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

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

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
see attached justification

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

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

Qualifier:

according to guideline

Guideline:

other: OECD 318

GLP compliance:

yes (incl. QA statement)

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

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.

Cross-reference 2

Reason / purpose for cross-reference:

data waiving: supporting information

Cross-reference 3

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Principles of method if other than guideline:

The partition coefficient was estimated based on the ratio of the solubilities in n-octanol and in water.
The individual solubilities were determined by the flask method based on the ETAD method which was developed by intensive cooperation with the ETAD (Ecological and Toxicological Association of Dyes and Organic Pigments Manufacturers) and is regarded as acceptable for pigments by authorities.

GLP compliance:

no

Type of method:

flask method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

0

Temp.:

23 °C

Remarks on result:

other: no data on pH value

Details on results:

49 μg/L was found to be the detection limit (LOD) of the method, the quantification limit (LOQ) was defined as 2 times the detection limit; therefore LOQ is 98 μg/L.

The concentration of the pigment in water and in n-octanol was determined by HPLC-UV measurements at two different wavelengths. At both wavelengths no pigment could be detected in water and n-octanol. Regarding calibration at 300 nm a lower limit of Detection LOD and Limit of Quantification LOQ was achieved, therefore these values were chosen for calculation.

Solvent	Average concentration at 300 nm
water	< 98 μg/L
n-octanol	< 98 μg/L

The n-octanol/water partition coefficient can be approximated with the following equation:

Pow = (C_n-octanol/ C_water) = 1.0

Conclusions:

The partition coefficient of test substance was calculated to be log Pow=0 at 23 °C.

Cross-reference 4

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

- Estimated based on individual solubilities:

log Pow= 0 at 23°C.

- Estimated based on fragment method:

log Pow= 0.5 at 25°C

The partition coefficient was estimated based on the ratio of the solubilities in n-octanol and in water.

The individual solubilities were determined by the flask method based on the ETAD method which was developed by intensive cooperation with the ETAD (Ecological and Toxicological Association of Dyes and Organic Pigments Manufacturers) and is regarded as acceptable for pigments by authorities. The concentration was quanitfied by HPLC with UV-Vis absorption.

In addition, a calculation based on fragment method using KOWWIN (v1.68) module of software EPI Suite v.4.11 yielded a log Pow value of 0.5.

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