Tricopper bis(orthophosphate)

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

26 November - 16 December 2009

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: 15 September 2009 Date of Signature on Certificate: 26 November 2009

Type of method:

flask method

Key result

Water solubility:

1.25 g/L

Temp.:

20 °C

pH:

ca. 4

See attachment for example chromatography.

Preliminary test

The preliminary estimate of water solubility was 0.959 g/L.

Definitive test

The mean peak areas relating to the standard and sample solutions are shown in the following table:

Table 4.3

Solution	Mean peak area*
Standard 30.5 mg/l	3.830
Standard 30.5 mg/l	3.772
Sample 7A	3.755
Sample 7B	3.872
Sample 6A	3.732
Sample 6B	3.872
Sample 1A	4.020
Sample 1B	4.107
Sample 2A	3.891
Sample 2B	3.988
Standard 30.5 mg/l	3.878
Standard 30.5 mg/l	3.809
Sample 3A	3.960
Sample 3B	3.969
Sample 4A	5.185
Sample 4B	4.996
Sample 5A	3.850
Sample 5B	3.854

The concentration (g/L) of test material in the sample solutions is shown in the following table:

Table 4.4

Sample Number	Time shaken at ~ 30ºC (hours)	Time equilibrated at 20ºC (hours)	Concentration (g/l)	Solution pH
1	72	24	1.31	3.6
2	72	24 [10°C]	1.27	3.7
3	72	24 [30°C]	1.26	3.6
4	72	24	1.62	4.0
5	72	24	1.23	3.9
6	48	24	1.23	3.7
7	24	24	1.21	3.7

Mean unbuffered water result (at 20.0 ± 0.5°C): 1.25 g/L.

Validation

The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0 to 100 mg/L (as orthophosphate anion). This was satisfactory with a correlation coefficient of 1.000 being obtained. This work was performed as part of Harlan Laboratories Ltd Project Number 2920/0020.

Conclusions:

Interpretation of results (migrated information): soluble (1000-10000 mg/L)
The water solubility of the test material has been determined to be 1.25 g/l of solution at 20.0 ± 0.5°C.

The effect of temperature over the range 10 to 30°C has been considered not to have had a significant influence on the solubility of the test material.

The initial solution pH was also shown to influence solubility of the test material. When using an identical initial saturation period of 72 hours, the use of the pH 4 buffer solution somewhat increased the resulting test material concentration (when compared to unbuffered water) to 1.62 g/l at 20.0 ± 0.5°C (at a final solution pH of 4.0) whereas the use of the pH 9 buffer solution had negligible effect on the test material concentration. It had been anticipated that an acidic pH would suppress solubility. However, although the pH 4 buffer solution was initially more acidic than the unbuffered water, due to its buffering capacity, increased dissolution of the test material occurred before the resulting acidic solution began to suppress test material dissolution. Therefore, although the maximum observed solubility was 1.62 g/l (at a final solution pH of 4.0), the water solubility may increase further in cases where additional buffering capacity exists.

Description of key information

Water solubility: 1.25 g/l (EU Method A.6, flask method, GLP)

Key value for chemical safety assessment

Water solubility:

1.25 g/L

at the temperature of:

20 °C