Dicopper hydroxide phosphate

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2014.04.16 - 2014.09.22

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

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:

No screening to maximize the dissolution pH was done. pH 5.5 had been chosen based on previous data.

GLP compliance:

yes (incl. QA statement)

Remarks:

Ministerium für Arbeit, Integration und Soziales des Landes Nordrhein-Westfalen

Type of method:

other: ICP-OES

Specific details on test material used for the study:

- Name of test material (as cited in study report): Dicopper hydroxide phosphate
- Physical state: powder

Key result

Water solubility:

168.1 µg/L

Temp.:

21.5 °C

pH:

5.5

Remarks on result:

other: Dissolved copper concentrations at loading of 1 mg/L of test item after 24 h (1d)

Water solubility:

202.3 µg/L

Temp.:

21.5 °C

pH:

5.5

Remarks on result:

other: Dissolved copper concentrations at loading of 1 mg/L of test item after 168 h (7 d)

Water solubility:

216.2 µg/L

Temp.:

21.5 °C

pH:

5.5

Remarks on result:

other: Dissolved copper concentrations at loading of 1 mg/L of test item after 672 h (28 d)

Water solubility:

36.14 µg/L

Temp.:

21.5 °C

pH:

5.5

Remarks on result:

other: Dissolved copper concentrations at loading of 0.1 mg/L of test item after 24 h (1d)

Water solubility:

41.5 µg/L

Temp.:

21.5 °C

pH:

5.5

Remarks on result:

other: Dissolved copper concentrations at loading of 0.1 mg/L of test item after 168 h (7 d)

Dissolved Cu concentrations in test with the loading of 1 mg/L and media at pH 5.5 (1, 2, 3 - triplicate vessels; a, b - duplicate samples per vessel)

sample name and day	dilution factor	Cu conc. measured* dilution [µg/L]	mean Cu conc. per vessel [µg/L]	SD Cu conc. per vessel [µg/L]	within vessel variation [%]	mean Cu conc. all samples [µg/L]	SD Cu conc. all samples [µg/L]	Between vessel variation [%]	difference between samplings [%]
1a d1	2	172.2	172.8	0.9	0.5	168.1	4.3	2.6
1b d1	2	173.4
2a d1	2	163.0	163.2	0.1	0.1
2b d1	2	163.3
3a d1	2	168.0	168.3	0.4	0.2
3b d1	2	168.6
1a d7	2	202.5	203.2	1.1	0.5	202.3	2.1	1.0	20.4
1b d7	2	204.0
2a d7	2	199.4	200.2	1.1	0.6
2b d7	2	201.0
3a d7	2	202.2	203.6	2.1	1.0
3b d7	2	205.1
1a d28	2	217.9	219.1	1.8	0.8	216.2	3.6	1.7	6.9
1b d28	2	220.4
2a d28	2	214.8	217.2	3.4	1.6
2b d28	2	219.6
3a d28	2	211.4	212.4	1.4	0.6
3b d28	2	213.3

Dissolved Cu concentrations in test with the loading of 0.1 mg/L and media at pH 5.5 (1, 2, 3 - triplicate vessels; a, b - duplicate samples per vessel)

sample name and day	dilution factor	Cu conc. measured* dilution [µg/L]	mean Cu conc. per vessel [µg/L]	SD Cu conc. per vessel [µg/L]	within vessel variation [%]	mean Cu conc. all samples [µg/L]	SD Cu conc. all samples [µg/L]	Between vessel variation [%]	difference between samplings [%]
1a d1	1	33.30	33.76	0.65	1.9	36.14	3.40	9.4
1b d1	1	34.23
2a d1	1	39.94	40.03	0.13	0.3
2b d1	1	40.11
3a d1	1	37.01	34.63	3.37	9.7
3b d1	1	32.25
1a d7	1	40.50	40.46	0.06	0.2	41.50	1.84	4.4	14.8
1b d7	1	40.41
2a d7	1	43.72	43.86	0.20	0.5
2b d7	1	44.01
3a d7	1	40.34	40.18	0.23	0.6
3b d7	1	40.02

Solution pH and oxygen concentrations

In solutions containing 1 and 0.1 mg/L of the test item and in respective method blanks at pH 5.5, pH ranged from 5.5 - 6.2 and 5.4 - 5.9, respectively.

