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Administrative data

Endpoint:
partition coefficient
Type of information:
other: Expert Statement supported by experimental data
Adequacy of study:
key study
Study period:
20 - 24 November 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well documented expert statement supported by experimental data
Cross-reference
Reason / purpose for cross-reference:
reference to other study
Reference
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
02 - 09 August 2017
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:
yes
Remarks:
see principles of method if other than guideline
Qualifier:
according to guideline
Guideline:
EU Method A.6 (Water Solubility)
Version / remarks:
Regulation (EC) No 440/2008
Deviations:
yes
Remarks:
see principles of method if other than guideline
Principles of method if other than guideline:
Due to very high water solubility of the test item, estimated in a preliminary test, a modified TG OECD 105 design was conducted. Instead of equilibrating a large amount of test item with water by stirring over several days and subsequently separating the test item from the saturated solution, water was added in a stepwise procedure to a defined amount of test item until complete dissolution occurred.
GLP compliance:
yes (incl. QA statement)
Remarks:
determination of total phosphorus was performed by a third laboratory under the QA system ISO/IEC 17025 and is therefore excluded from the statement of GLP compliance
Type of method:
flask method
Key result
Water solubility:
>= 379 g/L
Conc. based on:
test mat. (dissolved fraction)
Temp.:
22 °C
pH:
10
Details on results:
Preliminary test
Approximately 1 g of the test item were completely dissolved in 2.4 mL of ultra-pure water indicating a water solubility of about >=420 g/L.

Main test
The results are given in the table in the next section. The water solubility was determined as the mean of the triplicate test assays analysed. As this method does not ensure complete saturation of the solution, it is given as minimum value in mass per volume of solution. The test is satisfactory, if the concentrations of the three vessels do not differ by more than 15%.

Analytical determinations:                                                               

 Test vessel  pH  Analysed concentration A(1) (g/L)   Analysed concentration B(1) (g/L)  Analysed concentration A(2) (g/L)    Analysed concentration B(2) (g/L) Mean (g/L) 

 No. 1

 10

 53.0

52.7

384 

381 

 382

 No. 2

 10

 51.6

52.3

373

378

 376

 No. 3

 10

 52.1

52.2

377

378

 377

         Overall Mean  379

(1) Determined total phosphorous concentrations

(2) Determined test item concentrations

The concentrations of the three vessels differed by 2% (validity criterion given by OECD is met).

Further remarks:

Based on the test item amount used (ca. 1 g) and the volume of ultra-pure water applied (2.3 ml) to achieve complete dissolution, a theoretical solubility of ca. =435 g/l results, which is significantly higher than the water solubility determined in this test. It has to be considered in this case that the final volume of the test item solution is most likely higher than just the 2.3 ml of the ultra-pure water added, due to the very high test item concentrations.

Conclusions:
The water solubility of Disodium beta-glycerophosphate (CAS no. 819-83-0) was determined according to a modified TG OECD 105 design.
The water solubility of the test item at 22°C was >= 379 g/L. The pH of the aqueous solutions was 10.
Executive summary:

The water solubility of the test item Disodium beta-glycerophosphate (CAS no. 819-83-0) was determined according to a modified TG OECD 105 design. To this end, increasing volumes of water were added in a stepwise procedure, to approximately 1 g of the test item at 22 ± 2 °C until complete dissolution, which occurred after addition of 2.3 mL of ultra-pure water. The concentration of test item was subsequently determined by total phosphorous analysis. The determined water solubility of Disodium beta-glycerophosphate is >=379 g/L at pH 10 and at 22 °C.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Version / remarks:
1995
Deviations:
not applicable
Remarks:
not applicable for expert statement
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient - Shake Flask Method)
Version / remarks:
Regulation (EC) No 440/2008
Deviations:
not applicable
Remarks:
not applicable for expert statement
Principles of method if other than guideline:
The objective of this expert statement was to assess the log POW of Disodium beta-glycerophosphate by consideration of both, theoretical as well as experimental data.
Other quality assurance:
ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
Type of method:
flask method
Partition coefficient type:
octanol-water

Test material

Constituent 1
Chemical structure
Reference substance name:
Disodium β-glycerophosphate
EC Number:
212-464-3
EC Name:
Disodium β-glycerophosphate
Cas Number:
819-83-0
Molecular formula:
C3H7O6P.2Na
IUPAC Name:
disodium 2,3-dihydroxypropyl phosphate
impurity 1
Chemical structure
Reference substance name:
Disodium α-glycerophosphate
EC Number:
216-304-3
EC Name:
Disodium α-glycerophosphate
Cas Number:
1555-56-2
Molecular formula:
C3H9O6P.2Na
IUPAC Name:
disodium 2,3-dihydroxypropyl phosphate
impurity 2
Chemical structure
Reference substance name:
Water
EC Number:
231-791-2
EC Name:
Water
Cas Number:
7732-18-5
Molecular formula:
H2O
IUPAC Name:
Oxidane
Test material form:
solid: particulate/powder
Details on test material:
Batch No.: 11769400
Storage: 15-25°C

