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Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 November 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

GLP study, conducted to current guidelines.

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

Further details in any other information on materials

GLP compliance:

yes (incl. QA statement)

Type of method:

column elution method

Specific details on test material used for the study:

Substance name RED HF2
Substance type UVCB substance
CAS No. Confidential
Batch No. SR164:1
Purity 100% (UVCB)
Appearance Dark red solid (see certificate of analysis)
Test substance storage Ambient conditions but protected from temperatures below 5°C
Stability under storage Stable under recommended storage conditions
Manufacturing date 12 July 2022
Expiry date 12 July 2027

Key result

Water solubility:

0.284 mg/L

Conc. based on:

test mat.

Loading of aqueous phase:

1.34 g/L

Incubation duration:

1 h

Temp.:

20 °C

Remarks on result:

other: pH not specified.

Key result

Water solubility:

0.284 mg/L

Conc. based on:

test mat.

Loading of aqueous phase:

1.64 g/L

Incubation duration:

2 h

Temp.:

20 °C

Remarks on result:

other: pH not specified

Details on results:

Before introducing the glass beads coated with the test item into the column, approximately 100 mg of glass beads were samples in order to check for the presence of an excess of test item at the beginning of the experiment. They were then extracted with 10 mL of acetone for an HPLC/DAD analysis. The results are presented in any other information on results.

Both systems were considered as in excess of test item since the water solubility estimated is around 1 mg/L

The table in any other information on results presents the concentrations (in mg/L) obtained during the study for both flow rates:

These concentrations are presented as a function of time in illustrations

Some studies have observed higher initial concentrations in the water leaving the column, likely due to loose crystals detaching from the column. The concentrations, however, decreased with recirculation of the water through the column, during which, the detached crystals were most likely retained in the column (6).
The pH controlled with the indicator strips was 5 for all specimen.
The turbidity at the end of the experiment was to 4.67 NFU for the first flow rate and to 2.02 NFU for the second one, meaning that no colloidal matter was present in the water.
The temperature variations were included in the range 19.8°C - 20.1°C.

Equilibrium demonstration
The equilibrium was declared on January 18, 2023 at 11:30 for the first flow rate and on January 20, 2023 at 11:30 for the second flow rate. The following table demonstrates that the equilibrium criteria were valid for each flow rate:

Equilibrium demonstration
The equilibrium was declared on January 18, 2023 at 11:30 for the first flow rate and on January 20, 2023 at 11:30 for the second flow rate. The table in any other information on resuts demonstrates that the equilibrium criteria were valid for each flow rate:

Water solubility calculation
The means of the five last samples before the equilibrium state declaration for each flow rate were:
- 0.251 mg/L for the first flow rate;
- 0.316 mg/L for the second flow rate.
The difference observed between both determinations is 23%, which proves that an acceptable repeatability is obtained (the OECD 105 acceptability criterion for the maximum difference between two tests by the column elution method is 30%).
The RED HF2 solubility in water is given by the mean of the values obtained for both
vessels: 0.284 mg/L.

	First flow rate (23.3 mL/h)	Second flow rate (12 mL/h)
Amount of glass beads coated with the test item sampled for analysis	103.0 mg	109.0 mg
Concentration found in the 10 mL acetone extract	302 mg/L	262 mg/L
Corresponding amount of test item in the system (for 2.5 g of glass beads)	74.1 mg	60.4 mg
Amount lost during the column washing	0.0903 mg	0.0585 mg
Remaining test item amount in the system	74.0 mg	60.3 mg
Theoretical maximum concentration that can be achieved (system volume = 45 mL)	1.64 g/L	1.34 g/L

 

Sampling date	First flow rate 23.3 mL/h	Second flow rate 12 mL/h
01/12/23 8:45	0.574	1.34
01/12/23 13:15	0.573	1.34
01/13/23 9:00	0.400	1.01
01/13/23 13:15	0.372	1.13
01/16/23 7:50	0.238	0.551
01/16/23 11:15	0.248	0.520
01/17/23 7:45	0.264	0.502
01/17/23 11:30	0.261	0.473
01/18/23 7:30	0.244	0.334
01/18/23 11:30	0.239	0.319
01/19/23 7:30	0.266*	0.334
01/19/23 11:30	0.251*	0.336
01/20/23 8:15	0.225*	0.291
01/20/23 11:30	0.222*	0.300

The values marked * were nor used for the equilibrium determination.

 

Criteria	First flow rate	Second flow rate
Maximum difference observed in the 5 last samples Must be < 30%	Min: 0.239 mg/L Max: 0.264 mg/L Difference: 9.9%	Min: 0.291 mg/L Max: 0.336 mg/L Difference: 14.4%
Conclusion	Equilibrium reached	Equilibrium reached

Conclusions:

The RED HF2 solubility in water at 20 ± 0.5 °C, based on the mean of both determinations with the column elution method, was: 0.284 mg/L.

Executive summary:

Introduction                  A study was performed to assess the water solubility of the test item RED HF2 by the column elution method.

Methods                        This method is based on the elution of the test item with water from a micro-column charged with an inert support material (glass beads), previously coated with an excess of the test item.

The water solubility is given by the mass concentration of the eluate when a plateau has been reached as a function of time. The test item concentration was regularly measured by an HPLC-DAD analysis.

Results                          The RED HF2 solubility in water at 20 ± 0.5 °C, based on the mean of both determinations with the column elution method, was: 0.284 mg/L.

Description of key information

The RED HF2 solubility in water at 20 ± 0.5 °C, based on the mean of both determinations with the column elution method, was: 0.284 mg/L.

Key value for chemical safety assessment

Water solubility:

0.284 mg/L

at the temperature of:

20 °C