Nα-acetyl-DL-tryptophan

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 Feb - 06 Mar 2017

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)

Version / remarks:

2004

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

GLP compliance:

yes (incl. QA statement)

Remarks:

Hess. Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany (11 Nov 2014)

Analytical monitoring:

yes

Remarks:

HPLC/UV-VIS

Details on sampling:

- Sampling intervals for the parent/transformation products: Preliminary test (Tier 1): 0 and 5 d
- Sampling method: Aliquots of each flask are taken in a glove box and cooled down.
- Sampling intervals/times for pH measurements: The pH values of the test item solutios were measured at the end of the experiments.

Buffers:

- pH: 4, 7, and 9
- Composition of buffers: pH 4: 21.01 g citric acid monohydrate dissolved in 200 mL sodium hydroxide solution (1 mol/L). This solution was filled up to a volume of 1000 mL with demineralized water. 44 mL of hydrochloric acid (1 mol/L) was added to 560 mL of this solution and filled up to a volume of 1000 mL with demineralized water; pH 7: 13.61 g potassium dihydrogen phosphate was dissolved in 1000 mL demineralized water. 30 mL of sodium hydroxide solution (1 mol/L) was added to 500 mL of this solution and filled up to a volume of 1000 mL with demineralized water; pH 9: 7.46 g potassium chloride and 6.18 g boric acid were dissolved in 1000 mL demineralized water. 21 mL of sodium hydroxide solution (1 mol/L) was added to 500 mL of this solution and filled up to a volume of 1000 mL with demineralized water.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: Volumetric flasks baked out at 110 °C and flooded with nitrogen
- Measures to exclude oxygen: The volumetric flasks are flooded with nitrogen.

TEST MEDIUM
- Volume used/treatment: 50 mL
- Kind and purity of water: Demineralized water (pH 5 - 7)
- Preparation of test medium: Solutions of the test item are prepared by adding 20 mg of the test item to 50 mL of the relevant buffers at pH 4, 7 and 9.

OTHER TEST CONDITIONS
- Adjustment of pH: The pH value of the buffer solutions was adjusted to the respective pH for each hydrolysis temperature.

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

425.9 mg/L

Remarks:

Preliminary test (tier 1)

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

418.6 mg/L

Remarks:

Preliminary test (tier 1)

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

375.5 mg/L

Remarks:

Preliminary test (tier 1)

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

458.1 mg/L

Remarks:

Preliminary test (tier 1)

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

358.7 mg/L

Remarks:

Preliminary test (tier 1)

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

411.7 mg/L

Remarks:

Preliminary test (tier 1)

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Preliminary study:

At pH 4, 7 and 9 less than 10% of the test item hydrolysed within 5 d. Therefore, additional tests (tier 2 and tier 3) were not necessary.

Transformation products:

no

Remarks on result:

hydrolytically stable based on preliminary test

Validity criteria fulfilled:

yes

Description of key information

The substance is hydrolytically stable (OECD 111, Tier 1 test, pH 4 - 9)

Key value for chemical safety assessment

at the temperature of:

50 °C

Additional information

There is one experimental study available, in which the abiotic hydrolysis of N-Acetyl-DL-tryptophan (CAS 87-32-1) was investigated according to OECD guideline 111 and GLP.

A preliminary (Tier 1) test was performed by dissolving 20 mg of the substance in 50 mL of three buffers adjusted to pH 4, 7 and 9, respectively, and incubating at 50 ± 0.5 °C for 5 d. The concentration of the test item was determined at the start and end of the test by HPLC/UV-VIS.

After 5 d less than 10% of the test item hydrolysed at pH 4, 7, and 9 (maximum decomposition: 2.6%). Therefore, the substance is considered hydrolytically stable and additional (Tier 2 and Tier 3) tests were not necessary.