Oxygen levels of all test solutions (all loadings) were in the range recommended by the OECD Test Guidance 29 during the test: above 70 % of oxygen saturation at 8.5 mg/L (70 % of 8.5 mg/L = 6 mg/L)

Mass balance

For each loading two vessels were exemplarily chosen.

Copper recoveries for the test with 1 mg/L ranged from of 99.2 to 99.5 %.

Rinsing of filters from the test with 1 mg/L loading was not necessary because the recoveries were within the QA/QC requirements of 100 ± 15 %; recoveries ranged from 99.2 to 99.5 %.

For the test with 0.1 mg/L the QA/QC requirements for the recoveries were set to 100 ± 25 % due to increasing inaccuracy with decreasing loading (pipettes, balance, volumetric flasks, etc.).

Rinsing of filters from the test with 0.1 mg/L loading was not necessary because copper was within the QA/QC requirements of 100 ± 25 %; recoveries ranged from 80.9 to 86.9 %.

Conclusions:

Dissolved copper concentrations of the test substance at pH 5.5 at 21.5 °C (OECD 29):
- At loading rate of 1 mg/L test item: 168.1 µg/L after 24 h (1 d)
- At loading rate of 1 mg/L test item: 202.3 µg/L after 168 h (7 d)
- At loading rate of 1 mg/L test item: 216.2 µg/L after 672 h (28 d)

- At loading rate of 0.1 mg/L test item: 36.14 µg/L after 24 h (1 d)
- At loading rate of 0.1 mg/L test item: 41.5 µg/L after 168 h (7 d)

Reference 2

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Testing was conducted between 02 October 2009 and 19 November 2009.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

30 May 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: 2009-09-15 Date of Signature: 2009-11-26

Type of method:

flask method

Specific details on test material used for the study:

Sponsor's identification: Dicopper hydroxide phosphate
Description: light green powder
CAS number: 12158-74-6
Lot number: 90101
Date received: 28 August 2009
Storage conditions: room temperature in the dark

Key result

Water solubility:

0.043 g/L

Temp.:

20 °C

pH:

5.4 - 5.7

Details on results:

Please see section Remarks on results including tables and figures.

Results

Preliminary test

The preliminary estimate of water solubility was 4.46 x 10^-2 g/l.

Definitive test

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

Solution	Mean peak area*
Standard 30.6 mg/l	3.956
Standard 30.6 mg/l	3.959
Sample 1A	1.674
Sample 1B	1.635
Standard 30.6 mg/l	3.969
Standard 30.6 mg/l	3.962
Sample 2A	0.939
Sample 2B	0.940
Standard 30.6 mg/l	3.961
Standard 30.6 mg/l	3.947
Sample 3A	1.211
Sample 3B	1.234
Sample 4A	1.210
Sample 4B	1.209
Sample 5A	1.276
Sample 5B	1.213
Sample 6A	1.210
Sample 6B	1.225
Sample 7A	1.179
Sample 7B	1.173

 

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

Sample Number	Time shaken at ~ 30ºC (hours)	Time equilibrated at 20ºC (hours)	Concentration (g/l)	Solution pH
1	72	24	0.644	3.9
2	72	24	3.65 x 10^-2	8.5
3	72	24 [30ºC]	4.77 x 10^-2	5.4
4	72	24 [10ºC]	4.71 x 10^-2	5.4 to 5.5
5	72	24	4.85 x 10^-2	5.3 to 5.4
6	48	24	4.74 x 10^-2	5.5 to 5.6
7	24	24	4.58 x 10^-2	5.6 to 5.7

*corrected for the relevant blan

Validation

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

*as the orthophosphate anion

Conclusions:

The water solubility of the test material has been determined to be 4.73 x 10-2 g/L of solution at 20.0 ± 0.5°C.

Executive summary:

The water solubility has been determined to be 4.73 x 10^-2g/L of solution at 20.0±0.5°C,using the flask method, Method A6 Water Solubility of Commission Regulation (EC) No 440/2008 of 30 May 2008.

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 (range 4.71 x 10^-2to 4.77 x 10^-2g/L).

The initial solution pH was also shown to significantly 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 phosphate concentration dissolved (when compared to unbuffered water) whereas the use of the pH 9 buffer solution slightly decreased the analysed phosphate 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 0.644 g/L (at a final solution pH of 3.9), the water solubility may increase further in cases where additional buffering capacity exists.

Reference 3

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2014.04.16 - 2014.09.23

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Remarks:

The information on the test material was recorded insufficiently, therefore the study is considered not assignable for assessment of T/D properties of the test material registered.

