Barium bis(dihydrogenorthophosphate)

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11-Apr-2016 to 04-Aug-2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

July 27, 1995

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

May 31, 2008

GLP compliance:

yes (incl. QA statement)

Remarks:

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

Type of method:

flask method

Specific details on test material used for the study:

- Appearance: white crystalline powder
- Analytical purity: >92% based on 43 % BaO and 42 % P2O5
- Batch No.: 9000008613
- Expiration date of the lot/batch: April 23, 2017
- Storage conditions: Store dry in original tightly closed container at a well-ventilated cool place

Key result

Water solubility:

>= 27.16 - <= 28.42 g/L

Conc. based on:

test mat.

Loading of aqueous phase:

30 g/L

Temp.:

20 °C

pH:

>= 2.9 - <= 3

During the 1st main study the test material visually completely dissolved over three days of testing. In the 2nd main study undissolved white material was observed in the test item loaded vessels. The dissolved Ba concentrations indicate that all barium from the test item is dissolved. The precipitate is probably due to formation of phosphate species. Therefore, it was decided to quantify the dissolved phosphorous in respective samples.

After filtration of all samples, the solutions were clear. In order to verify this, the turbidity was measured in these samples.

The temperature in the thermostatically controlled incubation cabinet was monitored by a thermo data logger (Testo 175-T2, Testo AG, Leutkirch, Germany). The mean temperature in the 1st main test was 20.4 ± 0.2 °C. and 20.1 ± 0.1 °C in the 2nd main study.

The pH in test item loaded vessels in the 1st main test was in the range of 3.4 - 3.5, whereas the pH in method blanks ranged from 7.5 – 8.0. The pH in test item loaded vessels in the 2nd main test was in the range of 2.9 – 3.0, whereas the pH in method blanks ranged from 6.5 – 7.2.

The turbidity was measured after filtration to verify that only dissolved concentrations would get measured. The turbidity was always <1 NTU, indicating that no undissolved material was left after the filtration step.

Due to the very low LOQ (LOQ = 0.0144 µg Ba/L) of ICP-OES measurements, barium levels of method blanks are above the limit of quantification, but far below concentrations in test item loaded samples.

Phosphorous levels of method blanks are below the limit of detection (LOD = 39.1 µg P/L). Due to very low LOQ for Ba, few concentrations were above, but far below concentrations in test item loaded samples.

During the three days of testing in the first main study a complete dissolution of the test item was visually observed. Therefore the 1st main test cannot be used for determination of water solubility.

Barium concentrations in 2nd main tests were observed but this is due to a complete dissolution of Ba (see Table 1). However, the observed white precipitate in the 2nd main test is probably formed by phosphates. Therefore, the amount of dissolve P has also been quantified (see Table 2). Constant phosphorous concentrations according to the study guideline OECD 105 as well as the Regulation 440/2008/EC A.6 were measured during the study from day 1 to day 3.

The calculated amount of dissolved test item is compiled in Table 3 and Table 4 for 2nd main test in regard to Ba and P respectively.

Table 1 Measured barium concentrations in test samples in g/L in the 2nd main test (1,2 – duplicate vesssels; a,b –duplicate samples)

sample	dilution	measured	measured*	mean	SD	mean	SD	difference
name	factor	Ba	dilution	Ba conc.	Ba conc.	Ba conc.	Ba conc.	between
		[µg/L]	Ba	per vessel	per	all	all	samplings
			[g/L]	[g/L]	vessel	vessels	vessels	intervals
					[g/L]	[g/L]	[g/L]	[%]
1a d1	100000	120.763	12.076
1b d1	100000	118.621	11.862	11.969	0.151
2a d1	100000	120.842	12.084
2b d1	100000	118.393	11.839	11.962	0.173	11.965	0.005
1a d2	100000	124.248	12.425
1b d2	100000	121.512	12.151	12.288	0.193
2a d2	100000	119.451	11.945
2b d2	100000	119.412	11.941	11.943	0.003	12.116	0.244	1.3
1a d3	100000	122.857	12.286
1b d3	100000	121.281	12.128	12.207	0.111
2a d3	100000	124.683	12.468
2b d3	100000	121.937	12.194	12.331	0.194	12.269	0.088	1.3

 

Table 2 Measured phosphorous concentrations in test samples in g/L in the 2nd main test (1,2 – duplicate vesssels; a,b –duplicate samples)

sample	dilution	measured	measured*	mean	SD	mean	SD	difference
name	factor	Ba	dilution	Ba conc.	Ba conc.	Ba conc.	Ba conc.	between
		[µg/L]	Ba	per vessel	per	all	all	samplings
			[g/L]	[g/L]	vessel	vessels	vessels	intervals
					[g/L]	[g/L]	[g/L]	[%]
1a d1	20000	258.9	5.178
1b d1	20000	242.9	4.858	5.018	0.226
2a d1	20000	255.3	5.106
2b d1	20000	254.1	5.082	5.094	0.017	5.056	0.054
1a d2	20000	272	5.440
1b d2	20000	267.9	5.358	5.399	0.058
2a d2	20000	253.1	5.062
2b d2	20000	261.6	5.232	5.147	0.120	5.273	0.178	4.3
1a d3	40000	132.5	5.300
1b d3	40000	121.7	4.868	5.084	0.305
2a d3	40000	136.1	5.444
2b d3	40000	134	5.360	5.402	0.059	5.243	0.225	-0.6

 

Table 3 Calculated amount of solved test item d1– d3 in regard to Ba

	mean dissolved Ba d1-d3 [g/L]	SD dissolved Ba d1-d3 [g/L]	percentage of Ba in test item [%] #	mean calculated dissolved test item d1-d3 [g/L]	SD calculated dissolved test item d1-d3 [g/L]	loading [g/L]	percentage test item dissolved in regard to Ba [%]
vessel 1	12.15	0.17	40.13	30.19	0.41	30.00	100.6
vessel 2	12.08	0.22		30.10	0.55	30.01	100.3
all vessels	12.12	0.15		30.19	0.378

Table 4 Calculated amount of solved test item d1– d3 in regard to P

	mean dissolved P d1-d3 [g/L]	SD dissolved P d1-d3 [g/L]	percentage of P in test item [%] #	mean calculated dissolved test item d1-d3 [g/L]	SD calculated dissolved test item d1-d3 [g/L]	loading [g/L]	percentage test item dissolved in regard to P [%]
vessel 1	5.17	0.20	18.68	27.66	1.09	30.00	92.2
vessel 2	5.21	0.16	18.68	27.92	0.88	30.01	93.0
all vessels	5.19	0.12	18.68	27.79	0.63

The amount of barium bis(dihydrogenphosphate) dissolved was calculated by:
 = mean of measured values * 100 % / 18.68 %

mean calculated barium bis(dihydrogenphosphate) dissolved day 1 – day 3:
              Vessel 1: 27.66 ± 1.09 g/L
              Vessel 2: 27.92 ± 0.88 g/L

Description of key information

water solubility: 27.79 ± 0.63 g/L at loading rate 30 g/L, 20 °C and pH 2.9 - 3.0 (OECD 105, EU A.6., flask method)

Key value for chemical safety assessment

Water solubility:

27.79 g/L

at the temperature of:

20 °C

Additional information

The water solubility of the test item was determined using flask method according to OECD 105 and EU Method A.6. A solubility equilibrium was observed during the test with a loading of 30 g/L test item in regard to phosphorous.