Study design

Analytical method:
photometric method

Results and discussion

Partition coefficient
Key result
Type:
log Pow
Partition coefficient:
< 0
Temp.:
21 °C
pH:
>= 5 - <= 9
Details on results:
Theoretical considerations
The log POW of Disodium beta-glycerophosphate is estimated to be -6.96 (EPI Suite™ v4.11; KOWWIN v1.68). This predicted value is out of the range of the EPI Suite training set (log POW values >= -5). Nevertheless, it may be used as indication that the log Pow of the test item is very low. Thus, this test is most likely out of the scope of the OECD 107 test (log Pow of -2 to 4) as well as the OECD 117 test (log Pow of 0 to 6) and the OECD 123 test (log Pow >=4) tests.
According to TG OECD 107, this test should be conducted with the non-ionized form and in the environmentally relevant pH range of pH 5 to 9. In the case of Disodium beta-glycerophosphate, the once and twice negatively charged forms predominate in the environmentally relevant range.

Flask method
It was not possible to determine the log POW value of Disodium beta-glycerophosphate, as the determination of the test item concentrations was based on the analysis of total phosphorous, which could only be conducted reliably in the aqueous phase.
However, the experimental data obtained in this study demonstrates that the test item concentrations in the 1-octanol phase must have been negligibly low, as the mass balance calculation based on the aqueous phase alone resulted in recoveries of 104% to 110% (i.e. a log Pow of 0 would correspond to recoveries of about 50%).

Any other information on results incl. tables

Ratio n-octanol:water (v:v)

 Phase

Solvent volume (L) Determined phosphorous concentration (mg/L) Determined test item concentration (mg/L)* Mass balance: Nominal amount of test item(mg)   Mass balance: Total found** (mg)  Mass balance: Recovery rate(%)***
   Ratio 1:4_A

1-Octanol

Aqueous buffer

0.020

0.080  

n.d.

260

n.a.

1881  

144

151

104

   Ratio 1:4_B

1-Octanol

Aqueous buffer

0.020

0.080

n.d.

270

n.a.

1954

144

156

108 

   Ratio 1:9_A

1-Octanol

Aqueous buffer

0.010

0.090

n.d

270

n.a.

1954

162

176

108

   Ratio 1:9_B

1-Octanol

Aqueous buffer

0.010

0.090

n.d.

275

n.a.

1990

 

162 

179

110

   Ratio 1:19_A

1-Octanol

Aqueous buffer

0.005

0.095

n.d.

273

n.a.

1972

 

172

187

109

   Ratio 1:19_B

1-Octanol

Aqueous buffer

 

0.005

0.095

n.d.

268

n.a.

1936

172 

184

107

* Calculated using a total phosphorous content of 13.82% in the test item

** Determined test item concentration in aqueous phase x solvent volume of aqueous phase

*** Percentage of total determined in the aqueous phase / nominal introduced into the system

n.d.: Not determined

n.a.: Not applicable

Further remarks:

Additional evidence for the polarity of the test item and thus a corresponding low log POW value is the water solubility of the test item, which is >=379 g/L (as determined in the water solubility study, see cross-ref). Furthermore, the predicted log POW by EPI Suite™ v4.11 is -6.96 (KOWWIN v1.68).

Applicant's summary and conclusion

Conclusions:
The experimental and theoretical data provided in this expert statement illustrate that Disodium beta-glycerophosphate (CAS no. 819-83-0) most likely has a log POW significantly below zero in the environmentally relevant pH range of 5 to 9.
Executive summary:

It was the aim of this study to assess the log POW of the test item Disodium beta-glycerophosphate (CAS no. 819 -83 -0). To this end, theoretical and experimental data were assembled as presented in this study.

For the experimental part, a test to determine the log POW according to TG OECD 107 was performed: aqueous buffer solution at pH 6.7, 1-octanol and the test item were equilibrated in test vessels by shaking, applying three different volume ratios of the two solvents. The analysis of the test item concentrations was based on total phosphorous, which could only be conducted reliably in the aqueous phase. As the solubility of the test item in 1-octanol is very likely to be poor, no measurements were performed in the 1-octanol phase and consequently no log POW values could be calculated.

The experimental data obtained demonstrate that the test item concentrations in the 1-octanol phase must have been negligibly low, as the mass balance calculation based on the aqueous phase alone resulted in recoveries of 104% to 110% (i.e. a log Pow of 0 would correspond to recoveries of about 50%).

Additional evidence for the polarity of the test item and thus a corresponding low log POW value is the water solubility of the test item, which is >=379 g/L (as determined in the water solubility study). Furthermore, the predicted log POW by EPI Suite™ v4.11 is -6.96 (KOWWIN v1.68).

The experimental and theoretical data provided in this expert statement illustrate that Disodium beta-glycerophosphate most likely has a log POW significantly below zero in the environmentally relevant pH range of 5 to 9.

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