Niobium hydride

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 September 2018 to 21 November 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

1995

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

2016

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7840 (Water Solubility)

Version / remarks:

1998

Deviations:

no

GLP compliance:

yes

Type of method:

column elution method

Key result

Water solubility:

< 0.001 mg/L

Conc. based on:

element (dissolved fraction)

Remarks:

dissolved Niobium

Temp.:

20 °C

pH:

>= 7.4 - <= 7.6

Details on results:

PRELIMINARY TEST
- The content of dissolved Niobium in the water samples was ≤ 0.00061 mg/L.

MAIN STUDY
- At a flow rate of 24 mL/h, the coefficient of variation (CV) (n = 10) was > 30 %. Therefore, sampling at this flow rate was repeated. The coefficient of variation (CV) (n = 10) was ≤ 30 % at 12 mL/h and at the repeat at 24 mL/h. It demonstrated that the system was equilibrated at these flow rates.
- At these flow rates, the analysed Niobium concentrations were far below that of the lowest calibration level. The analysed Niobium concentrations are therefore reported to be below that of the lowest calibration standard multiplied by the dilution factor (i.e. < 0.000728 mg/L).
- The turbidity of the eluates was < 0.2 NTU. According to this, no undissolved particles were detected in the eluates.
- Background response of Niobium was detected in the pre-treated samples from the blank column. These responses were comparable with the responses in the test samples.

Table 1: Main Study - Water Solubility of Dissolved Niobium

Flow Rate (mL/h)	Sample No.	Niobium Concentration Analysed					pH
		Individual^1(mg/L)	Mean^2(mg/L)	CV (%)	Mean^3(mg/L)	MD (%)
24^4	1	0.00029	0.00071^6	118^4			7.4
	2	0.00028
	3	0.00080
	4	0.00025
	5	0.00026
	6	0.0026
	7	0.00025
	8	0.00025
	9	0.0018
	10	0.00028
12	1	0.00028^5	0.00022^7	12	0.00020^9	13	7.4
	2	0.0016^5
	3	0.00038^5
	4	0.00022
	5	0.00021
	6	0.00027
	7	0.00020
	8	0.00021
	9	0.00020
	10	0.00021
24	1	0.00017	0.00019^8	23			7.6
	2	0.00017
	3	0.00030
	4	0.00018
	5	0.00017
	6	0.00023
	7	0.00018
	8	0.00017
	9	0.00016
	10	0.00017

 

1: Obtained by extrapolation of the calibration curve.

2: Mean of the concentrations obtained at one flow rate.

3: Mean of the concentrations obtained at the flow rate of 12 mL/h and the repeated flow rate of 24 mL/h.

4: Coefficient of variation was >30 %, therefore sampling at this flowrate was repeated.

5: This value was not used for calculation of the mean because the system had not reached equilibrium yet.

6: The mean concentration obtained in the corresponding blank was 0.00020 mg/L.

7: A comparable mean concentration of 0.00020 mg/L was obtained in the corresponding blank.

8: A comparable mean concentration of 0.00017 mg/L was obtained in the corresponding blank.

9: The analysed concentrations were far below the lowest calibration level and are therefore reported to be below the lowest calibration standard, multiplied by the dilution factor (i.e. < 0.000728 mg/L).

Conclusions:

Under the conditions of this study the water solubility of dissolved Niobium at 20 °C was < 0.000728 mg/L.

Executive summary:

The water solubility of the test material was investigated in accordance with the standardised guidelines OECD 105, EU Method A6 and OPPTS 830.7840, under GLP conditions.

It proved not possible to dissolve the test material in nitric acid, nitric acid/hydrogen peroxide and hydrochloric acid. The test material dissolved in hydrofluoric acid but during removal of excess hydrofluoric acid using boric acid, the test material precipitated as a white solid.

For quantitative analysis, stock and calibration solutions with a known content are needed. As an alternative, an analytical standard of Niobium was purchased and used for analysis. As a result, concentrations measured are dissolved Niobium concentrations.

The column elution method was applied for the determination of the mass concentration of dissolved Niobium in water. The pH of the aqueous samples was 7.4 and 7.6.

Under the conditions of this study, the water solubility of dissolved Niobium at 20 °C was < 0.000728 mg/L.

Description of key information

Under the conditions of this study the water solubility of dissolved Niobium at 20 °C was < 0.000728 mg/L.

Key value for chemical safety assessment

Water solubility:

0.001 mg/L

at the temperature of:

20 °C

Additional information

The water solubility of the test material was investigated in accordance with the standardised guidelines OECD 105, EU Method A6 and OPPTS 830.7840, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

It proved not possible to dissolve the test material in nitric acid, nitric acid/hydrogen peroxide and hydrochloric acid. The test material dissolved in hydrofluoric acid but during removal of excess hydrofluoric acid using boric acid, the test material precipitated as a white solid.

For quantitative analysis, stock and calibration solutions with a known content are needed. As an alternative, an analytical standard of Niobium was purchased and used for analysis. As a result, concentrations measured are dissolved Niobium concentrations.

The column elution method was applied for the determination of the mass concentration of dissolved Niobium in water. The pH of the aqueous samples was 7.4 and 7.6.

Under the conditions of this study, the water solubility of dissolved Niobium at 20 °C was < 0.000728 mg/L.

 

A value of 0.001 mg/L at 20 deg C is used for risk assessment purposes.