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Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

3rd May and 13th May 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: December 2002; Date of certificate: February 2003

Type of method:

flask method

Key result

Water solubility:

3.1 mg/L

Temp.:

20 °C

pH:

6.3 - 6.4

Details on results:

The preliminary results indicated that the test material was essentially insoluble in water and that the loading rate had no influence on the final analysed TOC concentration. Therefore the definitive test was performed at a single loading rate only, that of 1.0 g/l.

Preliminary test:

The preliminary results indicated that the test material was essentially insoluble in water and that the loading rate had no influence on the final analysed TOC concentration. Therefore the definitive test was performed at a single loading rate only, that of 1.0 g/l.

Definitive test

The TOC concentrations (mg/l) of the sample solutions are shown in the following table:

Solution	Total Organic Carbon Content (TOC in mg/l)
Sample 1A	3.7
Sample 1B	4.4
Sample 2A	1.4
Sample 2B	1.7
Sample 3A	3.1
Sample 3B	3.5
Water blank	0.6

As the water blank represented a significant contribution towards each sample TOC content, it has been subtracted from the definitive test overall results.

The results and sample treatment summary are shown in the following table:

Sample Number	Time Shaken at ~ 30ºC (hours)	Time Equilibrated at 20ºC (hours)	TOC Content (g/l)	Solution pH
1	24	24	3.5 x 10^-3	6.4
2	48	24	<1.0 x 10^-3	6.2
3	72	24	2.7 x 10^-3	6.3

Mean concentration:    3.1 x 10^-3 g/l at 20.0 ± 0.5 ºC (not including Sample 2, which was below the limit of quantification applied to the procedure)

Range:                         <1.0 x 10^-3 to 3.5 x 10^-3 g/l

Discussion:

Due to the test material being a very complex mixture of hydrocarbons, and it also being essentially insoluble in water, analysis of the sample solutions was performed monitoring the TOC content of the sample solutions only.

The preliminary water solubility test indicated that the column elution method should have been performed as the solubility was less than 1x10^-2 g/l. However, due to the physical nature of the test material, it was not possible to use this method; experience has shown that liquid test materials coated onto glass beads cause these beads to adhere together forming a plug within the column and thus preventing water circulation.

Conclusions:

The water solubility of the test material has been determined to be 3.1 mg TOC/l of solution at 20.0 ± 0.5°C.
Interpretation of results: slightly soluble (0.1-100 mg/L)

Executive summary:

The determination was carried out for 'Paraffin waxes (Fischer-Tropsch), full-range, C15-50 - branched and linear' using the flask method, Method A.6 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC).

Due to the test material being a very complex mixture of hydrocarbons, and it also being essentially insoluble in water, analysis of the sample solutions was performed monitoring the TOC content of the sample solutions only.

The preliminary water solubility test indicated that the column elution method should have been performed as the solubility was less than 1x10^-2g/l. However, due to the physical nature of the test material, it was not possible to use this method; experience has shown that liquid test materials coated onto glass beads cause these beads to adhere together forming a plug within the column and thus preventing water circulation.

The definitive test was based on the preliminary test. Mixtures of the test material and the glass double-distilled water were added to three seperate flasks. After addition of glass double-distilled water to the flasks, they were shaken at approximately 30 deg C and after standing at 20 deg C for a period of not less than 24 hours, the contents of the flasks were centrifuged at 13500 rpm for ca. 20 minutes. The pH of each solution was measured.

The water solubility of the test material was determined to be 3.1 x 10 ^-3 g TOC/l of solution at 20.0 +/- 0.5 deg C.

Description of key information

water solubility of the test material (determined using the flask method, EU Method A.6): 3.1 mg TOC/L at 20.0 ± 0.5°C (arithmetic mean of two determinations at pH 6.3 - 6.4)

Key value for chemical safety assessment

Water solubility:

3.1 mg/L

at the temperature of:

20 °C

Additional information

Although the preliminary test indicated that the column elution method should have been performed (as the solubility was less than 1x10E-02 g/L), due to the physical nature of the test material it was not possible to use this method. Experience has shown that liquid test materials coated onto glass beads cause these beads to adhere together forming a plug within the column and thus preventing water circulation.

Due to the test material being a complex mixture of hydrocarbons, and is also being essentially insoluble in water, analysis of the sample solution was performed monitoring the total organic carbon (TOC) content of the sample solutions only.

Predicted water solubility values, calculated using a validated QSAR method, are available for individual constituents of the registration substance. Predicted water solubility is in the range <1.0E-04 to 2.7E-04 mg/l.