Phosphoric acid, mono- and di-C12-18-(even numbered)-alkyl esters, sodium salts

Hydrolysis

Link to relevant study record(s)

Reference

Reference 1

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)

Deviations:

not specified

GLP compliance:

no

Remarks:

Internal Study, no GLP but GLP conform

Specific details on test material used for the study:

Batch: DEH2024962
Appearance: colourless solid (waxy)
Storage: at room temperature in a closed vessel
Date of production: March 14,.2011
Expiry date: March 13, 2013

Radiolabelling:

no

Analytical monitoring:

yes

Remarks:

LC/MS

Details on sampling:

According to the guideline, a preliminary test (Tier 1) was performed at 50°C±0.5°C at pH 4,7,9 and additional at pH 2. Aliquots of each test solution are analysed after 120 hours incubation at 50°C using the LC/MS analytic. ln case of hydrolysis hydrolysis the decrease of the monoester and diester respectively could be detected.

Buffers:

BUFFER SOLUTI0N pH 2
3.80 g Potassium chloride and 1.0 ml Hydrochloric acid 37% (foaming) are added to about 700 ml of water. The solution is adjusted to 1000 ml.
pH measured: 1.78

BUFFER SOLUTI0N pH 4
To 800 ml 0,1 M Acetic Acid 200 ml of 0,1 M Sodium acetate trihydrate solution are added to obtain 1000 ml buffer solution.
pH measured: 3.98

BUFFER S0LUTI0N pH 7
500 ml of 0.1 M Tris-(hydroxylmethyl)-amino methane solution and 466 g 0.1 M Hydrochloric acid are adjusted to 1000 ml.
pH measured: 7.03

BUFFER S0LUTI0N pH 9
3.60 g Di.sodium-tetra borate (Borax) are dissolved in about 700 ml 0f water. The solution is adjusted to 1000 ml.
pH measured: 9.04

Duration:

120 h

Temp.:

50 °C

Remarks:

at pH 2, 4, 7 and 9

Positive controls:

no

Preliminary study:

LC/Ms.chromatograms of a sample of DEH2024962 at pH7after incubation and the solvent, as well as the calibration curves of the Mono- and Diester are availableinappendixes1and 2.
Under our conditions,the retention times of the interesting ester peaks are about 5.82 min.(Monoester)and8.50min.(Diester) respectively. The areas give the amount of esters,which can be calculated according the following equations:

For pH2 and pH4:
Monoester:equation 1)y = 1679.87x-1427.92

Diester:equation 2)Y = 3269.27x-1825.70

For pH7 and pH 9:
Monoester:equation 3)y = 1713.57x-2537.32

Diester:equation 4)Y = 3191.46x-1580.51

The obtained values have to be multiplied by the diluting factor of 4 to give the oncentration of the corresponding ester. The detected amounts(%) are calculated as followed:

Example: Monoester; Sample7; pH7',
y(area) = 7790>7790.00=1713.57x-2537.32
10327.32-1713.57x
x = 6.027mg/L

Amount of Monoester in the sample: 6.027mg/l x4(dilutingfactor)=24.11mg/L

Transformation products:

not measured

% Recovery:

ca. 66.5 - ca. 79.3

pH:

2

Temp.:

50 °C

Duration:

5 d

Remarks on result:

other: lower limit corresponds to receovery % for diesters and upper limit for monoesters

% Recovery:

ca. 85.6 - ca. 92.2

pH:

4

Temp.:

50 °C

Duration:

5 d

Remarks on result:

other: lower limit corresponds to receovery % for monoesters and upper limit for diesters

% Recovery:

ca. 92.2 - ca. 95.4

pH:

7

Temp.:

50 °C

Duration:

5 d

Remarks on result:

other: lower limit corresponds to receovery % for monoesters and upper limit for diesters

% Recovery:

ca. 99.2 - ca. 104.7

pH:

9

Temp.:

50 °C

Duration:

5 d

Remarks on result:

other: lower limit corresponds to receovery % for diesters and upper limit for monoesters

Key result

pH:

4

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Key result

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Details on results:

The detected amounts of mono- and diester after incubation at 50°C for 5 days at pH 4, 7 and 9 were always >90%, except monoester at pH 4 with a detected amount of 85.6%, but this was in the range of uncertainness.

The test substance comprises of about 40% of the diester derivative. The hydrolysis rate is 7.8% at pH 4 (92.2% recovery rate, so the amount of 3.12% diester was hydrolysed. From 3.12% diester, about 2.26% monoester could be formed. The recovered amount of the monoester at pH 4 was 85.6%. If the generated amount of monoester of 2.26% was considered, the remaining recovery rate is 83.3%. But this was in the range of uncertainness.

