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Physical & Chemical properties

Water solubility

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Reference
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2018-09-24 - 2018-10-24
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Version / remarks:
27 July 1995
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.6 (Water Solubility)
Version / remarks:
24 January 2014
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
flask method
Key result
Water solubility:
5.77 g/L
Conc. based on:
test mat.
Loading of aqueous phase:
25 g/L
Incubation duration:
7 d
Temp.:
20.3 °C
pH:
3.6
Details on results:
The measurements of the flasks 1A - 1C (days 7 - 9) and flasks 2 - 4 were included in the calculation of the mean as an upward tendency was observed on days 2 - 7. As no further increase was noted, it is assumed that a plateau is reached after 7 days.

All separated test solutions showed no Tyndall effect (i.e. a laser beam was not scattered when transmitted through the liquid). Interim pH measurements were made using pH paper; the final measurement was made using a calibrated pH-meter.

Conclusions:
The water solubility was determined to be 5.77 g/L.
Executive summary:

The solubility of the test item in water was determined by measurement of the test item concentration in the test solutions using GC/FID according to OECD guideline 105, EU method A.6 and under GLP conditions.

The preliminary test which is described in the guideline was performed in the method validation study 17111506G926. The solubility of the test item in water was estimated as 5 g/L (measured in a solution with a nominal load of the test item of 10 g/L). For test items with water solubility above 10 mg/L, the flask method is used. The test item solutions were stirred to speed up the solubility in water as a suspension was observed after shaking of the test item with water during the method validation study.

In the main test, 25 g/L Hexanal were used to prepare a saturated solution (in the guide¬lines, fivefold saturation is proposed). Six replicates were prepared (flasks 1A - C and 2 -4); three flasks 1A - C were used during the equilibration time. Four vessels (flasks 1C and 2 - 6) were set onto the stirrer at 29.7 - 30.2 °C (whole temperature range for 10 days; the flasks 1A - 1C were stirred for 3 days at 29.7 - 30.1 °C). After 24 ± 2 hours, flask 1B and after 48 ± 2 hours, flask 1A were set on the stirrer and all flasks were stirrer for further 24 ± 2 hours at 29.7 - 30.1 °C. Then, flasks 1A - 1C (corresponding to days 2 -4) were tempered at 20.1 - 20.5 °C for 25 hours, sampled, extracted and analysed via GC/FID. Because of an upward tendency, the test was prolonged and the flasks 1A - 1C were further stirred at 20.1 - 20.5 °C and sampled on days 4 - 9. Due to a difference of less than 15 % in the concentrations on days 8 and 9 and no upward tendency for the last three values, the test was finished. The flasks 2 - 4 were stirred at 29.7 - 30.2 °C for 10 days, than tempered at 20.1 - 20.3 °C for 24 hours and analysed.

The measurements of the flasks 1A - 1C (days 7 - 9) and flasks 2 - 4 were included in the calculation of the mean as an upward tendency was observed on days 2 - 7.

At the plateau (reached about the day 7), the concentration of Hexanal in water had reached: 5.77 ± 0.28 g/L at 20.3 ± 0.2 °C = 5.77 ± 0.28 kg/m3 (SI units) (mean value ± standard deviation of six individual vessels).

Description of key information

The solubility of the test item in water was determined by measurement of the test item concentration in the test solutions using GC/FID according to OECD guideline 105, EU method A.6 and under GLP conditions.

The preliminary test which is described in the guideline was performed in the method validation study 17111506G926. The solubility of the test item in water was estimated as 5 g/L (measured in a solution with a nominal load of the test item of 10 g/L). For test items with water solubility above 10 mg/L, the flask method is used. The test item solutions were stirred to speed up the solubility in water as a suspension was observed after shaking of the test item with water during the method validation study.

In the main test, 25 g/L Hexanal were used to prepare a saturated solution (in the guide¬lines, fivefold saturation is proposed). Six replicates were prepared (flasks 1A - C and 2 -4); three flasks 1A - C were used during the equilibration time. Four vessels (flasks 1C and 2 - 6) were set onto the stirrer at 29.7 - 30.2 °C (whole temperature range for 10 days; the flasks 1A - 1C were stirred for 3 days at 29.7 - 30.1 °C). After 24 ± 2 hours, flask 1B and after 48 ± 2 hours, flask 1A were set on the stirrer and all flasks were stirrer for further 24 ± 2 hours at 29.7 - 30.1 °C. Then, flasks 1A - 1C (corresponding to days 2 -4) were tempered at 20.1 - 20.5 °C for 25 hours, sampled, extracted and analysed via GC/FID. Because of an upward tendency, the test was prolonged and the flasks 1A - 1C were further stirred at 20.1 - 20.5 °C and sampled on days 4 - 9. Due to a difference of less than 15 % in the concentrations on days 8 and 9 and no upward tendency for the last three values, the test was finished. The flasks 2 - 4 were stirred at 29.7 - 30.2 °C for 10 days, than tempered at 20.1 - 20.3 °C for 24 hours and analysed.

The measurements of the flasks 1A - 1C (days 7 - 9) and flasks 2 - 4 were included in the calculation of the mean as an upward tendency was observed on days 2 - 7.

At the plateau (reached about the day 7), the concentration of Hexanal in water had reached: 5.77 ± 0.28 g/L at 20.3 ± 0.2 °C = 5.77 ± 0.28 kg/m3 (SI units) (mean value ± standard deviation of six individual vessels).

Key value for chemical safety assessment

Water solubility:
5.77 g/L
at the temperature of:
20.3 °C

Additional information

The result of the key study is supported by an other experimental study (no GLP, no guidline), handbook data and calculation:

Water solubility of hexanal was determined via gas chromatography. No guideline was followed and no GLP-conditions are considered. Water solubility of hexanal is 5.64 g/L at a temperature of 30 °C.

Water solubility of hexanal was described in several handbooks/puplications. Described properties are nearly the same: hexanal is slightly soluble in water. This is supported by one specific handbook value describing the water solubility of hexanal as 5 g/L at 25 °C and an accepted calculation method (based on an estimated Kow) which leads to a water solubility of 4.68 g/L at 25 °C.

Key Study: Davis, 1968:

Water solubility of hexanal was determined via gas chromatography. No guideline was followed and no GLP-conditions are considered. Water solubility of hexanal is 5.64 g/L at a temperature of 30 °C.

CRC Handbook:

Hexanal is slightly soluble in water.

Sax Dang. Prop.:

Hexanal is very slightly soluble in water.

Handbook of aqu. sol.:

5 g/L at 25 °C

EPI Suite calculation:

4.86 g/L at 25 °C

For the CSA the experimental derived value from the key study was chosen.