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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:

08 Apr - 14 May 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Type of method:

flask method

Water solubility:

79.5 g/L

Incubation duration:

>= 24 - <= 72 h

Temp.:

20 °C

Remarks on result:

other: pH not determined

Results

Preliminary Test

The preliminary test at room temperature showed, that the water solubility of the test item was between 169.5 and 1,016.7 g/L. The observations of the preliminary test are summarized in Table 1.

Table 1: Preliminary test for the water solubility

Amount of test item [mg]	Total volume of added water [mL]	Time in ultrasonic bath [min]	Remark
101.67	0.1	--	not dissolved
	0.6	--	dissolved

The solubility of the test item in water at room temperature was estimated to be between 169.5 and 1,016.7 g/L. Due to this result, the flask method was performed.

Main Test (flask method)

For the main test three flasks were prepared with an amount of test item and water, and one flask only with water. After stirring and centrifugation the aqueous phases were dilutedwith double distilled waterand measured by means of HPLC. The solution of each flask has been measured twice. The results of these measurements are shown in Table 2. The values represented in the table are rounded values. The calculation was carried out with the original not rounded values.

Table 2: Results of the flask method

Flask	1a (72 h)	2a (48 h)	3a (24 h)	4a (72 h)
measured value [mg/L]	774.1 / 770.5	794.8 / 791.9	821.8 / 817.1	0 / 0
aliquot of the flask [mL]	1	1	1	1
total volume after dilution [mL]	100	100	100	100
water solubility [g/L]	77.41 / 77.05	79.48 / 79.19	82.18 / 81.71	0 / 0
average water solubility [g/L]	77.23	79.33	81.95	0
mean value of the water solubility [g/L]	79.5			0
standard deviation [g/L]	2.4			--
relative standard deviation [%]	3.0			--

To verify the accuracy of the analytical method freshly prepared standard solutions (prepared with the test item) were measured in between the samples of the flask method. The results of these measurements are shown in Table 3.

Table 3: Measurements of standard solutions

Standard solution (nominal value [mg/L])	Measured value [mg/L]	Repeatability [%]
Ü-1 (650.8)	652.96	100.3
	653.04	100.3
	650.10	99.9
	649.40	99.8
Ü-2 (699.2)	698.91	100.0
	700.43	100.2
	695.36	99.5
	695.10	99.4

The recovery rate of the measured standard solutions was in the range from 99.4 % to 100.3%, which shows a good accuracy of the analytical method.

 

Final Results

According to OECD Test Guideline 105 (1995) and Regulation EC No. 440/2008 Method A.6. the water solubility at 20 °C of the test item DMPSA-K₂ was determined to be:

cS = 79.5 g/L

RSD = 3.0 %

Description of key information

79.5E03 mg/L at 20 °C (flash method, OECD 105)

Key value for chemical safety assessment

Water solubility:

79.5 g/L

at the temperature of:

20 °C