Manganese, 4-[(4-chloro-5-methyl-2-sulfophenyl)azo]-3-hydroxy-2-naphthalenecarboxylic acid complex

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

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:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

other: ETAD guideline ETAD-229

Deviations:

no

Principles of method if other than guideline:

A defined amount of the pigment was transferred to a 100 mL flask with glass stopper and 60 mL of water (deionised, 18.2 MOcm). This was stirred at 70°C for 2 hours and then 72 hours in an air conditioned laboratory (T = 23°C).
The suspension was then centrifuged (10000 rpm, 10 minutes) and filtered once through a standard paper filter, twice through a 0.2 micrometer membrane filter (Millipore) and twice through a 0.025 micrometer filter (Millipore) until a perfectly clear solution was achieved. This procedure was conducted in parallel for a total of 2 water samples and of 2 n-octanol samples.

GLP compliance:

no

Type of method:

flask method

Specific details on test material used for the study:

- Substance type: Organic
- Physical state: Solid (powder)
- Lot/batch No.: HW-08-012
- Expiration date of the lot/batch: January 01, 2017
- Name of test material (as cited in study report): PIGMENT RED 52:2, TKP 50134
- Analytical purity: not available

Key result

Water solubility:

17.4 mg/L

Conc. based on:

test mat. (total fraction)

Incubation duration:

72 h

Temp.:

23 °C

Remarks on result:

other: pH was not determined

Details on results:

The values for the water solubility were: 16.5 (Abs: 0.459), 18.8 (Abs.: 0.535) and 17.2 mg/L (Abs.: 0.489) (average value: 17.4 mg/L).

Conclusions:

The water solubility of test substance was determined to be 17.4 mg/L at 23°C.

Cross-reference 2

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:

2009

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

other: ETAD guideline ETAD-229

Deviations:

no

Principles of method if other than guideline:

A defined amount of the pigment was transferred to a 100 mL flask with glass stopper and 60 mL of water (deionised, 18.2 MOcm). This was stirred at 70°C for 2 hours and then 72 hours in an air conditioned laboratory (T = 23°C).
The suspension was then centrifuged (10000 rpm, 10 minutes) and filtered once through a standard paper filter, twice through a 0.2 micrometer membrane filter (Millipore) and twice through a 0.025 micrometer filter (Millipore) until a perfectly clear solution was achieved. This procedure was conducted in parallel for a total of 2 water samples and of 2 n-octanol samples.

GLP compliance:

no

Type of method:

estimation method (solubility ratio)

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

- Substance type: Organic
- Physical state: Solid (powder)
- Lot/batch No.: HW-08-012
- Expiration date of the lot/batch: January 01, 2017
- Name of test material (as cited in study report): PIGMENT RED 52:2, TKP 50134
- Analytical purity: not available

Analytical method:

other: UV/Vis

Key result

Type:

log Pow

Partition coefficient:

-0.3

Temp.:

23 °C

Remarks on result:

other: pH not determined

Details on results:

Average concentrations in water: 17.4 mg/L
Average concentration in n-octanol: 8.7 mg/L

Conclusions:

The partition coefficient of test substance was estimated to be log Pow = -0.30 at 23°C

Cross-reference 3

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:

2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: OECD 318

GLP compliance:

no

At any of the time points mentioned in the TG-318, the influence of Ca is critical. Regardless of pH, the pigment is not stable in 10 mM Ca, representing high water hardness.

After 6h, the samples showed high dispersion stability in 0 mM Ca at pH 4. The stability in 0 mM and 1 mM Ca at pH 7 and 9 was intermediate althogh much higher in 0 mM Ca.

After 24 hours the stability in 0 mM Ca at pH 4 remained high. The stability in 0 mM Ca at pH 9 remaind intermediate. For the samples at all other conditions the stability was low

 

Table 1: full results of the dispersion stability in the presence of NOM

	Ca(NO3)2	Stability after 6h	Standard deviation	Stability after 15h	Standard deviation	Stability after 24h	Standard deviation
	[mM]	[%]	[%]	[%]	[%]	[%]	[%]
pH 4	0	99.6	0.5	94.5	1.8	92.9	3.1
pH 4	1	0	0	0	0	0	0
pH 4	10	0	0	0	0	0	0
.
pH 7	0	87.4	1.3	75.4	0.9	10.0	0.9
pH 7	1	12.5	1.7	3.7	0.3	2.2	0.2
pH 7	10	4.6	0.7	0.9	0.4	0.2	0.4
.
pH 9	0	86.1	3.8	73.3	2.5	66.1	2.8
pH 9	1	16.2	1.5	5.4	0.3	3.3	0.2
pH 9	10	5.2	0.3	1.4	0.2	0.7	0.1

 

To rationalize the observed dispersion stability, we finally checked the particle size distribution directly in the environmental medium (exact same sample preparation as for the UV/VIS measurements). We applied the NanoDefine method of Analytical Ultracentrifugation. The centrifugation parameters are given in the methods section.

The observed size distributions confirm the moderate agglomeration at 1 mM Ca, pH7, with NOM. If the particles would have been significantly dissolved, no size distribution would be observable at all by this method, which relies on the detection of the movement of particles during centrifugal separation.

Additionally, the centrifugation methods include a determination of the remaining absorption after centrifugation, fully consistent with the conventional determination of the dissolved fraction after centrifugation as recommended by the TG-318. The remaining absorption was measured at ca. 0.18. This is a fraction of 15% of the initial absorption, but actually is close to the LOD of the built-in UV/Vis detector. Considering the LOD, between 0% and 15% of the sample may have been dissolved.

All evidence combined, the results after centrifugation confirm that at least 85% of the observed dispersion stability has to be attributed to the particles, not to dissolution.

 

Executive summary:

The dispersion stability of Pigment Red 52:2 depends on pH and water hardness. The stability in 0 mM Ca at pH 4 is high. The stability in 0 mM Ca at pH 9 is intermediate. For the samples at all other conditions the stability is low