Tungsten hexachloride

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-07-17 to 2017-10-02

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Combination of guideline studies

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

dated July 27, 1995

Deviations:

yes

Remarks:

due to the properties of the test item (e.g. rapid hydrolysis in contact with water), this standard test guideline was not generally applicable and substantial modifications were necessary.

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

Council Regulation (EC) No 440/2008

Deviations:

yes

Remarks:

due to the properties of the test item (e.g. rapid hydrolysis in contact with water), this standard test guideline was not generally applicable and substantial modifications were necessary.

Qualifier:

according to guideline

Guideline:

OECD Series on Testing and Assessment No. 29 (23-Jul-2001): Guidance document on transformation/dissolution of metals and metal compounds in aqueous media

Deviations:

yes

Remarks:

due to the properties of the test item (e.g. rapid hydrolysis in contact with water), this standard test guideline was not generally applicable and substantial modifications were necessary.

Qualifier:

according to guideline

Guideline:

other: OECD Guideline for the testing of chemicals, 111 "Hydrolysis as a Function of pH"

Version / remarks:

dated April 13, 2004

Deviations:

yes

Remarks:

due to the properties of the test item (e.g. rapid hydrolysis in contact with water), this standard test guideline was not generally applicable and substantial modifications were necessary.

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Water solubility:

>= 20 - <= 42.1 µg/L

Conc. based on:

element (dissolved fraction)

Remarks:

tungsten

Incubation duration:

30 min

Temp.:

25 °C

pH:

>= 2 - <= 3

Remarks on result:

other: Loading of aqueous phase: refer to "any other information on results incl. tables"; Temperature range: 20-25 °C.

Water solubility:

>= 38.6 - <= 39.1 µg/L

Conc. based on:

element (dissolved fraction)

Remarks:

tungsten

Incubation duration:

30 min

Temp.:

25 °C

pH:

4

Remarks on result:

other: Loading of aqueous phase: refer to "any other information on results incl. tables"; Temperature range: 20-25 °C.

Water solubility:

>= 44.7 - <= 44.9 µg/L

Conc. based on:

element (dissolved fraction)

Remarks:

tungsten

Incubation duration:

30 min

Temp.:

25 °C

pH:

7

Remarks on result:

other: Loading of aqueous phase: refer to "any other information on results incl. tables"; Temperature range: 20-25 °C.

Water solubility:

>= 44.6 - <= 46.1 µg/L

Conc. based on:

element (dissolved fraction)

Remarks:

tungsten

Incubation duration:

30 min

Temp.:

25 °C

pH:

9

Remarks on result:

other: Loading of aqueous phase: refer to "any other information on results incl. tables"; Temperature range: 20-25 °C.

Test Item in Water

The following table represents the results obtained from each analysis of the fivefold preparation of the test item in water:

preparation	sample mass [mg]	nominal concentration of tungsten in sample solution [µg/L]	actual concentration of tungsten in sample solution [µg/L]	recovery of tungsten in sample solution [%]
1	654	607	40.6	6.7
2	558	517	20.0	3.9
3	660	611	42.1	6.9
4	608	564	30.4	5.4
5	603	559	24.1	4.3
			mean	5.4
			SD	1.4
			RSD [%]	25.0

Test Item in Water after pH Adjustment

The following table represents the results obtained from each analysis of the threefold preparation of the test item in water adjusted to pH 4, pH 7, and pH 9:

preparation	pH value	sample mass [mg]	nominal concentration of tungsten in sample solution [µg/L]	actual concentration of tungsten in sample solution [µg/L]	recovery of tungsten in sample solution [%]
1	4	654	607	38.6	6.4
2	4	654	607	39.1	6.4
3	4	654	607	39.1	6.4
				mean	6.4
				SD	0.05
				RSD [%]	0.8
1	7	654	607	44.9	7.4
2	7	654	607	44.7	7.4
3	7	654	607	44.8	7.4
				mean	7.4
				SD	0.02
				RSD [%]	0.3
1	9	654	607	46.1	7.6
2	9	654	607	44.6	7.3
3	9	654	607	45.4	7.5
				mean	7.5
				SD	0.12
				RSD [%]	1.6

Conclusions:

The determined concentrations of tungsten in the sample solution after preparation of the test item in water varied between 20.0–42.1 µg/L, corresponding to a mean recovery of 5.4 % ± 1.4 %.
The determined concentrations of tungsten in the sample solution after preparation of the test item in water and pH adjustment to pH 4, pH 7 resp. pH 9 were between 38.6–39.1 µg/L, 44.7–44.9 µg/L resp. 44.6–46.1 µg/L, corresponding to mean recoveries of 6.4 % ± 0.05 %, 7.4 % ± 0.02 % resp. 7.5 % ± 0.12 %.

Executive summary:

The determined concentrations of tungsten in the sample solution after preparation of the test item in water varied between 20.0–42.1 µg/L, corresponding to a mean recovery of 5.4 % ± 1.4 %.

The determined concentrations of tungsten in the sample solution after preparation of the test item in water and pH adjustment to pH 4, pH 7 resp. pH 9 were between 38.6–39.1 µg/L, 44.7–44.9 µg/L resp. 44.6–46.1 µg/L, corresponding to mean recoveries of 6.4 % ± 0.05 %, 7.4 % ± 0.02 % resp. 7.5 % ± 0.12 %.

It can be summarised, that referring to the results of the pre-tests, tungsten hexachloride showed a rapid hydrolysis in contact with aqueous solutions. A temperature rise during the addition of aqueous solutions was observed due to the exothermic reaction. The dispersion of the WCl6 test item with water was acidic (pH-value 2–3) and within the study, after approx. 30 minutes agitation whilst cooling, an insoluble residue occured in water.

Description of key information

The determined concentrations of tungsten in the sample solution after preparation of the test item in water varied between 20.0 - 42.1 µg/L, corresponding to a mean recovery of 5.4 % ± 1.4 %.

The determined concentrations of tungsten in the sample solution after preparation of the test item in water and pH adjustment to pH 4, pH 7 resp. pH 9 were between 38.6 - 39.1 µg/L, 44.7 - 44.9 µg/L resp. 44.6 - 46.1 µg/L, corresponding to mean recoveries of 6.4 % ± 0.05 %, 7.4 % ± 0.02 % resp. 7.5 % ± 0.12 %.

It can be summarised, that referring to the results of the pre-tests, tungsten hexachloride showed a rapid hydrolysis in contact with aqueous solutions. A temperature rise during the addition of aqueous solutions was observed due to the exothermic reaction. The dispersion of the WCl6 test item with water was acidic (pH-value 2 - 3) and within the study, after approx. 30 minutes agitation whilst cooling, an insoluble residue occured in water.

Key value for chemical safety assessment

Water solubility:

46.1 µg/L

at the temperature of:

25 °C