Due to partial precipitation after incubation, the results are a best case scenario. If all the material had been available for the hydrolysis, the recovery rates would have been slighlty smaller.

The test substance comprises of about 40% of the diester derivative. The hydrolysis rate is 7.8% at pH 4 (92.2% recovery rate, so the amount of 3.12% diester was hydrolysed. From 3.12% diester, about 2.26% monoester could be formed. The recovered amount of the monoester at pH 4 was 85.6%. If the generated amount of monoester of 2.26% was considered, the remaining recovery rate is 83.3%. But this was in the range of uncertainness.

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the study, the test substance is considered to be hydrolytically stable; no hydrolysis occurs. The half-life at 25°C was considered to be >1 year for pH 7 and 9.

Executive summary:

A study was conducted to determine the hydrolysis potential of the test substance at different pH values according to OECD Guideline 411. According to the guideline, a preliminary test (Tier 1) was performed at 50°C±0.5°C at pH 4, 7, 9 and additionally at pH2. Aliquots of each test solutions were analysed to measure the decrease of monoester and diester derivatives after 120 h incubation at 50°C using the LC/MS analytic. No decreases >10% of mono- and diester has been detected at pH 7 and 9. At pH 4, the results were in the range of uncertainness of the measuring method (approximately 10%); at pH 2 the expected hydrolysis was >10%. Therefore, under the conditions of the study, the test substance is considered to be hydrolytically stable; no hydrolysis occurs. The half-life at 25°C was considered to be > 1 year for pH 7 and 9 (Hasemann, 2012).

Reference 2

Endpoint:

hydrolysis

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

due to RA

Justification for type of information:

Refer to the section 13 for details on the read across justification. The study with the read across substance is considered sufficient to fulfil the information requirements as further explained in the provided endpoint summary.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

not specified

GLP compliance:

no

Remarks:

Internal Study, no GLP but GLP conform

Radiolabelling:

no

Analytical monitoring:

yes

Remarks:

LC/MS

Details on sampling:

According to the guideline, a preliminary test (Tier 1) was performed at 50°C±0.5°C at pH 4,7,9 and additional at pH 2. Aliquots of each test solution are analysed after 120 hours incubation at 50°C using the LC/MS analytic. ln case of hydrolysis hydrolysis the decrease of the monoester and diester respectively could be detected.

Buffers:

BUFFER SOLUTI0N pH 2
3.80 g Potassium chloride and 1.0 ml Hydrochloric acid 37% (foaming) are added to about 700 ml of water. The solution is adjusted to 1000 ml.
pH measured: 1.78

BUFFER SOLUTI0N pH 4
To 800 ml 0,1 M Acetic Acid 200 ml of 0,1 M Sodium acetate trihydrate solution are added to obtain 1000 ml buffer solution.
pH measured: 3.98

BUFFER S0LUTI0N pH 7
500 ml of 0.1 M Tris-(hydroxylmethyl)-amino methane solution and 466 g 0.1 M Hydrochloric acid are adjusted to 1000 ml.
pH measured: 7.03

BUFFER S0LUTI0N pH 9
3.60 g Di.sodium-tetra borate (Borax) are dissolved in about 700 ml 0f water. The solution is adjusted to 1000 ml.
pH measured: 9.04

Duration:

120 h

Temp.:

50 °C

Remarks:

at pH 2, 4, 7 and 9

Positive controls:

no

Preliminary study:

LC/Ms.chromatograms of a sample of DEH2024962 at pH7after incubation and the solvent, as well as the calibration curves of the Mono- and Diester are availableinappendixes1and 2.
Under our conditions,the retention times of the interesting ester peaks are about 5.82 min.(Monoester)and8.50min.(Diester) respectively. The areas give the amount of esters,which can be calculated according the following equations:

For pH2 and pH4:
Monoester:equation 1)y = 1679.87x-1427.92

Diester:equation 2)Y = 3269.27x-1825.70

For pH7 and pH 9:
Monoester:equation 3)y = 1713.57x-2537.32

Diester:equation 4)Y = 3191.46x-1580.51

The obtained values have to be multiplied by the diluting factor of 4 to give the oncentration of the corresponding ester. The detected amounts(%) are calculated as followed:

Example: Monoester; Sample7; pH7',
y(area) = 7790>7790.00=1713.57x-2537.32
10327.32-1713.57x
x = 6.027mg/L

