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Physical & Chemical properties

Water solubility

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Reference
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
September 17, 2018 - October 05, 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method A.6 (Water Solubility)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
no
GLP compliance:
no
Type of method:
column elution method
Specific details on test material used for the study:
The sample was tested as received. No further preliminary treatment such as drying or milling was performed.
Key result
Water solubility:
< 44 µg/L
Conc. based on:
test mat.
Incubation duration:
ca. 95 h
Temp.:
20 °C
pH:
>= 6.3 - <= 6.5

Table 1: Recovery

All recovery values are calculated from the measured and unrounded concentration values and not from the rounded values given in Table 1. The recovery of the standards indicated a sufficient accuracy of the analytical method.

 Standard  Measured concentration /mg/L % Recovery (mean values
 B1 (c = 0.089 mg/L) 0.089/0.087 98.9
 A3 (c= 0.339 mg/L) 0.350/0.346 102.5
 C1 (c= 0.470 mg/L) 0.442/0.451 95.1

Table 2: Repeatability

The repeatability was checked by measuring standard A1 (c=1.357 mg/L) six-fold. The resulting area was used to calculate the standard deviation and the variation coefficient.

 Measurement No.  Area / mAU*s
 1 620.318 
 2 619.062 
 3 630.208 
 4 624.884 
 5  626.337
 6 624.930 
 Mean value  624.3
 Standard deviation  4.1
 Variation coefficient / % 0.7 

The accuracy of the analytical method was evaluated as sufficient as the variation coefficient of the repeatability measurements was < 2.

Three preliminary tests were carried out with specified amounts of the test item and 100 ml and 500 ml demineralized water, respectively. After each addition of an amount of water, the mixture was stirred for at least 24 hours, and visually checked for any undissolved particles.

Table 3: Results of the preliminary test

 

Amount of test item / mg

 

Total volume of demineralized water / mL

 Appearance of mixture
9.2 100 not dissolved
12.4 500 not dissolved
4.1 500  not dissolved

The preliminary test showed that the water solubility of the test item is < 10 mg/L. According to the preliminary test the water solubility was determined by the column elution method in the main test.

Table 4: Column elution method, column 1 (approximately 12.5 mL/h)

 Fraction No.  V/mL  pH  water solubility /µg/L
20 18.5 6.2 <44
21 18.5   6.3 <44
22 18.5 6.3 <44
23 18.5 6.4 <44
 24 18.5 6.3

<44

The water solubility was found to be below the quantification limit of 44 µg/L.

Table 5: Column elution method, column 2 (approximately 25 mL/h)

 Fraction No.

 V/mL

 pH

 water solubility /µg/L

40

17.0

6.5

<44 

41

17.0

6.3

<44  

 42

16.5

6.4 

<44  

43

16.5

6.5

<44  

44

16.5

6.4

<44  

The water solubility was found to be below the quantification limit of 44 µg/L.

In both columns the concentration of five consecutive fractions was constant within ± 30 %. No increasing or decreasing tendency was observed.

Table 6: Coating check

 

 

Amount of test item used for coating /mg

 

Measured concentration

of test item in eluate /mg/L

Amount of test item eluted / mg

 

 Column 12.5 mL/h

    25.3

0.337/0.340

16.9

 Column 25 mL/h

0.270/0.272

13.5

The coating check was successful. Enough test item remained on the columns. The water solubility cs of the test item was below the quantification limit of 44 µg/L.

Conclusions:
The water solubility of the test item at a temperature of 20 °C was determined using the column elution method. It was found to be below the quantification limit: < 44 µg/L.
Executive summary:

The water solubility of the test item was determined according to OECD 105 and Regulation (EC) No. 440/2008 method A.6 using the column elution method with HPLC analysis. 101.3 mg of the test item were dissolved in 100 mL acetone. For charging the columns in each case 25 mL of the test item solution was added to about 3 g of sea sand and the mixtures were shaken. The solvent was then removed under reduced pressure using a rotary evaporator (40 °C, approx. 20 mbar). The dry residues were placed into the columns of the test apparatus, which have afterwards been filled with water (test temperature: 20 °C; water pH at 23 °C: 6.6). After a swelling time of 2 h pumps were started to rinse the test item coated sand with demineralized water. At the end of the study it was confirmed that residual test item remained on the columns. The residual test item was eluted with 50 mL acetone.

The concentration of the test item was quantified by HPLC. The pH of each sample was recorded. The water solubility of the test item at a temperature of 20°C was found to be below the quantification limit: < 44 µg/L.

Description of key information

The water solubility of the test item at a temperature of 20°C was determined according to the column elution method. It was found to be below the quantification limit: < 44 µg/L.

Key value for chemical safety assessment

Additional information

The water solubility of the test item was determined according to OECD 105 and Regulation (EC) No. 440/2008 method A.6 using the column elution method with HPLC analysis (reference 4.8-1). 101.3 mg of the test item were dissolved in 100 mL acetone. For charging the columns in each case 25 mL of the test item solution was added to about 3 g of sea sand and the mixtures were shaken. The solvent was then removed under reduced pressure using a rotary evaporator (40 °C, approx. 20 mbar). The dry residues were placed into the columns of the test apparatus, which have afterwards been filled with water (test temperature: 20 °C; water pH at 23 °C: 6.6). After a swelling time of 2 h pumps were started to rinse the test item coated sand with demineralized water. At the end of the study it was confirmed that residual test item remained on the columns. The residual test item was eluted with 50 mL acetone. The concentration of the test item was quantified by HPLC. The pH of each sample was recorded. The water solubility of the test item at a temperature of 20°C was found to be below the quantification limit: < 44 µg/L.