Hydrocarbons, C15-C19, n-alkanes, isoalkanes,

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experimental Starting Date: 10 July 2014 Experimental Completion Date: 25 October 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

other:

Deviations:

no

Principles of method if other than guideline:

The determination was carried out using a slow stir adaptation of the standard test method, based on the findings of Letinski, D.J., Connolly, M.J., Peterson, D.R. and Parkerton, T.F. (2002) “Slow-stir water solubility measurements of selected alcohols and diesters”, Chemosphere 48, 257-265. The method employed was designed to be compatible with the data endpoint requirements of Method A6 Water Solubility of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 105 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.

GLP compliance:

yes

Type of method:

other: slow-stir adaptation of standard method

Key result

Water solubility:

< 0 g/L

Temp.:

20 °C

Remarks on result:

other: Initial Nominal Loading Rate of 100 mg/L

Key result

Water solubility:

< 0 g/L

Temp.:

20 °C

Remarks on result:

other: Initial Nominal Loading Rate of 10 mg/L

Results

Main Test

The mean peak area ratios relating to the standard, sample and blank solutions are shown in the following tables:

 

Table 3.1– Nominal 100 mg/L Loading Rate

Solution	Mean Peak AreaRatio
Standard 12.3 mg/L	1.1025
Standard 12.5 mg/L	1.1377
Vessel 1 Sample 1	0.094700
Vessel 2 Sample 1	0.070662
Vessel 3 Sample 1	0.034166
Sample Blank	0.028235
Standard 12.0 mg/L	1.1359
Standard 11.6 mg/L	1.0828
Vessel 1 Sample 2	0.12385
Vessel 1 Sample 3	0.045714
Vessel 2 Sample 2	0.086710
Vessel 2 Sample 3	0.041093
Vessel 3 Sample 2	0.034924
Vessel 3 Sample 3	0.044094
Sample Blank	0.031124
Standard 10.7 mg/L	0.94819
Standard 11.8 mg/L	1.0050
Vessel 1 Sample 4	0.18342
Vessel 1 Sample 5	0.031441
Vessel 2 Sample 4	0.043331
Vessel 2 Sample 5	0.10310
Vessel 3 Sample 4	0.037796
Vessel 3 Sample 5	0.033121
Sample Blank	0.098785

 

Table 3.1– Nominal 100 mg/L Loading Rate - Continued

Solution	Mean Peak Area Ratio
Standard 10.4 mg/L	0.90695
Standard 11.1 mg/L	0.96049
Vessel 1 Sample 6	0.029381
Vessel 2 Sample 6	0.020824
Vessel 3 Sample 6	0.031843
Sample Blank	0.11007

 

Table 3.2– Nominal 10 mg/L Loading Rate

Solution	Mean Peak Area Ratio
Standard 12.3 mg/L	1.1025
Standard 12.5 mg/L	1.1377
Vessel 1 Sample 1	0.083834
Vessel 2 Sample 1	0.032294
Vessel 3 Sample 1	0.027888
Sample Blank	0.028235
Standard 12.0 mg/L	1.0961
Standard 11.6 mg/L	1.0333
Vessel 1 Sample 2	0.040130
Vessel 1 Sample 3	0.059563
Vessel 2 Sample 2	0.036098
Vessel 2 Sample 3	0.035493
Vessel 3 Sample 2	0.031781
Vessel 3 Sample 3	0.042231
Sample Blank	0.031124

 

 

  Table 3.2– Nominal 10 mg/L Loading Rate - Continued

Solution	Mean Peak Area Ratio
Standard 10.7 mg/L	0.92765
Standard 11.8 mg/L	1.0013
Vessel 1 Sample 4	0.063203
Vessel 1 Sample 5	0.023069
Vessel 2 Sample 4	0.037548
Vessel 2 Sample 5	0.020285
Vessel 3 Sample 4	0.039763
Vessel 3 Sample 5	0.022421
Sample Blank	0.098785
Standard 10.4 mg/L	0.90695
Standard 11.1 mg/L	0.96049
Vessel 1 Sample 6	0.058427
Vessel 2 Sample 6	0.025485
Vessel 3 Sample 6	0.020424
Sample Blank	0.11007

 

As the test item peaks covered a wide retention time range and there were peaks observed in the blank solutions over the same range, the concentration attributed to the blank was subtracted from the sample concentrations. 

