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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:

12 February 2018 to 05 March 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

1995

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

2014

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Key result

Water solubility:

>= 45.3 - <= 220.2 mg/L

Conc. based on:

test mat.

Incubation duration:

7 d

Temp.:

20 °C

pH:

>= 7.77 - <= 9.22

Remarks on result:

other: Solubility was dependent on nominal concentration range of the test material in water and therefore no exact value was determined.

Details on results:

Measurements during Equilibration
- The carbon content of the test material (72.0 %) was used in the calculation of the test material concentration from the measured DOC concentration.
- After the analysis of the sample of day 7, the plateau was considered as reached.

Results
- The measurements on day 7 (flasks 1C and 2 – 5) were included in the calculation of the solubility of the test material in water.
- Linear dependency of solubility on amount of the test material (nominal load) was perceived in the main test 2.
- As solubility was dependent on nominal concentration, no exact value for the solubility of the test material in water can be stated. The solubility range for the tested nominal concentration 100 – 800 mg/L is 45.3 – 220.2 mg/L, 20 ± 0.5 °C (45.3 – 220.2 * 10^-3 kg/m^3 in SI units), corresponding to 24.2 – 45.3 % of the test material relating to the nominal concentration of the test material.

Discussion
- The solubility of the test material in water was determined from the measured concentrations of DOC in the filtrated test solutions.
- Equilibration time can be considered as approx. 7 days. The measurements of flasks 1C and 2 – 5 were included in the calculation of the solubility of the test material in water. Flask 6 was considered as outlier because the measured DOC concentration using 1 000 mg/L nominal concentration was lower than in flask 5 with 800 mg/L nominal concentration.
- The Total carbon content of the test material was determined under non-GLP conditions in the laboratory Mikroanalytisches Labor Pascher (53424 Remagen, Germany) with 72.00 % and the value was used in the calculation of the test material concentration from the measured DOC concentration.
- As solubility was dependent on nominal concentration, no exact value for the solubility of the test material in water can be stated. The solubility range for the tested nominal concentration 100-800 mg/L is 45.3 – 220.2 mg/L, 20 ± 0.5 °C (45.3 – 220.2 * 10^-3 kg/m^3 in SI units), corresponding to 24.2 – 45.3 % of the test material relating to the nominal concentration of the test material.
- No observations arousing doubts concerning the accuracy of the results and the validity of the study were made.

Table 1: Equilibration

Day	Temperature (°C)	pH*	Measured Values DOC (mg/L)	Concentration Test Material (mg/L)	Difference (%)
1	20.0	6-7	74.24	103.1	-
2	20.0	6-7	108.1	150.2	+ 45.7
3	20.0	6-7	116.2	161.4	+ 7.4
3 (blank)	20.0	7	0.5	-	-
4	19.5	6-7	84.5	117.4	n.a.
4	19.5	6-7	92.0	127.8	- 20.8
5	19.5	6-7	93.8	130.3	+ 1.9
6	19.5	6-7	100.1	139.1	+ 6.7
7	19.5	6-7	87.0	120.9	- 13.1

Values in italics (day 4): Measurement was repeated because the difference to day 3 appeared too large. Only the second measurement was used for evaluation Difference [%] is not applicable (n.a.).

* Measured via pH paper.

 

Table 2: Measurements at Plateau

Flask	Temperature (°C)	pH*	Measured Values DOC (mg/L)	Concentration Test Material (mg/L)	Dissolved Part (%)
2	20.5	7.77	32.6	45.3	45.3
3	20.5	8.79	82.4	114.4	38.1
4	20.5	9.22	116.2	161.3	26.9
5	20.5	9.09	158.5	220.2	27.5
6	20.5	8.48	141.1	196.0	19.6

* Measured via calibrated pH meter.

 

Table 3: Measurements Used for Calculation of Solubility

Flask	Measured Concentration of Test Material (mg/L)	Nominal Concentration of Test Material (mg/L)	Dissolved Part (%)
2	453	100	45.3
3	114.4	300	38.1
1C	120.9	500	24.2
4	161.3	600	26.9
5	220.2	800	27.5
6*	196.0	1 000	19.6

*Was considered as outlier and rejected for evaluation because the test material concentration was lower than in flask 5 with lower nominal concentration.

