Reaction mass of heptachromium tricarbide and trichromium dicarbide

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

weight of evidence

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-OES) 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 the respective 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 7.98 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 8.25 to 8.47 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 Trichromium dicarbide 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 Trichromium dicarbide can produce soluble available ionic and other metal-bearing species in aqueous media, is limited.

Reference 2

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: OECD Guideline test

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Type of method:

flask method

Water solubility:

< 0.5 mg/L

Temp.:

30 °C

pH:

6.5 - 7

Remarks on result:

other: (result below detection limit)

Details on results:

The solubility of the test substance in water was calculated from the determined concentration of the element chromium. For all the measurements the solubility was below the quantification limit.

Conclusions:

Interpretation of results (migrated information): other: insoluble
Substance is soluble only in mineral acids. Water solubility value < 0.5 mg/l is based on the limit of quantification determined according to DIN 32645. Reaction mass of heptachromium tricarbide and trichromium dicarbide concentration in water is most likely less than 0.1 mg/l.

Reference 3

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

equivalent or similar 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:

not specified

Remarks:

insufficient documentation

GLP compliance:

not specified

Type of method:

flask method

Remarks:

Polymethylpentene (PMP) vessels

Specific details on test material used for the study:

Powders of "reaction mass of heptachromium tricarbide and trichromium dicarbide" particles (Cr-C, sized less than 40 µm) were supplied by Delachaux,France. The test item referred to as Cr-C in the published research article "Metal release studies of Cr from CrC and CrN in ALF and GST and in the OECD T/D media" (Jiang et al March 27,2011), is a multiconstituent substance: reaction mass of heptachromium tricarbide CAS# 12075-40-0 and trichromium dicarbide CAS# 12012-35-0 (see attached)

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

< 1 µg/L

Element analysed:

Chromium (total)

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

pH = 6

Remarks on result:

other:

Remarks:

Cr concentrations below LOD (1 µg Cr/L)

Type of test:

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

Mean dissolved conc.:

< 1 µg/L

Element analysed:

Chromium (total)

Loading of aqueous phase:

100 mg/L

Incubation duration:

7 d

Test conditions:

pH = 6

Remarks on result:

other:

Remarks:

Cr concentrations below LOD (1 µg Cr/L)

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

< 1 µg/L

Element analysed:

Chromium (total)

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

pH = 8

Remarks on result:

other:

Remarks:

Cr concentrations below LOD (1 µg Cr/L)

All measured total Cr concentrations including blank samples below LOQ/LOD (3 µg Cr/L, LOQ = 3*LOD)

Conclusions:

Transformation/dissolution of the reaction mass of heptachromium tricarbide and trichromium dicarbide at a loading of 100 mg/L, similar to OECD Series on Testing and Assessment No. 29, resulted in dissolved chromium concentrations that were below the Limit of detection (1 µg/L) at pH 6 and pH 8 after 24 h (screening test) and after 168 h at pH 6. Thus, the reaction mass of heptachromium tricarbide and trichromium dicarbide is poorly soluble in environmental media.

Description of key information

Reaction mass of heptachromium tricarbide and trichromium dicarbid is only soluble in mineral acids. The solubility in water is < 0.5 mg/L (i.e. limit of quantification) based on a test according to DIN 32645.

Transformation/dissolution testing (OECD Series on Testing and Assessment Number 29, 2001) of “reaction mass of heptachromium tricarbide and trichromium dicarbide” at a loading of 100 mg/L indicates a poor solubility in environmental media since dissolved chromium concentrations remained below 1 µg/L (i.e. the limit of detection) at pH 6 and pH 8 after 24 h and at pH 6 after 7 days. Additional transformation/dissolution testing (OECD Series on Testing and Assessment Number 29, 2001) of trichromium dicarbide at a loading of 1 mg/L and at pH 6 and pH 8 resulted in chromium concentrations below respecting reporting limits (Cr: 0.5 µg/L, Cr6+: 0.05 µg/L) after 28 days.

Thus, the reaction mass of heptachromium tricarbide and trichromium dicarbide is also poorly soluble in water and environmental media.