 

The concentration (g/L) of test item in the sample solutions corrected for blank response is shown in the following tables:

 

Table 3.3– Nominal 100 mg/L Loading Rate, Vessel 1

Sample Number	Stirring / Equilibration Time (hours)	Concentration (g/L)	Solution pH
1	22.8	7.37 x 10^-6	6.90
2	44.1	9.85 x 10^-6	7.04
3	49.8	1.55 x 10^-6	6.70
4	68.2	9.73 x 10^-6	7.00
5	73.7	-7.75 x 10^-6	7.00
6	92.3	-9.28 x 10^-6	7.10

 

A variable, negligible quantity was detected in the retention time range of the test item in both samples and sample blank. The amount detected was well below the range investigated for the analysis. The result is therefore taken as less than the level at which successful detection of the test item was achieved. See validation and discussion in overall remarks and attachments section below.

 

Table 3.4– Nominal 100 mg/L Loading Rate, Vessel 2

Sample Number	Stirring / Equilibration Time (hours)	Concentration (g/L)	Solution pH
1	22.8	4.70 x 10^-6	6.99
2	44.1	5.91 x 10^-6	7.05
3	49.8	1.06 x 10^-6	6.74
4	68.2	-6.38 x 10^-6	6.74
5	73.7	4.96 x 10^-7	6.81
6	92.3	-1.03 x 10^-5	7.04

 

A variable, negligible quantity was detected in the retention time range of the test item in both samples and sample blank. The amount detected was well below the range investigated for the analysis. The result is therefore taken as less than the level at which successful detection of the test item was achieved.  See validation and discussion in overall remarks and attachments section below.

 

 

Table 3.5– Nominal 100 mg/L Loading Rate, Vessel 3

Sample Number	Stirring / Equilibration Time (hours)	Concentration (g/L)	Solution pH
1	22.8	6.58 x 10^-7	6.94
2	44.1	1.06 x 10^-6	6.92
3	49.8	4.04 x 10^-7	6.89
4	68.2	-7.01 x 10^-6	6.88
5	73.7	-7.55 x 10^-6	6.74
6	92.3	-9.00 x 10^-6	6.99

 

A variable, negligible quantity was detected in the retention time range of the test item in both samples and sample blank. The amount detected was well below the range investigated for the analysis. The result is therefore taken as less than the level at which successful detection of the test item was achieved.  See validation and discussion in overall remarks and attachments section below.

 

Table3.6– Nominal 10 mg/L Loading Rate, Vessel 1

Sample Number	Stirring / Equilibration Time (hours)	Concentration (g/L)	Solution pH
1	22.8	6.17 x 10^-6	7.00
2	44.1	1.14 x 10^-6	7.10
3	49.8	3.29 x 10^-6	6.80
4	68.2	-4.00 x 10^-6	6.69
5	73.7	-8.67 x 10^-6	6.92
6	92.3	-5.94 x 10^-6	7.06

 

A variable, negligible quantity was detected in the retention time range of the test item in both samples and sample blank. The amount detected was well below the range investigated for the analysis. The result is therefore taken as less than the level at which successful detection of the test item was achieved. See validation and discussion in overall remarks and attachments section below.

 

 

Table3.7– Nominal 10 mg/L Loading Rate, Vessel 2

Sample Number	Stirring / Equilibration Time (hours)	Concentration (g/L)	Solution pH
1	22.8	4.50 x 10^-7	7.09
2	44.1	6.90 x 10^-7	6.99
3	49.8	6.23 x 10^-7	6.71
4	68.2	-6.99 x 10^-6	6.91
5	73.7	-9.00 x 10^-6	6.84
6	92.3	-9.73 x 10^-6	6.88

 

A variable, negligible quantity was detected in the retention time range of the test item in both samples and sample blank. The amount detected was well below the range investigated for the analysis. The result is therefore taken as less than the level at which successful detection of the test item was achieved. See validation and discussion in overall remarks and attachments section below.

 

Table3.8– Nominal 10 mg/L Loading Rate, Vessel 3

Sample Number	Stirring / Equilibration Time (hours)	Concentration (g/L)	Solution pH
1	22.8	-3.85 x 10^-8	6.81
2	44.1	2.12 x 10^-7	6.91
3	49.8	1.37 x 10^-6	6.81
4	68.2	-6.73 x 10^-6	6.99
5	73.7	-8.75 x 10^-6	6.90
6	92.3	-1.03 x 10^-5	6.95

 

A variable, negligible quantity was detected in the retention time range of the test item in both samples and sample blank. The amount detected was well below the range investigated for the analysis. The result is therefore taken as less than the level at which successful detection of the test item was achieved. See validation and discussion in overall remarks and attachments section below.

