2-ethylhexanoic acid, zirconium 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:

2013-03-20 to 2013-04-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

, exclusion of CO2 and O2; 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.

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

yes

Remarks:

, exclusion of CO2 and O2; 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.

GLP compliance:

yes (incl. QA statement)

Remarks:

signed, 2011-02-07

Type of method:

flask method

Water solubility:

< 0.21 µg/L

Conc. based on:

element

Remarks:

zirconium

Loading of aqueous phase:

50 mg/L

Incubation duration:

3 d

Temp.:

20 °C

pH:

>= 4.8 - <= 5.1

Remarks on result:

other: dissolved zirconium from day 1 until day 3, at a loading of 50 mg 2-ethylhexanoic acid, zirconium salts/L

Water solubility:

< 0.75 µg/L

Conc. based on:

test mat.

Loading of aqueous phase:

50 mg/L

Incubation duration:

3 d

Temp.:

20 °C

pH:

>= 4.8 - <= 5.1

Remarks on result:

other: dissolved 2-ethylhexanoic acid, zirconium salts from day 1 until day 3, at a loading of 50 mg/L

Details on results:

Observations
During the study, undissolved test material was observed in the media in the flasks. After filtration and subsequent centrifugation, 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.

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 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 5.4 to 5.9, the pH in samples containing the test item was 4.8 – 5.1. The temperature measured by the pH meter is within 20.0 ± 1.0 °C.

Turbidity
The turbidity was measured after centrifugation and filtration to verify that only dissolved zirconium 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.

Dissolved zirconium concentrations
Dissolved zirconium concentrations in method blanks sampled at each time point were below the limit of detection (< 0.30 µg Zr/L) of respective measurement series. Zirconium concentrations in all actual test samples were also below the limit of detection (< 0.21 µg Zr/L) of respective measurement series.

Method validation summary

validation parameter	results	comment
selectivity	similar data with at least two different zirconium wavelengths for ICP-OES method	no matrix effects observed
linearity	applied calibration functions were linear	correlation coefficient at least 0.9991
limits of detection (LOD)	0.210 – 0.295 µg Zr/L
limits of quantification (LOQ)	0.629 – 0.884 µg Zr/L
method blanks	below LOD (< 0.21 µg Zr/L)
accuracy and precision	mean recovery for Merck Zr standard (10 µg Zr /L): 103 ± 4 % (n = 6)	for concentration range
accuracy and precision	mean recovery for Merck Zr standard (50 µg Zr /L): 106 ± 1 % (n = 4)	for higher concentration range
accuracy and precision	mean recovery for Merck Zr standard (100 µg Zr /L): 102 ± 2 % (n = 6)	for high concentration range
accuracy and precision	recovery from fortification of samples / recalibration samples: 103 – 106 %
repeatability	mean recovery for Merck Zr standard (10 µg Zr /L): 103 ± 4 % (n = 6)	for concentration range
repeatability	mean recovery for Merck Zr standard (50 µg Zr /L): 106 ± 1 % (n = 4)	for higher concentration range
repeatability	mean recovery for Merck Zr standard (100 µg Zr /L): 102 ± 2 % (n = 6)	for high concentration range

Results

During day 1, day 2 and day 3 of testing zirconium concentrations in test samples were always < 0.210 µg/L, i.e. the limit of detection (LOD) of respective ICP-OES measurement series. Therefore, a limit test up to the detection limit of the analytical method is sufficient according to regulation (EC) 1907/2006, Annex VII, point 7.7.

The amount of 2-ethylhexanoic acid, zirconium salt dissolved was calculated based on the zirconium content of the test substance as follows:

 = Zr concentration (< 0.21 µg/L) * 100 % / 28 %

mean calculated 2-ethylhexanoic acid, zirconium salt dissolved day 1 – day 3: 

< 0.75 µg test item /L

Conclusion

Under the conditions of this test (under exclusion of CO2 and O2, under inert argon gas; flask method; loadings of 50.02 and 50.04 mg/L in vessel 1 and 2, respectively), the amount of dissolved Zr from day 1 until day 3 at 20.0 ± 1.0°C is < 0.21 µg/L (determined as dissolved Zr, separated by filtration). The water solubility of zirconium is below the limit of detection of the respective analytical method (ICP-OES). This corresponds to a calculated water solubility of dissolved 2-ethylhexanoic acid, zirconium salts of < 0.75 µg/L, calculated based on a zirconium content of 28 %. Solution pH in method blanks ranged from 5.4 to 5.9, the pH in samples containing the test item was 4.8 – 5.1.

 

Conclusions:

Interpretation of results (migrated information): insoluble (< 0.1 mg/L)
The water solubility of dissolved 2-ethylhexanoic acid, zirconium salts is < 0.75 µg/L at 20.0 ± 1.0 °C and pH 4.8 – 5.1.

Description of key information

The water solubility of dissolved 2-ethylhexanoic acid, zirconium salts is < 0.75 µg/L at 20.0 ± 1.0 °C and pH 4.8 – 5.1.