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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
September 2017 to Oct 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Solvay attach a letter which details the consideration taken to update the tonnage ahead of Brexit and to accomodate the delay in receipt of final full report on Hydrolysis from summer 2019 to November 2019.
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Principles of method if other than guideline:
This study is designed to investigate the rate of hydrolysis of the main components of THPS-Urea Co-polymer (THPS and THPS urea adducts) and the formation and decline of potential degradation products (e.g. tris(hydroxymethyl)phosphine oxide (THPO)), in the dark at three pH values (pH 4, 7, and 9).
GLP compliance:
yes
Specific details on test material used for the study:
- Product Name : Phosphonium, tetrakis(hydroxymethyl)-, sulphate (2:1) (salt), polymer with urea
- Acronym THPS-Urea Co-polymer
- CAS number 63502-25-0
- Main components
• Bis[[carbamoylamino)methyl][tris(hydroxymethyl)]phosphonium] sulphate (THPS Urea 1:1 adduct)
• Bis[tetrakis(hydroxymethyl)phosphonium] sulphate (THPS)
• 1,9-dihydroxy-2,2,8,8-tetrakis(hydroxymethyl)-5-oxo-4,6-diaza-2,8-diphosphonianonane sulphate (THPS Urea 2:1 adduct)

- Concentration 68.4 % w/w
- Batch number PLFV22C1
- Physical form Aqueous solution
- pH at 20ºC 5.4
- Expiry date 22/03/2018
- Storage conditions Ambient
- Safety precautions Normal handling procedures for test substance
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
Tier 1:
A preliminary test was carried out to investigate the hydrolysis of THPS-Urea Co-polymer at pH 4, 7 and 9 at 50 ± 0.5°C for a total duration of 5 days. Duplicate samples were removed at zero time and at 5 days.

Tier 2:
For any pH investigated in Tier 1 at which there was > 10% degradation of THPS, THPS Urea adducts after 5 days, definitive tests were performed at three temperatures. Sufficient units were maintained such that duplicate units can be removed and analysed at 0 and a minimum of six additional time-points up to 30 days or until 90% of the THPS and THPS urea adduct(s) have degraded (whichever is reached first). The temperatures and sampling intervals were selected based upon the results from the Tier 1 test with the agreement of the Sponsor. The chosen temperatures and sampling intervals were recorded in the study file.
Estimation method (if used):
The DT50 and DT90 values for THPS and THPS urea adducts will be determined, assuming first order kinetics, according to the FOCUS guidance document on degradation kinetics..
Transformation products:
yes
No.:
#1
Details on hydrolysis and appearance of transformation product(s):
[P(CH2OH)4]+, SO4 - ---> P(CH2OH)3 ---> O=P(CH2OH)3
THPS THP THPO
Key result
pH:
4
Temp.:
20 °C
DT50:
16 d
Key result
pH:
4
Temp.:
50 °C
DT50:
2 d
Key result
pH:
7
Temp.:
50 °C
DT50:
6 d
Key result
pH:
7
Temp.:
20 °C
DT50:
48 d
Details on results:
According to the preliminary results Tier 1, The DT50s were estimated in a very crude way based on the measured levels of THPS by LC-MS/MS.
50ºC
Buffer % after Predicted THPS DT50 base on Tier 1 results (days)
pH 5 days 50ºC 40ºC 30ºC 20ºC 10ºC
4 8 2 4 8 16 32
7 55 6 12 24 48 96
9 0
Conclusions:
- pH4 at 20°C: DT50=16d
- pH4 at 50°C: DT50=3d
- pH7 at 20°C: DT50= 48d
- pH7 at 50°C: DT50= 6d
There were no measurable residues after 5 days at pH 9, it was not possible to predict DT50s therefore we must assume it is very short.
Executive summary:

 This study was designed to investigate the rate of hydrolysis of the main components of THPS-Urea Co-polymer (THPS and THPS urea adducts) and the formation and decline of potential degradation products (e.g. tris(hydroxymethyl)phosphine oxide (THPO)), in the dark at three pH values (pH 4, 7, and 9).

Currently, the study is still on going. only the results of the Preliminary test are available.

The DT50s were estimated in a very crude way based on the measured levels of THPS by LC-MS/MS according to the preliminary results on Tier 1.

 

- pH4 at 20°C: DT50=16d

- pH4 at 50°C: DT50=3d

- pH7 at 20°C: DT50= 48d

- pH7 at 50°C: DT50= 6d

There were no measurable residues after 5 days at pH 9, it was not possible to predict DT50s therefore we must assume it is very short.

 

This endpoint will be upgraded when the final result will be available.

Description of key information

A study was designed to investigate the rate of hydrolysis of the main components of THPS-Urea Co-polymer (THPS and THPS urea adducts) and the formation and decline of potential degradation products (e.g. tris(hydroxymethyl)phosphine oxide (THPO)), in the dark at three pH values (pH 4, 7, and 9).

Currently, the study is still on going. Only the results of the preliminary test are available.

The DT50s were estimated in a very crude way based on the measured levels of THPS by LC-MS/MS according to the preliminary results on Tier 1.

 

- pH4 at 20°C: DT50=16d

- pH4 at 50°C: DT50=3d

- pH7 at 20°C: DT50= 48d

- pH7 at 50°C: DT50= 6d

There were no measurable residues after 5 days at pH 9, it was not possible to predict DT50s therefore we must assume it is very short.

 

This endpoint will be upgraded when the final result will be available.

Key value for chemical safety assessment

Half-life for hydrolysis:
48 d
at the temperature of:
20 °C

Additional information

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