 

 

The overall water solubility results for the two different loading rates evaluated are summarized in the following tables:

 

Table 3.9– Nominal 100 mg/L Loading Rate

Vessel	1	2	3
Mean Water Solubility (g/L at 20.0 ± 0.5 ºC)	< 1.15x 10^-4	< 1.15x 10^-4	< 1.15x 10^-4
Standard Deviation	not applicable	not applicable	not applicable
Relative Standard Deviation	not applicable	not applicable	not applicable

 

Overallwater solubility                             :         less than 1.15x 10^-4g/L at 20.0 ± 0.5 ºC

 

Table3.10– Nominal 10 mg/L Loading Rate

Vessel	1	2	3
Mean Water Solubility (g/L at 20.0 ± 0.5 ºC)	< 1.15x 10^-4	< 1.15x 10^-4	< 1.15x 10^-4
Standard Deviation	not applicable	not applicable	not applicable
Relative Standard Deviation	not applicable	not applicable	not applicable

 

Overall water solubility                             :         less than 1.15x 10^-4g/L at 20.0 ± 0.5 ºC

Conclusions:

Please see the Conclusion within the Executive Summary Section below.

Executive summary:

The determination was carried out using a slow stiradaptation of the standard test method, based on thefindings of Letinski, D.J., Connolly, M.J., Peterson, D.R. and Parkerton, T.F. (2002) “Slow-stir water solubility measurements of selected alcohols and diesters”, Chemosphere 48, 257-265. The method employed was designedto be compatible with the data endpoint requirements of Method A6 Water Solubility of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 105 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.

 

The slow-stir procedure was used as during a previous study (Harlan Study Number 41304207) using the flask method, it was identified that excess, undissolved test item could not be successfully excluded from the saturated solutions. The slow stir method eliminated dispersion of the test item throughout the solution and thus allowed isolation of saturated solutions free from excess, undissolved test item suitable for analysis.

 

Slow-stirring therefore enables the solubilisation of the test item without the formation of potentially problematic micro-droplets. The alternative column elution method proposed by the guidelines for addressing substances of low solubility is poorly suited to liquid test items.

 

As the test item is a UVCB substance, the effect of initial loading rate was also evaluated during the definitive determination of water solubility, using initial nominal loading rates of 100 mg/L and 10 mg/L, in order to assess if this affected either the resulting aqueous concentration or the composition of the dissolved fraction.

Conclusion

The water solubility of the test item at 20.0 ± 0.5 °C was evaluated using a slow stir adaptation of the standard test method. The results are summarized in the following table:

 

Table3.11

Initial Nominal Loading Rate	Water Solubility  (g/L of solution at 20.0 ± 0.5 °C)
100 mg/L	< 1.15x 10^-4
10 mg/L	< 1.15x 10^-4

 

Description of key information

Water solubility (whole substance): <0.1 m/l at 20±0.5°C (measured).

Water solubility (individual constituents): <1E-04 - 1.1E-03 mg/l at 20°C (QSAR).

Additional information

The substance is a hydrocarbon UVCB and the constituent hydrocarbons will exhibit a wide range of water solubility. Standard tests for this endpoint are intended for single substances and are not appropriate for this complex substance as the composition of the total dissolved hydrocarbons will be different from the composition of the parent substance. However, this endpoint can be characterised using quantitative structure property relationships for representative hydrocarbon structures that comprise the hydrocarbon blocks used to assess the environmental risk of this substance with the PETRORISK model (see Product Library in PETRORISK spreadsheet attached in Section 13).

The "whole substance" water solubility of Hydrocarbons, C15-C19, n-alkanes, isoalkanes, <2% aromatics was evaluated using a slow-stir method (Tarran 2015). The method was designed to be compatible with EU Method A.6 and OECD 105. Since the submission substance is a UVCB, the effect of initial loading rate was also evaluated during the definitive study using initial nominal loading rates of 100 mg/l and 10 mg/l to assess if the resulting aqueous concentration or the composition of the dissolved fraction were affected. The water solubility of Hydrocarbons, C15-C19, n-alkanes, isoalkanes, <2% aromatics was determined to be <0.1 m/l at 20±0.5°C in both the 100 mg/l and 10 mg/l loading rates.

As supporting information, the water solubility of each constituent has also been predicted using a separately validated QSAR estimation method. The prediction method uses a fragment method and water solubility decreases with increasing carbon number. The prediction domain covers carbon chain length in the range C2-C15 carbon atom, it is therefore expected that water solubility for longer chain length (i.e. greater than C15) compounds will be lower than the predicted value for C15 atom. Thus, the water solubility of the individual constituents is in the range <1E-04 - 1.1E-03 mg/l.