Amount of Monoester in the sample: 6.027mg/l x4(dilutingfactor)=24.11mg/L

Transformation products:

not measured

% Recovery:

ca. 66.5 - ca. 79.3

pH:

2

Temp.:

50 °C

Duration:

5 d

Remarks on result:

other: lower limit corresponds to receovery % for diesters and upper limit for monoesters

% Recovery:

ca. 85.6 - ca. 92.2

pH:

4

Temp.:

50 °C

Duration:

5 d

Remarks on result:

other: lower limit corresponds to receovery % for monoesters and upper limit for diesters

% Recovery:

ca. 92.2 - ca. 95.4

pH:

7

Temp.:

50 °C

Duration:

5 d

Remarks on result:

other: lower limit corresponds to receovery % for monoesters and upper limit for diesters

% Recovery:

ca. 99.2 - ca. 104.7

pH:

9

Temp.:

50 °C

Duration:

5 d

Remarks on result:

other: lower limit corresponds to receovery % for diesters and upper limit for monoesters

Key result

pH:

4

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Key result

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Details on results:

The detected amounts of mono- and diester after incubation at 50°C for 5 days at pH 4, 7 and 9 were always >90%, except monoester at pH 4 with a detected amount of 85.6%, but this was in the range of uncertainness.

The test substance comprises of about 40% of the diester derivative. The hydrolysis rate is 7.8% at pH 4 (92.2% recovery rate, so the amount of 3.12% diester was hydrolysed. From 3.12% diester, about 2.26% monoester could be formed. The recovered amount of the monoester at pH 4 was 85.6%. If the generated amount of monoester of 2.26% was considered, the remaining recovery rate is 83.3%. But this was in the range of uncertainness.

Due to partial precipitation after incubation, the results are a best case scenario. If all the material had been available for the hydrolysis, the recovery rates would have been slighlty smaller.

The test substance comprises of about 40% of the diester derivative. The hydrolysis rate is 7.8% at pH 4 (92.2% recovery rate, so the amount of 3.12% diester was hydrolysed. From 3.12% diester, about 2.26% monoester could be formed. The recovered amount of the monoester at pH 4 was 85.6%. If the generated amount of monoester of 2.26% was considered, the remaining recovery rate is 83.3%. But this was in the range of uncertainness.

Validity criteria fulfilled:

yes

Conclusions:

Based on the results of the read across study, the test substance is considered to be hydrolytically stable.

Executive summary:

A study was conducted to determine the hydrolysis potential of the read across substance, mono- and di- C12 PSE, K+, at different pH values according to OECD Guideline 411. According to the guideline, a preliminary test (Tier 1) was performed at 50°C±0.5°C at pH 4, 7, 9 and additionally at pH2. Aliquots of each test solutions were analysed to measure the decrease of monoester and diester derivatives after 120 h incubation at 50°C using the LC/MS analytic. No decreases >10% of mono- and diester has been detected at pH 7 and 9. At pH 4, the results were in the range of uncertainness of the measuring method (approximately 10%); at pH 2 the expected hydrolysis was >10%.The half-life at 25°C was considered to be > 1 year for pH 7 and 9.Therefore, based on the results of the read across study, the test substance is considered to be hydrolytically stable (Hasemann, 2012)

Description of key information

Based on the results of the read across study, the test substance is considered to be hydrolytically stable.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

50 °C

Additional information

A study was conducted to determine the hydrolysis potential of the read across substance, mono- and di- C12 PSE, K+, at different pH values according to OECD Guideline 411. According to the guideline, a preliminary test (Tier 1) was performed at 50°C±0.5°C at pH 4, 7, 9 and additionally at pH2. Aliquots of each test solutions were analysed to measure the decrease of monoester and diester derivatives after 120 h incubation at 50°C using the LC/MS analytic. No decreases >10% of mono- and diester has been detected at pH 7 and 9. At pH 4, the results were in the range of uncertainness of the measuring method (approximately 10%); at pH 2 the expected hydrolysis was >10%. The half-life at 25°C was considered to be > 1 year for pH 7 and 9. Therefore, based on the results of the read across study, the test substance is considered to be hydrolytically stable (Hasemann, 2012).

Based on the results of the read across study, the test substance can be considered to be hydrolytically stable. The presence of higher fatty alcohol content in the test substance is not expected to have a differential impact on the hydrolysis potential, as alcohols are generally resistant to hydrolysis (OECD SIDS, 2006).