Pyrasulfotole

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

8 May 2003 - 30 Dec 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

GLP certifying authority: Hess. Ministerium für Umwelt, Landwirtschaft und Forsten, Wiesbaden, Germany

Type of method:

flask method

Key result

Water solubility:

4.2 g/L

Conc. based on:

test mat.

Incubation duration:

72 h

Temp.:

20 °C

pH:

4

Remarks on result:

other: Blank Buffer pH is 4.0; measured pH is 3.9

Key result

Water solubility:

69.1 g/L

Conc. based on:

test mat.

Incubation duration:

72 h

Temp.:

20 °C

pH:

7.07

Remarks on result:

other: Blank Buffer pH is 7.07; measured pH is 5.4

Key result

Water solubility:

49 g/L

Conc. based on:

test mat.

Incubation duration:

72 h

Temp.:

20 °C

pH:

9.02

Remarks on result:

other: Blank Buffer pH is 9.02; measured pH is 5.2

Key result

Water solubility:

2.3 g/L

Conc. based on:

test mat.

Incubation duration:

72 h

Temp.:

20 °C

pH:

6.11

Remarks on result:

other: pH of Blank Bidistilled Water is 6.11; measured pH is 3.0

Individual Results -Water solubility of test item for different time intervals

Note: Measured pH values (for pH buffers 7 and 9) differ from blank pH values because of limited buffer capacity.

Result for pH 4 Buffer:

Experiment	1	2	3	Blank
Amount of test item(mg)	107.9	102.2	107.0	-
Stirring time at 30°C(h)	24	48	72	72
pH at room temperature	3.89	3.91	3.87	4.00
Water solubility(g/L)	4.26	4.17	4.22	-

Results for pH 7 Buffer:

Experiment	1	2	3	Blank
Amount of test item(mg)	620.5	674.6	667.1
Stirring time at 30°C(h)	24	48	72	72
pH at room temperature	5.44	5.43	5.41	7.07
Water solubility (g/L)	69.0	69.4	69.0	-

Results for pH 9 Buffer:

Experiment	1	2	3	Blank
Amount of test item(mg)	604.4	590.7	623.8	-
Stirring time at 30°C(h)	24	48	72	72
pH at room temperature	5.17	5.16	5.18	9.02
Water solubility(g/L)	49.8	49.1	48.0	-

Results for Bidistilled Water:

Experiment	1	2	3	Blank
Amount of test item(mg)	103.1	104.6	108.2	-
Stirring time at 30°C(h)	24	48	72	72
pH at room temperature	2.97	3.05	2.99	6.11
Water solubility (g/L)	2.4	2.2	2.2	-

Final Result – Water Solubility

The water solubility of the test item at pH 4, pH 7, pH 9 and bidistilled water at 20 °C has been determined according to the "flask method" described in guideline 92/69/EEC, appendix A.6 and OECD-guideline 105.  The results of the solubility measurements are given in the following table.

Solubility	pH measured^1	Water Solubility (20°C) of test item     (g/L)	Std Dev (g/L)	RSD   %
pH4(0.05mol/L)	3.9	4.2	0.05	1.1
pH7(0.3mol/L)	5.4	69.1	0.24	0.4
pH9(0.3mol/L)	5.2	49.0	0.91	1.9
bidistilled water	3.0	2.3	0.09	4.2

¹Mean experiment 1 to 3, after dissolution of test material.

A further increase of the concentration of the buffers at pH 7 and pH 9 is not possible because of the limited solubility of the buffer components. The dissolved buffer components could also influence the solubility of the test item.

Description of key information

Water solubility of test item at 20 ºC:

pH 4 buffer       4.2 g/L

pH 7 buffer       69.1 g/L

pH 9 buffer       49.0 g/L

pH 3 bidistilled water 2.3 g/L         

(OECD 105, flask method)             

  

Key value for chemical safety assessment

Water solubility:

69.1 g/L

at the temperature of:

20 °C

Additional information

at pH 7