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Physical & Chemical properties

Water solubility

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From Study KY090009 water solubility was determined using the flask method, Method A6 of Commission regulation (EC) No 44012008 of 30 May 2008 for the following individual chain lengths of the test item: 1) sodium octanoyl isethionate (C8); 2) sodium lauroyl isethionate (C12); 3) sodium myristoyl isethionate (C14); 4) sodium palmitoyl isethionate (C16); and 5) sodium stearoyl isethionate (C18).  
The reason that single chain length water solubilities were determined in study KY090009 is that data obtained on the registered substance (multi-constituent substance) from C12-C18 in study KY080200 indicated that the data obtained were not as reliable as those that could be generated for single chain lengths due to wide solubility differences between the chain lengths. A weighted average overall solubility for the registered substance has therefore been calculated by determining the individual water solubilities of the C8-C18 chain lengths combined with the percentage active of these chain lengths. We have presented the data on KY080200 for completeness and to explain why KY090009 was carried out.
The individual chain length solubilities and the calculation approach for the weighted average are shown below.
The water solubility of the test item at two different loading rates was determined using Method A6 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC).

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Additional information

Summary of KY090009:

From Study KY090009 water solubility was determined using the flask method, Method A6 of Commission regulation (EC) No 44012008 of 30 May 2008 for the following individual chain lengths of the test item: 1) sodium octanoyl isethionate (C8); 2) sodium lauroyl isethionate (C12); 3) sodium myristoyl isethionate (C14); 4) sodium palmitoyl isethionate (C16); and 5) sodium stearoyl isethionate (C18).

The reason that single chain length water solubilities were determined in study KY090009 is that data obtained on the registered substance (multi-constituent substance) from C12-C18 in study KY080200 indicated that the data obtained were not as reliable as those that could be generated for single chain lengths due to wide solubility differences between the chain lengths. A weighted average overall solubility for the registered substance has therefore been calculated by determining the individual water solubilities of the C8-C18 chain lengths combined with the percentage active of these chain lengths. We have presented the data on KY080200 for completeness and to explain why KY090009 was carried out.

The individual chain length solubilities and the calculation approach for the weighted average are shown below.

Summary data on water solubility from KY090009:

Test Item

Overall Water Solubility

at 20.0 +/- 0.5°C (g/l)

Sodium Octanoyl Isethionate (C8)

164

Sodium Lauroyl Isethionate (C12)

48.4

Sodium Myristoyl Isethionate (C14)

0.672

Sodium Palmitoyl Isethionate (C16)

0.109

Sodium Stearoyl Isethionate (C18)

8.08 x 10-3

Calculation method used to predict overall water solubility from individual chain length data:

Test Item

Overall Solubility (g/L)

Chain length distribution (%)

Corrected Solubility (g/L)

Sodium Octanoyl Isethionate (C8)

164

4.4

7.281

Sodium Decanoyl Isethionate (C10)

62.2*

4.6

2.859

Sodium Lauroyl Isethionate (C12)

48.4

26.2

12.680

Sodium Myristoyl Isethionate (C14)

0.672

13.7

0.092

Sodium Palmitoyl Isethionate (C16)

0.109

27.8

0.030

Sodium Stearoyl Isethionate (C18)

8.08 x 10-3

22.9

1.85 x 10-3

(C20)

1.93 x 10-3*

0.36

6.95 x 10-6

*Predicted using equation y = 2E+09e-1.0364xplotted using measured solubilities from other chain lengths

Based on the table above, the overall corrected water solubility is 22.946g/L

Summary of KY080200:

The water solubility of the test item at two different loading rates was determined using Method A6 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC).

The concentrations of the individual components corrected for percentage composition are shown in the following table:

Table 12.1

Loading level (g/l)

(As Test Item)

Component

Corrected Solution Concentration (g/l) Calculated Using Distribution

10 g/l

Active C8

0.460

Active C10

0.468

Active C12

2.19

Active C14

0.468

Active C16

0.278

Active C18

0.102

75 g/l

Active C8

3.62

Active C10

3.00

Active C12

11.9

Active C14

2.12

Active C16

2.00

Active C18

0.981

The test item was a mixture of different chain lengths of varying amounts and it was not possible to saturate solutions with the individual components, consequently solubilities quoted for individual chain lengths should be taken as a guide only.