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:

No screening to maximize the dissolution pH was done. pH 5.5 had been chosen based on previous data.

GLP compliance:

yes (incl. QA statement)

Remarks:

Ministerium für Arbeit, Integration und Soziales des Landes Nordrhein-Westfalen

Type of method:

other: ICP-OES

Specific details on test material used for the study:

- Name of test material (as cited in study report): Dicopper hydroxide phosphate
- Physical state: powder
- Analytical purity: ca. 98%

Water solubility:

69.53 µg/L

Temp.:

21.5 °C

pH:

5.5

Remarks on result:

other: Dissolved copper concentrations at loading of 1 mg/L of test item after 24 h (1d)

Water solubility:

138.2 µg/L

Temp.:

21.5 °C

pH:

5.5

Remarks on result:

other: Dissolved copper concentrations at loading of 1 mg/L of test item after 168 h (7 d)

Water solubility:

158.8 µg/L

Temp.:

21.5 °C

pH:

5.5

Remarks on result:

other: Dissolved copper concentrations at loading of 1 mg/L of test item after 672 h (28 d)

Water solubility:

28.81 µg/L

Temp.:

21.5 °C

pH:

5.5

Remarks on result:

other: Dissolved copper concentrations at loading of 0.1 mg/L of test item after 24 h (1d)

Water solubility:

44.62 µg/L

Temp.:

21.5 °C

pH:

5.5

Remarks on result:

other: Dissolved copper concentrations at loading of 0.1 mg/L of test item after 168 h (7 d)

Dissolved Cu concentrations in test with the loading of 1 mg/L and media at pH 5.5 (1, 2, 3 - triplicate vessels; a, b - duplicate samples per vessel)

sample name and day	dilution factor	Cu conc. measured* dilution [µg/L]	mean Cu conc. per vessel [µg/L]	SD Cu conc. per vessel [µg/L]	within vessel variation [%]	mean Cu conc. all samples [µg/L]	SD Cu conc. all samples [µg/L]	Between vessel variation [%]	difference between samplings [%]
1a d1	2	75.7	76.00	0.49	0.6	69.53	5.02	7.2
1b d1	2	76.3
2a d1	2	66.0	66.01	0.05	0.1
2b d1	2	66.0
3a d1	2	66.7	66.60	0.13	0.2
3b d1	2	66.5
1a d7	2	146.4	146.6	0.1	0.1	138.2	6.5	4.7	98.8
1b d7	2	146.7
2a d7	2	132.7	133.9	1.7	1.3
2b d7	2	135.1
3a d7	2	133.6	134.1	0.8	0.6
3b d7	2	134.7
1a d28	2	160.1	160.5	0.5	0.3	158.8	4.0	2.5	14.9
1b d28	2	160.9
2a d28	2	161.7	162.1	0.6	0.3
2b d28	2	162.5
3a d28	2	152.3	154.0	2.4	1.6
3b d28	2	155.7

Dissolved Cu concentrations in test with the loading of 0.1 mg/L and media at pH 5.5 (1, 2, 3 - triplicate vessels; a, b - duplicate samples per vessel)

sample name and day	dilution factor	Cu conc. measured* dilution [µg/L]	mean Cu conc. per vessel [µg/L]	SD Cu conc. per vessel [µg/L]	within vessel variation [%]	mean Cu conc. all samples [µg/L]	SD Cu conc. all samples [µg/L]	Between vessel variation [%]	difference between samplings [%]
1a d1	1	34.15	34.08	0.10	0.3	28.81	4.62	16.0
1b d1	1	34.01
2a d1	1	23.70	23.77	0.10	0.4
2b d1	1	23.84
3a d1	1	28.44	28.58	0.19	0.7
3b d1	1	28.72
1a d7	1	53.89	54.33	0.62	1.1	44.62	7.83	17.5	54.9
1b d7	1	54.77
2a d7	1	37.44	37.37	0.11	0.3
2b d7	1	37.29
3a d7	1	41.93	42.16	0.32	0.8
3b d7	1	42.38

Solution pH and oxygen concentrations

In solutions containing 1 and 0.1 mg/L of the test item and in method blanks at pH 5.5, pH ranged from 5.4 - 6.1 and 5.5 - 6.0, respectively.

