7 and 217 mg Ca/L (ECTX, 2022).