Dichromium nitride

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the physicochemical properties of the substance indicate that it can be expected to have a low potential for adsorption

Cross-reference

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-11-4 to 2017-12-13

Reliability:

1 (reliable without restriction)

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:

no

GLP compliance:

no

Other quality assurance:

ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)

Remarks:

Accreditation certificate no. L075 valid from 12-11-1993 to 01-12-2021 (WLN Business B.V., ICP-MS) Accreditation certificate no. L043 valid from 01-06-2017 to 01-06-2021 (Vitens N.V. Laboratorium, Ionchromograph)

Type of method:

flask method

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH = 6, separation of solid phase by filtration 0.2 µm

Remarks on result:

other:

Remarks:

Cr(total) and Cr(6+) concentrations of all replicates below respective reporting limits (0.5 µg/L Cr, 0.05 µg/L Cr6+)

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH = 8, separation of solid phase by filtration 0.2 µm

Remarks on result:

other:

Remarks:

Cr(total) and Cr(6+) concentrations of all replicates below respective reporting limits (0.5 µg/L Cr, 0.05 µg/L Cr6+)

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH = 6, separation of solid phase by filtration 0.2 µm

Remarks on result:

other:

Remarks:

Cr(total) and Cr(6+) concentrations of all replicates below respective reporting limits (0.5 µg/L Cr, 0.05 µg/L Cr6+)

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH = 8, separation of solid phase by filtration 0.2 µm

Remarks on result:

other:

Remarks:

Cr(total) and Cr(6+) concentrations of all replicates below respective reporting limits (0.5 µg/L Cr, 0.05 µg/L Cr6+)

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH = 6, separation of solid phase by filtration 0.2 µm

Remarks on result:

other:

Remarks:

Cr(total) and Cr(6+) concentrations of all replicates below respective reporting limits (0.5 µg/L Cr, 0.05 µg/L Cr6+)

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Cr

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH = 8, separation of solid phase by filtration 0.2 µm

Remarks on result:

other:

Remarks:

Cr(total) and Cr(6+) concentrations of all replicates below respective reporting limits (0.5 µg/L Cr, 0.05 µg/L Cr6+)

Total Chromium concentrations in blank control vessels:

Chromium concentrations of all blank control vessels were below reporting limits irrespective of pH and sampling point (24h, 7d, 28d)

Solution pH, oxygen concentrations and temperature

Solution pH: The test item has no immediate influence on the pH of the test system. The pH measured in the medium at the start of the test, and in the blank and test item vessels during the test at pH 6 and pH 8 varied from 5.97 to 6.03 and from 7.99 to 8.03, respectively. The measured data at pH 6 and pH 8 were within the specifications of ± 0.2 units of pH.

Dissolved oxygen concentrations:

The dissolved oxygen concentration measured in the blank and test item vessels at pH 6 and pH 8 varied from 8.31 to 8.48 mg/L O2 and from 8.26 to 8.49 mg/L O2, respectively. These values were higher than the required value of ± 6 mg/L O2 at 22 °C corresponding to a minimal saturation level in air of 70 %.

Temperature:

The temperature of the test solutions fluctuated between 21.5 °C and 22.8 °C and corresponded to the required test conditions of 20 °C – 23 °C

Total organic carbon content (TOC) of test solutions:

The measured TOC of the medium was <1.0 mg/L C, and below the required level of 2.0 mg/L C as laid down in the OECD Test Guidance no.29

Method validation summary (ICP-MS)

Accredited reporting limit (Cr):0.5 µg/L

Working range:0.5 -50µg/L Cr

Linearity check at 50 µg/L:resulted in 51.23 µg/L

Instrument blanks (n=18): -0.002 ± 0.007 µg/L

Recovery of fortified samples: The fortified samples of 1 µg/L total Cr gave a recovery of 108 % and 107 % for the test medium at pH 6 and pH 8, respectively

QC samples from independent certified standard solution (5 µg/L Cr, n=11):4.984 ± 0.04 µg/L

Method validation summary (Ion chromatography)

Reporting limit (Cr6 +):0.05 µg/L

Working range:0.05 µg/L - 5.0 µg/L Cr6+

Calibration solutions:0, 0.05, 0.1, 0.5, 1.0 and 5 µg/L Cr6 +, R2 > 0.99

Recovery of fortified samples: The fortified samples of 0.1 µg/L Cr 6+gave a recovery of 108 % and 74 % for the test medium at pH 6 and pH 8, respectively

Filter adsorption:

Nominal conc.	0.1 μg/L Cr	0.5 μg/L Cr	5 μg/L Cr
Filtr 0.2 repl1	0.108	0.493	5.022
Filtr 0.2 repl2	0.099	0.539	4.890
average	0.103	0.516	4.956
SD	0.006	0.033	0.093

No significant influence of the filter on measured Cr concentrations could be observed.

Conclusions:

The transformation/dissolution test (OECD Series on Testing and Assessment Number 29, 2001) of Dichromium nitride at a loading of 1 mg/L at pH 6 and pH 8 resulted in total Chromium and Cr6+ concentrations below the respective reporting limits (Cr: 0.5 µg/L, Cr6+: 0.05 µg/L) for all measured timepoints (24h, 7d, 28d). Therefore, the extent to which Dichromium nitride can produce soluble available ionic and other metal-bearing species in aqueous media, is limited.