Conclusions:

Under the conditions of this study, as solubility was dependent on nominal concentration, no exact value for the solubility of the test material in water can be stated. The solubility range for the tested nominal concentration 100-800 mg/L is 45.3 – 220.2 mg/L, 20 ± 0.5 °C (45.3 – 220.2 * 10^-3 kg/m^3 in SI units), corresponding to 24.2 – 45.3 % of the test material relating to the nominal concentration of the test material.

Executive summary:

The water solubility of the test material was investigated in accordance with the standardised guidelines OECD 105 and EU Method A.6, under GLP conditions.

The solubility of the test material in water was determined by measurement of dissolved organic carbon (DOC) concentration in the filtrated test solutions using total organic carbon (TOC) analyser. The total carbon (TC) content of the test material 72.00 % was used in the calculation of the test material concentration from the measured DOC concentration.

Six different loading rates of the test material were chosen to study the effect of the loading rate on the measured water solubility: 100, 300, 600, 800, 1 000 mg/L. Three flasks 1A - C with the same loading rate (500 mg/L) were used during equilibration.

Equilibration was monitored by measurements of flasks 1A - C. Due to a difference of less than 15 % in the concentrations on days 6 and 7 and no upward tendency in the last three time points, the final measurement was performed on day 7 as determination from flasks 2 – 6. DOC was measured via TOC analyser in the saturated aqueous solutions.

No Tyndall effect (i.e. a laser beam was not scattered when transmitted through the liquid) could be observed indicating that no colloidal dispersed particles were present.

Under the conditions of this study, as solubility was dependent on nominal concentration, no exact value for the solubility of the test material in water can be stated. At the plateau the solubility range for the tested nominal concentration 100-800 mg/L is 45.3 – 220.2 mg/L, 20 ± 0.5 °C (45.3 – 220.2 * 10^-3 kg/m^3 in SI units), corresponding to 24.2 – 45.3 % of the test material relating to the nominal concentration of the test material.

Description of key information

Under the conditions of this study, as solubility was dependent on nominal concentration, no exact value for the solubility of the test material in water can be stated. The solubility range for the tested nominal concentration 100-800 mg/L is 45.3 – 220.2 mg/L, 20 ± 0.5 °C (45.3 – 220.2 * 10^-3 kg/m^3 in SI units), corresponding to 24.2 – 45.3 % of the test material relating to the nominal concentration of the test material.

Key value for chemical safety assessment

Water solubility:

45.3 mg/L

at the temperature of:

20 °C

Additional information

The water solubility of the test material was investigated in accordance with the standardised guidelines OECD 105 and EU Method A.6, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

The solubility of the test material in water was determined by measurement of dissolved organic carbon (DOC) concentration in the filtrated test solutions using total organic carbon (TOC) analyser. The total carbon (TC) content of the test material 72.00 % was used in the calculation of the test material concentration from the measured DOC concentration.

Six different loading rates of the test material were chosen to study the effect of the loading rate on the measured water solubility: 100, 300, 600, 800, 1 000 mg/L. Three flasks 1A - C with the same loading rate (500 mg/L) were used during equilibration.

Equilibration was monitored by measurements of flasks 1A - C. Due to a difference of less than 15 % in the concentrations on days 6 and 7 and no upward tendency in the last three time points, the final measurement was performed on day 7 as determination from flasks 2 – 6. DOC was measured via TOC analyser in the saturated aqueous solutions.

No Tyndall effect (i.e. a laser beam was not scattered when transmitted through the liquid) could be observed indicating that no colloidal dispersed particles were present.

Under the conditions of this study, as solubility was dependent on nominal concentration, no exact value for the solubility of the test material in water can be stated. At the plateau the solubility range for the tested nominal concentration 100-800 mg/L is 45.3 – 220.2 mg/L, 20 ± 0.5 °C (45.3 – 220.2 * 10^-3 kg/m^3 in SI units), corresponding to 24.2 – 45.3 % of the test material relating to the nominal concentration of the test material.