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Water solubility

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Reference
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11 July 2018 to 16 July 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method A.6 (Water Solubility)
Version / remarks:
Commission Regulation (EC) No 440/2008 of 30 May 2008 laying down test methods pursuant to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH), Method A.6. “Water Solubility”, Official Journal of the European Union L 142 of 31 May
Deviations:
yes
Remarks:
See "Any other information" for details
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Version / remarks:
Organisation for Economic Co-operation and Development (OECD), OECD Guidelines for Testing of Chemicals, Guideline No. 105, "Water Solubility", adopted July 27, 1995
Deviations:
yes
Remarks:
See "Any other information" for details
GLP compliance:
yes (incl. certificate)
Type of method:
other: theoretical saturation plateau
Specific details on test material used for the study:
No further details specified in the study report.
Key result
Water solubility:
5.82 mg/L
Conc. based on:
test mat.
Temp.:
20 °C
Remarks on result:
other: the mean of the five concordant data of the suspected apparent plateau in each flask
Details on results:
The aim of this Study was to find a theoretical saturation plateau during the course of the sampling time. Considering, that the test item is unstable in water, therefore presumably, two opposing process occur in the test solution: one of them is the dissolution, which is normally a dynamic equilibrium, after the test item reaches the saturation plateau. But, in parallel with the dissolution, a decomposition of the test item also occurs in the test solution (the supposed metabolite appeared in the chromatograms in the course of time). Therefore, for the evaluation of the obtained data, 5 concordant values were chosen from the highest measured concentrations in case of each parallel flask and the mean of these data with the relative standard deviations (RSD%) for each flask was reported. This value is considered to be the best estimate for the water solubility.
Considering the mean of the five concordant data of the suspected apparent plateau in each flask, the water solubility of α,α’-Dichloro-p-xylene was considered to be 5.82 mg/L with 14.6 RSD%at 20°C ± 0.5°C.

Results of the Method Validation

Selectivity

No interfering component was observed

Reinjections repeatability

(7 injections)

CV% ≤1.1%

Linear range

0.01 – 2 µg/mL

Limit of Quantification (LOQ)

0.01 µg/mL

Recovery of the test item from Ultrapure water (10 mg/L)

92%

Precision in Ultrapure water

0.2%

Stability of the samples in the autosampler

At least 45 hours

Stock solution stability at 5 ± 3 °C

(1 mg/mL in ACN)

At least 4 days

 

 

Calibration

Seven concentration levels were used: 0.01, 0.02, 0.05, 0.1, 0.5, 1 and 2 μg/mL. The calibration graph was calculated applying linear regression using 1/concentration as weighting factor.

 

Summary of Standard Curve Parameters

Date

Intercept

Slope

Correlation Coefficient

12 July 2018

-0.185

187

1.0000

13 July 2018

-0.0899

186

1.0000

16 July 2018

0.0829

187

1.0000

 

 

Results of the modified Shake Flask Method

pH of the samples decreased from approximately pH 5.5 to approximately pH 3.5 during the 97 hours sampling time.

Samples were analysed with the above HPLC method.

 

Results of the determination of test item concentrations

Sampling time (hour)

pH

I. flask Measured concentration (mg/L)

pH

II. flask Measured concentration (mg/L)

pH

III. flask Measured concentration (mg/L)

0.5

5.51

2.84

5.47

1.84

5.47

0.570

1

5.65

4.03

5.68

3.47

5.54

0.988

1.5

5.71

4.53

5.61

3.86

5.59

1.32

2

5.61

5.21

5.74

5.61

5.67

1.77

3

5.63

3.31

5.71

5.78

5.75

2.35

4

5.37

5.60

5.30

4.51

5.59

2.97

5

5.41

5.62

5.29

6.15

5.45

3.43

6

5.22

5.70

5.07

7.14

5.36

2.51

7

5.13

5.93

4.96

6.23

5.18

4.21

8

4.96

6.02

4.87

5.77

5.13

4.45

9

4.89

5.94

4.75

7.45

5.14

3.53

24

4.26

5.07

4.18

5.58

4.22

5.30

27

4.17

5.53

4.11

5.30

4.10

4.87

29

4.13

6.64

4.07

5.38

4.13

4.87

31

4.10

5.71

4.08

5.57

4.13

4.95

97

3.48

3.96

3.48

2.89

3.56

0.615

Maximum value (mg/L)

-

6.64

-

7.45

-

5.30

Mean (± RSD%):

6.46 (± 16.9%)

Mean of 5 concordant value*

-

6.01

-

6.55

-

4.89

RSD%

-

6.6

-

10.9

-

6.1

Mean (± RSD%):

5.82 (± 14.6%)

Difference between Max and Min value* (%)

-

16.7

-

22.6

-

15.9

*These values are calculated from the bold signed data

Conclusions:
Considering the mean of the five concordant data of the suspected apparent plateau in each flask, the water solubility of α,α’-Dichloro-p-xylene was considered to be 5.82 mg/L with 14.6 RSD%at 20°C ± 0.5°C.
Executive summary:

The water solubility of α,α’-Dichloro-p-xylene was investigated over the course of time. Considering, that the test item is unstable in water, the aim was to find a theoretical saturation plateau before the significant decomposition of the test item.

Considering the mean of the five concordant data of the apparent saturation plateau, the water solubility of α,α’-Dichloro-p-xylene was considered to be 5.82 mg/L with 14.6 RSD% at 20°C ± 0.5°C.

Description of key information

5.82 mg/L at 20°C ± 0.5°C.

Key value for chemical safety assessment

Water solubility:
5.82 mg/L
at the temperature of:
20 °C

Additional information

The water solubility of α,α’-Dichloro-p-xylene was investigated over the course of time. Considering, that the test item is unstable in water, the aim was to find a theoretical saturation plateau before the significant decomposition of the test item.

Considering the mean of the five concordant data of the apparent saturation plateau, the water solubility of α,α’-Dichloro-p-xylene was considered to be 5.82 mg/L with 14.6 RSD% at 20°C ± 0.5°C.