Trisodium dihydrogen -N,N-[bis[2-[bis(carboxylatomethyl)amino]ethyl]]glycinate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 July -27 July 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

and OECD 111

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch number: 408291

Analytical monitoring:

yes

Remarks:

HPLC

Details on sampling:

Aliquots (1 mL) of a stock solution of Chelest PC-45 in purified water (19 g/L) were added to separate Wheaton vials containing buffer solution (9 mL), which had been purged with nitrogen and pre-equilibrated at test temperature (50 ± 0.5°C). It was necessary to add an increment (30 µL) of 1M hydrochloric acid solution to the pH 4 samples to maintain nominal test pH.

The samples, of nominal concentration 1.9 g/L, were placed in a 50°C waterbath in the dark until sampling was required (immediately, and then after 2.4, 48 and 120 hours).

At each sampling time, two samples were removed from the bath and an aliquot (1 mL) of each was diluted to volume (20 mL) with mobile phase for analysis by high performance liquid chromatography (HPLC).

Buffers:

Buffer solutions were prepared as follows:
pH 4: 0.2M aqueous potassium dihydrogen orthophosphate (220 mL) was mixed with
0.07M aqueous disodium hydrogen orthophosphate dodecahydrate (500 mL) and purified water (1280 mL). The pH was adjusted to 4.0  0.05 with orthophosphoric acid.
pH 7: 0.2M aqueous potassium dihydrogen orthophosphate (500 mL) was mixed with
1M sodium hydroxide (60 mL) and purified water (1440 mL). The pH was measured as
7.0  0.05.
pH 9: 0.1M boric acid in 0.1M aqueous potassium chloride (1000 mL) was mixed with
1M sodium hydroxide (42 mL) and purified water (960 mL). The pH was measured as
9.0  0.05.

Details on test conditions:

The pH values of test solutions and incubation temperature were monitored over the period of the test. The results show that there were no significant changes in pH and temperature with time.

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

1 840 mg/L

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

1 790 mg/L

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

1 850 mg/L

Number of replicates:

Two

Positive controls:

no

Negative controls:

no

Statistical methods:

None

Preliminary study:

The preliminary study showed that at each of pH 4, 7 and 9 and 50  0.5ºC, less than 10% hydrolysis had occurred after 120 hours (5 days), equivalent to a half-life of greater than 1 year under environmental conditions (25°C). No further testing was considered necessary.

Transformation products:

no

Key result

pH:

4

Temp.:

50 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

7

Temp.:

50 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Key result

pH:

9

Temp.:

50 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

           Preliminary test results for hydrolysis of Chelest PC-45

 

	Ct (mg/L)
pH	t0h		t2.4h		t48h		t120h
	Measured	Mean	Measured	Mean	Measured	Mean	Measured	Mean
4	1710, 1960	1840	1740, 1690	1710	1760, 1810	1780	1870, 1850	1860
7	1700, 1880	1790	1830, 1880	1850	1830, 1750	1790	1680, 2070	1880
9	1830, 1860	1850	1820, 1750	1790	1750, 1740	1750	1850, 1770	1810

 

where C_tis the concentration of Chelest PC-45 in solution at time t_h(in hours)

 

Validity criteria fulfilled:

yes

Conclusions:

Chelest PC-45 was determined to be hydrolytically stable under acidic, neutral and basic conditions.

Description of key information

A preliminary study showed that at each of pH 4, 7 and 9 and 50±0.5ºC, less than 10% hydrolysis of the test substance had occurred after 120 hours (5 days), equivalent to a half-life of greater than 1 year under environmental conditions (25°C). No further testing was considered necessary.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C