Oxygen levels of all test solutions (all loadings) were in the range recommended by the OECD Test Guidance 29 during the test: above 70 % of oxygen saturation at 8.5 mg/L (70 % of 8.5 mg/L = 6 mg/L)

Mass balance

For each loading two vessels were exemplarily chosen.

Copper recoveries for the test with 1 µg/L ranged from of 100 to 102 %.

Rinsing of filters from the test with 1 µg/L loading was not necessary because the recoveries were within the QA/QC requirements of 100 ± 15 %; recoveries ranged from 99.0 to 102 %.

For the test with 0.1 µg/L the QA/QC requirements for the recoveries were set to 100 ± 25 % due to increasing inaccuracy with decreasing loading (pipettes, balance, volumetric flasks, etc.).

Rinsing of filters from the test with 0.1 µg/L loading was not necessary because copper was within the QA/QC requirements of 100 ± 25 %; recoveries ranged from 95.5 to 102 %

Conclusions:

Dissolved copper concentrations of the test item at pH 5.5 at 21.5 °C (OECD 29):
- At loading rate of 1 mg/L test item: 69.53 µg/L after 24 h (1 d)
- At loading rate of 1 mg/L test item: 138.2 µg/L after 168 h (7 d)
- At loading rate of 1 mg/L test item: 158.8 µg/L after 672 h (28 d)

- At loading rate of 0.1 mg/L test item: 28.81 µg/L after 24 h (1 d)
- At loading rate of 0.1 mg/L test item: 44.62 µg/L after 168 h (7 d)

Description of key information

The water solubility of the test material has been determined to be 4.73 x 10-2 g/L of solution at 20.0 ± 0.5°C.

The transformation/dissolution at a loading of 1 mg/L of the test substance determined dissolved copper concentrations of 168.1 ± 4.3μg/L after 24 h (1 d), 202.3 ± 2.1μg/L after 168 h (7 d) and 216.2 ± 3.6μg/L after 672 h (28 d) at pH 5.5.

Key value for chemical safety assessment

Water solubility:

47.3 mg/L

at the temperature of:

20 °C

Additional information

One key study for water solubility and one for transformation/dissolution exists.

The water solubility study was performed in accordance with an accepted method (EU Method A.6) and under the conditions of GLP. The determination was carried out by visual assessment using a flask method, based on Method A6 Water Solubility of Commission Regulation (EC) No 440/2008 of 30 May 2008. The water solubility of the test material has been determined to be 4.73 x 10-2 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 (range 4.71 x 10-2to 4.77 x 10-2 g/L). The initial solution pH was also shown to significantly 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 phosphate concentration dissolved (when compared to unbuffered water) whereas the use of the pH 9 buffer solution slightly decreased the analysed phosphate 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 0.644 g/L (at a final solution pH of 3.9), the water solubility may increase further in cases where additional buffering capacity exists.

 

A key study was performed to determine the transformation/dissolution of dicopper hydroxide phosphate according to OECD guidance document 29 (2001). The full test at a pH of 5.5 with a loading of 1 mg/L over 28 days (long-term endpoint) and samplings after 24 h, 168 h and 672 h was done. The test was performed in triplicate vessels (agitation at 100 rpm, 21.5 ± 1.5 °C) and duplicate samples per vessel, this includes method blanks. After evaluation of the results it was decided to test dicopper hydroxide phosphate in medium at pH 5.5 (i.e. the pH that maximises dissolution) with a loading of 0.1 mg/L for 7 d and samplings after 24 h and 168 h. Solution pH, oxygen concentrations and total dissolved copper concentrations were measured at each sampling time for each loading. Oxygen levels as well as mean temperatures of both loadings are in compliance with the requirements of the OECD guidance document 29. In solutions containing 1.0 and 0.1 mg/L of the test item and in method blanks at pH 5.5, the pH ranged from 5.4 – 6.2 and 5.5 – 5.9, respectively. Under the described conditions of this test with dicopper hydroxide at a loading of 1 mg/L, dissolved copper concentrations were 168.1 ± 4.3 μg/L after 24 h (1 d), 202.3 ± 2.1 μg/L after 168 h (7 d) and 216.2 ± 3.6 μg/L after 672 h (28 d) at pH 5.5. Under the described conditions of this test with dicopper hydroxide at a loading of 0.1 mg/L, dissolved copper concentrations were 36.14 ± 3.40 μg/L after 24 h (1 d), and 41.50 ± 1.84 μg/L after 168 h (7 d).