5-[(2,3-dihydro-6-methyl-2-oxo-1H-benzimidazol-5-yl)azo]barbituric acid

Additional information on environmental fate and behaviour

Administrative data

Endpoint:

additional information on environmental fate and behaviour

Remarks:

Dispersion stability in simulated environmental media

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: OECD 318

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

5-[(2,3-dihydro-6-methyl-2-oxo-1H-benzimidazol-5-yl)azo]barbituric acid

EC Number:

276-344-2

EC Name:

5-[(2,3-dihydro-6-methyl-2-oxo-1H-benzimidazol-5-yl)azo]barbituric acid

Cas Number:

72102-84-2

Molecular formula:

C12H10N6O4

IUPAC Name:

5-[(1E)-2-(6-methyl-2-oxo-2,3-dihydro-1H-1,3-benzodiazol-5-yl)diazen-1-yl]-1,3-diazinane-2,4,6-trione

Test material form:

solid: nanoform

Details on test material:

Name of test substance: Pigment Orange 64 - 5-[(2,3-dihydro-6-methyl-2-oxo-1H-benzimidazol-5-yl)azo]barbituric acid
Batch identification: 01256BJ7
Supplier: BASF Colors & Effects
CAS No.: 72102-84-2
Purity: 97.1 %
Date of production: 16.8.2007
Physical state/ appearance: Orange powder
Mass-specific surface area (BET): 20.8 m2/g
TEM (min. Feret): 60.8 nm (D50)

Results and discussion

Any other information on results incl. tables

At any of the time points mentioned in the TG-318, the influence of Ca and pH is critical. Regardless of pH, the pigment is categorized at the 24h-sampling time as “unstable” in 10 mM Ca, representing high water hardness. The same “instable” categorization can be applied for any media at pH 4.

After 6h at pH 7 and higher and 0 or 1 mM Ca, the majority of the samples showed high dispersion stability. Only the sample at pH 7 and 1 mM Ca showed 88.3% stability which should therefore be rated as intermediate-high stability. At high Ca concentrations of 10 mM the stability was generally low regardless of the pH value.

In general two effects can be observed. A pH-dependent effect with low stability at low pH values and high stability at higher pH values and a Ca-dependent effects showing lower stability at higher Ca levels. Regarding the environmental relevance the substance is treated as high stability.

	Ca(NO3)2	Stability after 6h	Standard deviation	Stability after 15h	Standard deviation	Stability after 24h	Standard deviation
	[mM]	[%]	[%]	[%]	[%]	[%]	[%]
pH 4	0	14.1	0.4	8.0	0.6	6.3	0.6
pH 4	1	8.9	0.5	5.4	0.5	4.3	0.2
pH 4	10	8.3	0.5	4.8	0.3	3.8	0.2
.
pH 7	0	99.8	0.1	99.3	0.2	98.0	0.6
pH 7	1	88.3	1.0	41.5	6.0	27.2	4.0
pH 7	10	7.5	0.1	4.2	0.2	3.1	0.2
.
pH 9	0	96.1	0.9	93.8	2.0	91.8	2.1
pH 9	1	99.6	0.2	97.7	0.4	96.3	0.1
pH 9	10	7.7	1.0	4.6	0.6	4.0	0.6

Applicant's summary and conclusion

Executive summary:

The dispersion stability of the pigment is high and depends especially on water hardness and pH. Only in very hard water with 10 mM Ca and/or under acidic conditions, the dispersion stability is low.