Zinc 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:

2012-03-26 to 2012-04-12

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 CO2 and O2; approx. 100 g of the test item was heated under argon to 100 °C in a water bath; 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; approx. 100 g of the test item was heated under argon to 100 °C in a water bath; 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:

>= 1.004 - <= 1.08 g/L

Temp.:

20 °C

pH:

>= 6.2 - <= 6.5

Remarks on result:

other: dissolved zinc on day 7- day 9 at a loading of 10 g/L

Water solubility:

>= 5.384 - <= 5.788 g/L

Temp.:

20 °C

pH:

>= 6.2 - <= 6.5

Remarks on result:

other: dissolved zinc 2-ethylhexanoate on day 7- day 9 at a loading of 10 g/L

Details on results:

Observations
During the study, undissolved test material was observed at the bottom of the flasks. After centrifugation and filtration, the solution was clear. In order to verify this, the turbidity was measured in the filtered samples

Temperature
The temperature in the thermostatically controlled water bath was monitored by a thermo datalogger. The mean temperature was 19.6 ± 0.7 °C.

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

pH values
At the beginning of the test pHs clearly decreased from 7.8 – 8.0 to 6.8 – 7.2. After the fourth sampling point pHs stabilized at 6.8 – 7.2. The temperature measured by the pH meter is not within 20.0 ± 1.0 °C. Considering the pH values the pH meter is calibrated every workweek and verified every working day. A calibration of the temperature was not performed because a reference thermometer were used during the test.

Turbidity measurements
The turbidity was measured after centrifugation and filtration to verify that only dissolved zinc concentrations would get measured. The turbidity was always <<1 NTU, indicating that no undissolved material was left after the filtration step.

ICP-OES measurement
Zinc levels of method blanks were always below the limit of detection (< 16 - < 35 µg/L). Constant zinc concentrations according to the study guideline OECD 105 as well as the Regulation 440/2008/EC A.6 were measured from day 7 until test end (day 9).

Constant zinc concentrations could be measured after 7 days (168 hours). The calculated variations between the last three sampling points were less than 15 %. Therefore, the study guideline OECD 105 as well as the Regulation 440/2008/EC A.6 could be regarded as fulfilled.

The mean concentration of day 7 (168 hours) until test end (day 9, 216 hours) was calculated.

Mean dissolved zinc concentration day 7 – day 9:

Vessel A: 1.041± 0.0377 g/L

Vessel B: 1.043 ± 0.0413 g/L

The calculated amount of zinc 2-ethylhexanoate dissolved was calculated by:  

= mean of measured values * 100 % / 18.65 % [percentage of zinc in test item]

 

mean calculated zinc 2-ethylhexanoate dissolved day 7 – day 9:

Vessel A: 5.581 ± 0.20 g/L

Vessel B: 5.591 ± 0.222 g/L

Under the conditions of this test (under exclusion of CO2and O2, under inert argon gas; flask method; loadings of 5.0005 g/ 500 mL in vessel A and B, respectively), a solubility equilibrium was reached after 7 days. The mean amountof dissolved zinc from day 7 until test end at 20.0 ± 1.0 °C is 1.042 ± 0.038 g/L (determined as dissolved zinc, separated by centrifugation and filtration from undissolved test item). This corresponds to calculated dissolved zinc 2-ethylhexanoate of 5.586 ± 0.202 g/L. The pHs in test vessels remained relatively constant during the test and ranged from 6.2 – 6.5.

Conclusions:

Interpretation of results: soluble (1000-10000 mg/L)
The test item zinc bis(2-ethylhexanoate) has a water solubility of 5.586 ± 0.202 g/L at 20 ± 1.0 °C and pH 6.2 – 6.5.

Description of key information

Zinc bis(2-ethylhexanoate) has a water solubility of 5.586 ± 0.202 g/L at 20 ± 1.0 °C and pH 6.2 – 6.5.

Key value for chemical safety assessment

Water solubility:

5.586 g/L

at the temperature of:

20 °C