Glycollic acid

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

GLP compliance:

yes

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

Individual separate replicates (n=4) were sampled for each pH (4, 7 and 9) and at each sampling interval (i.e. 0 and 5 days).

Buffers:

Buffers (0.05 M) were prepared at pH 4 (500 mL, 0.1 M potassium hydrogen phthalate and 4 mL 0.1 M sodium hydroxide diluted to 1000 mL with water, no pH adjustment), 7 (500 mL, 0.1 M potassium dihydrogen phosphate and 296 mL 0.1 M sodium hydroxide diluted to 1000 mL with water, pH adjusted with 5 N hydrochloric acid) and 9 (500 mL 0.05 M boric acid and 213 mL sodium hydroxide diluted to 1000 mL with water, pH adjusted with 5 N hydrochloric acid). Buffers were sterilised by passing through a 0.2 mm filter.
Treated buffer solutions (250 mL) were prepared at a nominal concentration of 100 mg/L by addition to glycolic acid (25 mg). Individual portions of the treated solutions were transferred into borosilicate glass vials (24 mL) with screw caps that were gravity sterilised by autoclaving for 35 minutes.

Details on test conditions:

The hydrolytic behaviour of glycolic acid (non-radiolabelled) was investigated in sterile aqueous buffer (pH 4, 7 and 9).
Treated buffer solutions (250 mL) were prepared at a nominal concentration of 100 mg/L by addition to glycolic acid (25 mg). Individual portions of the treated solutions were transferred into borosilicate glass vials (24 mL) with screw caps that were sterilised by autoclaving for 35 minutes.

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

78.9 - 104.3 mg/L

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

77.6 - 96.9 mg/L

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

87.8 - 120.4 mg/L

Number of replicates:

4

Positive controls:

no

Negative controls:

no

Statistical methods:

None reported.

Preliminary study:

A nominal concentration of 100 mg/L in aqueous buffer solution was used at a temperature of 50°C. Less than 10% hydrolysis of glycolic acid was observed after 5 days.

Test performance:

Measurements confirmed that temperature, pH and sterility of the treated buffer solutions were maintained over the duration of the study (i.e. 5 days).

Transformation products:

not measured

Details on hydrolysis and appearance of transformation product(s):

The amount of hydrolysis observed, at a temperature of 50°C, at each pH was less than 10% after 5 days which is equivalent to a half life of greater than one year at environmentally relevant temperatures (i.e. 25°C). Consequently glycolic acid is hydrolytically stable at environmentally relevant temperatures.

% Recovery:

113

St. dev.:

39

pH:

4

Temp.:

50 °C

Duration:

5 d

% Recovery:

94

St. dev.:

12

pH:

7

Temp.:

50 °C

Duration:

5 d

% Recovery:

114

St. dev.:

32

pH:

9

Temp.:

50 °C

Duration:

5 d

Key result

Remarks on result:

hydrolytically stable based on preliminary test

Details on results:

At pH 4, the glycolic acid concentration after 5days at 50°C was in the range 74.5 to 127.5 (mean 103.0 +- SD 20.9) mg/L, compared to 78.9 to 104.3 (mean 103.0 +- SD 20.9) mg/L at the start of the study.
At pH 7, the glycolic acid concentration after 5days at 50°C was in the range 68.0 to 81.3 (mean 78.6 +- SD 7.1) mg/L, compared to 77.6 to 96.9 (mean 83.7 +- SD 8.8) mg/L at the start of the study.
At pH 9, the glycolic acid concentration after 5days at 50°C was in the range 108.4 to 150.4 (mean 123.8 +- SD 15.1) mg/L, compared to 87.8 to 120.4 (mean 108.8 +- SD 14.4) mg/L at the start of the study.

The amount of glycolic acid present after 5 days was 113, 94 and 114% of the level determined after 0 days in buffer solutions at pH 4, 7 and 9, respectively.

Validity criteria fulfilled:

yes

Conclusions:

Glycolic acid is stable to hydrolysis at pH 4, 7 and 9 with a half life of greater than 1 year at a temperature of 25°C.

Executive summary:

The hydrolytic behaviour of glycolic acid was investigated in sterile aqueous buffer (pH 4, 7 and 9) according to the OECD 111 guideline. The GLP study was conducted in 2002.

 

In the preliminary study, conducted at a nominal concentration of 100 mg/L in aqueous buffer solution and at a temperature of 50°C, less than 10% hydrolysis of glycolic acid was observed after 5 days. As this corresponds to a half life of greater than 1 year at an environmentally relevant temperature (i.e. 25°) no further testing is necessary.

 

Glycolic acid is stable to hydrolysis at pH 4, 7 and 9 with an estimated half life of greater than 1 year at a temperature of 25°C.

Description of key information

Glycolic acid is stable to hydrolysis.

Additional information

Glycolic acid is stable to hydrolysis at pH 4, 7 and 9 with a half life of greater than 1 year at a temperature of 25°C.