2-ethylhexanoic acid, manganese 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 2013-04-24

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:

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

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

yes

Remarks:

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

GLP compliance:

yes (incl. QA statement)

Remarks:

2011-02-07

Type of method:

flask method

Remarks:

analysis via ICP-OES

Water solubility:

11.2 g/L

Conc. based on:

test mat.

Loading of aqueous phase:

50 g/L

Incubation duration:

32 d

Temp.:

20 °C

pH:

>= 5.5 - <= 6.1

Remarks on result:

other: calculated dissolved 2-ethylhexanoic acid, manganese salt from day 31 until day 32, at a loading of 50 g/L

Water solubility:

1.8 g/L

Conc. based on:

element

Remarks:

Mn

Loading of aqueous phase:

8.05 g/L

Incubation duration:

32 d

Temp.:

20 °C

pH:

>= 5.5 - <= 6.1

Remarks on result:

other: dissolved Mn from day 31 until day 32, at a loading of 50 g 2-ethylhexanoic acid, manganese salt /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 19.9 ± 0.3 °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 (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 test item containing vessels and method blanks ranged from 5.4 to 6.1. 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 Testo 175-T2 thermo data logger was applied during the test.

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. Method blanks were only filtered and not centrifuged, because the turbidity measurements were always < 1 NTU.

Dissolved manganese concentrations
Dissolved manganese concentrations in method blanks were at least below the respective limits of quantification (LOQ =0.595– 1.74 µg Mn/L) of respective measurement series.
Test samples were diluted (dilution factor 10,000) so that the respective Mn concentrations would be in the calibrated range of the ICP-OES instrument. Constant manganese concentrations as defined by the study guideline OECD 105 and the Regulation 440/2008/EC A.6 were measured from day 31 until day 32.

Method validation summary

validation parameter	results	comment
selectivity	similar data with three different manganese wavelengths for ICP-OES method	no interferences due to test media observed
linearity	applied calibration functions were linear	correlation coefficient at least 0.998530
limits of detection (LOD)	0.198– 0.385 µg Mn/L
limits of quantification (LOQ)	0.595 – 1.15 µg Mn/L
method blanks	at least below LOQ of respective measurement series LOQ = 0.595 – 1.74 µg Mn /L
accuracy and precision	mean recovery for CRM TM‑15.2 (18.1 µg Mn /L): 103 ± 2 % (n = 14)	for low concentration range
accuracy and precision	mean recovery for diluted CRM TM‑15.2 (9.05 µg Mn /L): 105 ± 6 % (n = 4)	for low concentration range
accuracy and precision	mean recovery for diluted CRM TMDA-70 (30.2 µg Mn /L): 105 ± 2 % (n = 18)	for concentration range
accuracy and precision	mean recovery for multielement standard solution XXI (100 µg Mn/L): 105 ± 2 % (n = 19)	for higher concentration range
accuracy and precision	mean recovery for multielement standard solution XXI (50 µg Mn/L): 106 ± 2 % (n = 5)	for concentration range
accuracy and precision	mean recovery for multielement standard solution XXI (10 µg Mn/L): 103 ± 1 % (n = 2)
trueness	recovery from fortification of samples: 102 – 105 % (n = 10)
repeatability	mean recovery for CRM TM‑15.2 (18.1 µg Mn /L): 103 ± 2 % (n = 14)	for low concentration range
repeatability	mean recovery for diluted CRM TMDA-70 (30.2 µg Mn /L): 105 ± 2 % (n = 18)	for concentration range
repeatability	mean recovery for multielement standard solution XXI (100 µg Mn/L): 105 ± 2 % (n = 19)	for higher concentration range
repeatability	mean recovery for multielement standard solution XXI (50 µg Mn/L): 106 ± 2 % (n = 5)	for concentration range

Constant manganese concentrations were measured from day 31 until day 32, i.e. manganese concentrations varied were less than 15 % between sampling points and no increase of the water solubility were observed. Thus, the validity criteria as foreseen in OECD 105 and Regulation 440/2008/EC A.6 were fulfilled. The mean dissolved manganese concentrations of solutions sampled from day 31 until day 32 were calculated.

Mean dissolved manganese concentrations day 31 – day 32:

Vessel 1: 1.6 ± 0.01 g Mn/L

Vessel 2: 2.0 ± 0.01 g Mn/L

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

 = mean of measured Mn concentration * 100 % / 16.1 % [Mn content of test item]

mean calculated manganese 2-ethylhexanoate dissolved day 31 – day 32:

Vessel 1: 9.9 ± 0.06 g/L

Vessel 2: 12.2 ± 0.06 g/L

Conclusion

Under the conditions of this test(under exclusion of CO2 and O2, under inert argon gas; flask method; loadings of and 50.0052 and 50.0164 g/L in vessel 1 and 2, respectively), a solubility equilibrium was reached from day 31 until day 32 of testing. The mean amount of dissolved Mn from day 31 until day 32 at 20.0 ± 1.0 °C is 1.8 ± 0.2 g/L (determined as dissolved Mn, separated by filtration from undissolved test item). This corresponds to a calculated water solubility of 2-ethylhexanoic acid, manganese salt of 11.2 ± 1.2 g/L, calculated based on a manganese content of 16.1 %. Solution pH in test item containing vessels and method blanks ranged from 5.5 to 6.1.

Conclusions:

Interpretation of results (migrated information): very soluble (> 10000 mg/L)
The test item 2-ethylhexanoic acid, manganese salt has a water solubility of 11.2 ± 1.2 g/L at 20.0 ± 1.0 °C, pH 5.5 to 6.1.

Description of key information

The test item 2-ethylhexanoic acid, manganese salt has a water solubility of up to 11.2 ± 1.2 g/L after 32 days at a loading of 50 g/L (20.0 ± 1.0 °C, pH 5.5 to 6.1).

Key value for chemical safety assessment

Water solubility:

11.2 g/L

at the temperature of:

20 °C