Glycollic acid

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Principles of method if other than guideline:

None described.

GLP compliance:

not specified

Water solubility:

ca. 2 440 other: g/kg H2O

Temp.:

25 °C

Remarks on result:

other: pH not specified

Conclusions:

Glycolic acid was found to be soluble in water at 25°C (water solubility of about 2440 g/kg H2O).

Executive summary:

Glycolic acid was found to be soluble in water at 25°C (water solubility of about 2440 g/kg H2O).

Reference 2

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 January 2021 - 18 August 2021

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

saturation not achieved

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Key result

Water solubility:

> 1 215 g/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

96 h

Temp.:

30 °C

pH:

9

Key result

Water solubility:

> 904 g/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

96 h

Temp.:

20 °C

pH:

9

Key result

Water solubility:

> 805 g/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

96 h

Temp.:

10 °C

pH:

9

Key result

Water solubility:

> 1 246 g/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

96 h

Temp.:

30 °C

pH:

7

Key result

Water solubility:

> 797 g/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

96 h

Temp.:

20 °C

pH:

7

Key result

Water solubility:

> 803 g/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

96 h

Temp.:

10 °C

pH:

7

Key result

Water solubility:

> 1 243 g/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

96 h

Temp.:

30 °C

pH:

5

Key result

Water solubility:

> 832 g/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

96 h

Temp.:

20 °C

pH:

5

Key result

Water solubility:

> 814 g/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

96 h

Temp.:

10 °C

pH:

5

Key result

Water solubility:

> 862 g/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

96 h

Temp.:

10 °C

pH:

ca. 7

Remarks on result:

other: Solvent is LC-MS grade water - it's pH was not determined but assumed to be close to 7

Key result

Water solubility:

> 852 g/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

96 h

Temp.:

20 °C

pH:

ca. 7

Remarks on result:

other: Solvent is LC-MS grade water - it's pH was not determined but assumed to be close to 7

Key result

Water solubility:

> 1 290 g/L

Conc. based on:

test mat. (dissolved fraction)

Incubation duration:

96 h

Temp.:

30 °C

pH:

ca. 7

Remarks on result:

other: Solvent is LC-MS grade water - it's pH was not determined but assumed to be close to 7

Details on results:

Due to issues with the method validation, for the aqueous solubility which gave low recoveries and poor precision, the validation results were not acceptable. It was felt that this was probably due to interferences due to the use of the pH buffers which resulted in changed chromatography for the method. Based on this it was concluded that the analytical method used was not suitable for analysis in buffers.

These issues with the analytical method plus the fact that, for most of the aqueous solubility samples, all the test item had dissolved prior to analysis, suggesting saturation had not been achieved, meant that it was considered that definitive results for water solubility could not be obtained with this method. Based on this aqueous solubility results have been reported as greater than values.

Conclusions:

The solubility of the test substance was found to be greater than >852 g/L in LC-MS grade water at 20°C. The effect of pH was measured using buffer solutions of pH 5, 7, 9. The impact of changing pH was considered limited. At each pH, and also for LC-MS grade water, the effect of temperature was assessed by measured the solubility at 10, 20 and 30 °C. As was to be expected there was an increased solubility at 30 °C but limited difference between 10 and 20 °C results.

Reference 3

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

; EPA OPPTS 830.7840 (Water Solubility)

Deviations:

no

Remarks:

(The study was conducted according to the test guidelines in effect at the time of study conduct.)

GLP compliance:

yes

Type of method:

flask method

Water solubility:

> 300 g/L

Temp.:

22 °C

pH:

4

Water solubility:

> 300 g/L

Temp.:

22 °C

pH:

7

Water solubility:

> 300 g/L

Temp.:

22 °C

pH:

10

Details on results:

purified water, 22°C: solubility > 300 g/L

Solubility Results

Test System	Sample 1 Concentration (g/L)	Sample 2 Concentration (g/L)	Mean Concentration (g/L)
Pure water	761	771	766
pH 4 buffer	496	487	492
pH 7 buffer	374	381	377
pH 10 buffer	340	326	333

Conclusions:

The solubility of glycolic acid >99% was found to be greater than 300 g/L in purified water, pH 4, pH 7 and pH 10 buffer solutions at ambient laboratory temperature (approximately 22°C).

Executive summary:

The solubility of glycolic acid >99% was found to be greater than 300 g/L in purified water, pH 4, pH 7 and pH 10 buffer solutions at ambient laboratory temperature (approximately 22°C).

Description of key information

1000 g/L is used as the key value for Chemical Safety Assessment, as the limit value for the risk assessment model EUSES.

Key value for chemical safety assessment

Water solubility:

1 000 g/L

at the temperature of:

20 °C

Additional information

Two experimental data and one publication are available:

- Water solubility > 852 g/L at 10, 20 a,d 30°C, and pH 5, 7 and 9 (K2; flask; Foster 2021),

- Water solubility > 300 g/L (333 to 766 g/L) at 22°C, and pH 4, 7 and 10 (S1; flask; HLS 2002),

- Water solubility ca 2440 g/kg water at 25°C, corresponding to 1293 g/L (S4; literature, Apelbat 1990).

The Foster study is regarded as the key study, despite restrictions due to issues with the analytical method validation, because of higher interest than the HLS study, based on higher limit value. The Apelbat publication result is consistent with the above data, but no sufficient details were available to assess its reliability.

With regard to risk assessment, as a worst-case, the maximum value of 1000 g/L that can be used by EUSES in CHESAR model was retained as key value for purpose of CSA, rather than the higher experimental limit value. However, the solubility value is so high that it does not impact the relevant RCR calculations (Sewage Treatment Plant and Human via environment only).