Bismuth citrate

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20 January 2010 to 9 February 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted in accordance with EU and OECD guidelines and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

See below

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

yes

Remarks:

See below

Principles of method if other than guideline:

Deviation from the Guideline: Deionised water was used for the determination of the solubility in water of Bismuth hydroxide nitrate oxide, instead of doubly distilled water, as the validation showed, that the usage of deionised water was acceptable for the determination of the solubility in water of Bismuth compounds. This is considered as uncritical concerning the outcome of the study.

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Water solubility:

10.97 - 53.81 mg/L

Temp.:

20 °C

Remarks on result:

other: Standard deviation of all samples was 14.6 mg/L

Details on results:

The replicates showed poor correspondence. The standard deviation (all samples) was 14.6 mg/L, corresponding to a relative standard deviation of 48 %. The concentration of Bismuth citrate in water lies in a range of 10.97 and 53.81 mg/L. The repetition of the measurement on day 6 showed comparable findings. Dependency of solubility on pH was not observed.
Accuracy measurements via standard addition showed a correlation of 0.991, indicating that matrix effects were insignificant.
No observations arousing doubts concerning the accuracy of the results and the validity of the study were made.

Measurements during Equilibration

The data which was acquired during equilibration is presented in the following table:

Day	Flask	Temperature in °C	pH	Dilution factor	Bi Concentration in mg/L	Difference to previous sample	Concentration test item in mg/L
1	1	20.0	6	10	1.990	-	37.91
2	1	20.3	6	10	2.390	+ 20.1 %	45.52
5	1	20.5	6	10	2.825	+ 18.2 %	53.81
6	1	20.5	5.81	10	2.804	- 0.74 %	53.41

After the analysis of the sample of day 3, the plateau was considered as reached.

Measurements at Plateau

The following table gives the values which were measured at the plateau:

Flask	2	3	4	5	6
pH	5.00	4.80	4.70	5.19	5.49
First Measurement
Concentration Bi in mg/L (diluted sample)	0.576	0.685	1.211	1.556	1.819
Dilution factor (original sample)	10	10	10	10	10
Concentration Bi in mg/L	5.76	6.85	12.11	15.56	18.19
Factor	0.525	0.525	0.525	0.525	0.525
Concentration test item in mg/L	10.97	13.05	23.06	29.63	34.66
Second Measurement
Concentration Bi in mg/L (diluted sample) repetition	0.657	0.726	1.366	1.665	1.963
Dilution factor	10	10	10	10	10
Concentration Bi in mg/L (original sample) repetition	6.57	7.26	13.66	16.65	19.63
Concentration test item in mg/L repetition	12.51	13.82	26.02	31.72	37.40

Because of high deviation of flasks 2 - 6 from flask 1, measurements of flasks 2 - 6 on day 6 was repeated and showed comparable values. Because the concentration plateau was reached not until day 5 the measurements of the days 1 and 2 are not included in the calculation of the mean:

Day	Mean Cone. Bismuth citrate (mg/L)	Total Mean (mg/L)	Total Stand. Dev.
5	53.81	28.34	14.90 (52.6%)
6	53.41
6	10.97
6	13.05
6	23.06
6	29.63
6	34.66
6	12.51
6	13.82
6	26.02
6	31.72
6	37.40

 

Conclusions:

Interpretation of results (migrated information): slightly soluble (0.1-100 mg/L)
Using the flask method, at the plateau, the concentration of Bismuth citrate in water lies in the range of 10.97 and 53.81 mg/L. The standard deviation (all samples) was 14.6 mg/L, corresponding to a relative standard deviation of 48 %.  

Executive summary:

After two pre-tests, the water solubility was estimated to be > 10 mg/L. Therefore, the flask method was employed.

For the flask method, 400 - 1080 mg/L were weighed into each of six individual vessels, water was added, and the vessels were shaken at 20 ± 0.5 °C.

On the days 1, 2, 5 and 6, vessel 1 was taken from the shaking apparatus and stored at 20 ± 0.5 °C for equilibration. Samples were taken, centrifuged or filtrated and analysed using AAS as shaking of the test vessels was continued.

No differences above 15% in the concentration of the solution could be determined between the sampling dates 5 and 6, supporting the hypothesis, that the maximum concentration of the test item had been reached. Therefore, on day 6, vessels 2-6 were sampled and analysed in the same fashion.

At the plateau, the concentration of Bismuth citrate in water lay in the range of 10.97 - 53.81 mg/L at 20 ± 0.5 °C.

Description of key information

The water solubility of bismuth citrate ranges from 10.97 to 53.81 mg/L.

Key value for chemical safety assessment

Water solubility:

10.97 mg/L

at the temperature of:

20 °C

Additional information

A study was conducted to determine the water solubility of bismuth citrate in accordance with OECD Guideline 105 and EU Method A.6.

Using the flask method, at the plateau, the concentration of bismuth citrate in water lies in the range of 10.97 and 53.81 mg/L. The standard deviation (all samples) was 14.6 mg/L, corresponding to a relative standard deviation of 48 %.