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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:

01-11-2019 to 07-05-2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Guideline study performed under GLP. All relevant validity criteria were met.

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

Determination of the water solubility of the test item employing the flask method with slow stirring approach.The decision of the slow stirring method was made due to the test item properties. The test guideline was consistent with OECD Guideline 105 (water solubility) modified according to Letinski et. al. (2002) and OECD TG 123 (2006).

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected: July 2016 ; signature: January 2017

Type of method:

flask method

Water solubility:

0.001 mg/L

Conc. based on:

test mat.

Incubation duration:

125 h

Temp.:

20 °C

pH:

6

Preliminary test

A non-GLP preliminary test was performed to verify the definitive test study design. For this purpose, 1.8 mL test item was applied on top of approx. 1.8 L purified water (18.2 MOhm/cm) with slow stirring at approx. 20 °C (ambient temperature). After stirring over 2 days, aliquots of approx. 15 mL for the first two samplings (exact volume was determined via weight) were taken and mixed with 10% of the volume (nominal 1.5 mL) of cyclohexane for liquid extraction, corresponding to an enrichment factor of 10, and analysed. After another 4 days, 2 additional aliquots of approx. 10 mL (exact volume was determined via weight) were taken, mixed with 100 μL acetone and used for analysis via SPME. The solubility was determined for all 4 samplings (and both analytical methods) to be in the range of 0.000213 mg/L (or 213 ng/L), verifying the usage of the slow stirring method.

 

Definitive test:

The solubility of the test item in double distilled water was determined employing the flask method slow stirring approach at 20 ± 0.5 °C. The water solubility was respectively at pH 6.0:

Table 1.0 - Water Solubility Results

Sampling	Incubation time (1) [h]	Calculated Concentration (2) [ng/L]		Overall
		Replicate 1	Replicate 2
1	72.97	612 #3	569 #3
2	75.83	582 #3	480 #3
3	78.19	558 #3	404 #3
4	96.71	600	482
5	98.93	586	455
6	101.30	724	552
8	119.43	670	633
7	121.77	679	588
9	124.50	744	521
	Mean	667	538	603
	Deviation [%]	27	39	24
	SD [ng/L]	63	66
	CV [%]	9.6	12

(#1) : time after application

(#2) : Exact weight of the external standard taken into account

(#3) : Not included in calculation, as measured values were above the calibration range and no retention sample was available. Dilution was adapted for further samples

Note: The water solubility of the test item was determined at 20 ± 0.5 °C to be 0.000603 mg/L (or 603 ng/L (pH 6.0). The validity criterion of the repeatability (< 30% and ideally < 15%) could not be fully fulfilled. This was deemed to be acceptable, due to the combination of the very low solubility and that the used methodology (slow stirring with liquid extraction of the test item) was the only suitable approach for the determination of the water solubility.

 

Temperatures were kept constant within ± 0.5 °C. The analytical method (GC MS/MS, external standard) for the determination of the test item was validated and tested with satisfactory results in regard to linearity, accuracy, precision and specificity.

Conclusions:

Interpretation of results: insoluble (< 0.1 mg/L)
The test item water solubility was determined to be 0.000603 mg/L (or 603 ng/L) of solution at pH 6.0 and 20.0 ± 0.5 °C

Executive summary:

The water solubility of the test item was determined according to the slow stirring adapted flask method of OECD Method 105 and EU Method A.6 in accordance with GLP. The solubility of the test item inpurified water with resistance 18.2 MΩ/cm (i.e. conductivity: ≤ 0.5 µS/cm) and/or 10 ppb TOCwas determined employing the flask method with slow stirring approach at 20 ± 0.5 °C with incubation at test temperature for at least 72 h (actual: 72.97 hours) before the first sampling. Additionally, two aquatic test media, Elendt-M4 (daphnia) and TG-medium (algae) were used and tested alongside purified water. Details regarding the test for these test systems are given in the full study report. For each test system, nine samplings over 125 h of incubation were performed. The analytical method (GC tandem MS/MS, external standard) for the determination of the test item was validated and tested with satisfactory results in regard to linearity, accuracy, precision and specificity. The mean water solubility (in double distilled water) of the test item was determined to be 0.000603 mg/L (or 603 ng/L) of solution at pH 6.0 and 20.0 ± 0.5 °C.The validity criterion of the repeatability (< 30% and ideally < 15%) could not be fully fulfilled. This was deemed to be acceptable, due to the combination of the very low solubility and that the used methodology (slow stirring with liquid extraction of the test item) was the only suitable approach for the determination of the water solubility.

Description of key information

Water Solubility (slow stir) = 0.000603 mg/L (or 0.603 µg/L) at 20 ± 0.5 °C and pH 6.0, OECD TG 105, 2020

Key value for chemical safety assessment

Water solubility:

0.001 mg/L

at the temperature of:

20 °C

Additional information

Key study : OECD TG 105, 2020 : The water solubility of the test item was determined according to the slow stirring adapted flask method of OECD Method 105 and EU Method A.6 in accordance with GLP. The solubility of the test item inpurified water with resistance 18.2 MΩ/cm (i.e. conductivity: ≤ 0.5 µS/cm) and/or 10 ppb TOCwas determined employing the flask method with slow stirring approach at 20 ± 0.5 °C with incubation at test temperature for at least 72 h (actual: 72.97 hours) before the first sampling. Additionally, two aquatic test media, Elendt-M4 (daphnia) and TG-medium (algae) were used and tested alongside purified water. Details regarding the test for these test systems are given in the full study report. For each test system, nine samplings over 125 h of incubation were performed. The analytical method (GC tandem MS/MS, external standard) for the determination of the test item was validated and tested with satisfactory results in regard to linearity, accuracy, precision and specificity. The mean water solubility (in double distilled water) of the test item was determined to be 0.000603 mg/L (or 603 ng/L) of solution at pH 6.0 and 20.0 ± 0.5 °C.The validity criterion of the repeatability (< 30% and ideally < 15%) could not be fully fulfilled. This was deemed to be acceptable, due to the combination of the very low solubility and that the used methodology (slow stirring with liquid extraction of the test item) was the only suitable approach for the determination of the water solubility.