C-M5

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Testing was conducted between 28 March 2007 and 24 April 2007.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do no effect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

UK GLP standards (Schedule 1, Good Laboratory Practice Regulations 1999 (SI 1999/3106 as amended by SI 2004/0994)).

Test material

Reference

Name:

Unnamed

Type:

Constituent

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Radiolabelling:

no

Study design

Analytical monitoring:

yes

Details on sampling:

The buffer solutions were filtered through a 0.2 µm membrane filter to ensure they were sterile before commencement of the test. Also these solutions were subjected to ultrasonication and degassing with nitrogen to minimise dissolved oxygen content.

Preparation of samples:
Sample solutions were prepared at a nominal concentration of 10 g/l in the three buffer solutions.
The test solutions were then split into individual sealed glass vessels for each data point.
The solutions were shielded from light whilst maintained at the test temperature.

Preliminary test:
Sample solutions at pH 4, 7 and 9 were maintained at 50.0 ± 0.5°C for a period of 120 hours.

Analysis of sample solutions:
The sample solutions were taken from the waterbath at various times and the pH of each solution recorded.
The concentration of the sample solution was determined by high performance liquid chromatography (HPLC).

Samples:
Duplicate aliquots (A and B) of sample solution were diluted by a factor of 100 using glass double-distilled water.

Standards:
Duplicate standard solutions of test material were prepared in 1% relevant buffer solution in glass double-distilled water at a nominal concentration of 100 mg/l.

Buffers:

Buffer Solution (pH 4)
Components: Potassium hydrogen phthalte
Concentration (mol dm-3): 0.05

Buffer Solution (pH7)
Components: Disodium hydrogen orthophosphate (anhydrous), Potassium dihydrogen orthophosphate, Sodium chloride
Concentration (mol dm-3): 0.03, 0.02, 0.02

Buffer Solution (pH9)
Components: Disodium tetraborate, Sodium chloride
Concentration (mol dm-3): 0.01, 0.02

The buffer solutions were filtered through a 0.2 µm membrane filter to ensure they were sterile before commencement of the test. Also these solutions were subjected to ultrasonication and degassing with nitrogen to minimise dissolved oxygen content.

Estimation method (if used):

Not used.

Details on test conditions:

Refer to details on sampling and analytical methods.

Duration of test

Duration of test 1

Duration:

120 h

pH:

4

Initial conc. measured:

10 g/L

Duration of test 2

Duration:

120 h

pH:

7

Initial conc. measured:

10 g/L

Duration of test 3

Duration:

120 h

pH:

9

Initial conc. measured:

10 g/L

Number of replicates:

Duplicate aliquots (A and B) of sample solution were diluted by a factor of 100 using glass double-distilled water.

Positive controls:

no

Negative controls:

no

Statistical methods:

Not specified.

Results and discussion

Preliminary study:

The mean peak heights relating to the standard and sample solutions are shown in table 6.2 (please see remarks on results including tables and figures section).

Test performance:

Validation:
The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0 to 200 mg/l. This was satisfactory with a correlation coefficient of 1.00 being obtained.

Transformation products:

not specified

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

Less than 10% hydrolysis after 5 days at 50°C.

Dissipation DT50 of parent compound

Dissipation DT50 of parent compound 1

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Dissipation DT50 of parent compound 2

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Dissipation DT50 of parent compound 3

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Other kinetic parameters:

None.

Details on results:

At pH4, 7 and 9 there was less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.

Any other information on results incl. tables

Table 6.2 - Preliminary test results

Solution	MeanHeight
Standard 100 mg/l	277.173
Standard 100 mg/l	276.847
Initial Sample A, pH 4	275.433
Initial Sample B, pH 4	275.805
2.4 Hour Sample A, pH 4	276.380
2.4 Hour Sample B, pH 4	275.604
Standard 100 mg/l	277.296
Standard 100 mg/l	277.382
Initial Sample A, pH 7	276.798
Initial Sample B, pH 7	273.898
2.4 Hour Sample A, pH 7	275.030
2.4 Hour Sample B, pH 7	276.702
Standard 100 mg/l	276.444
Standard 100 mg/l	276.057
Initial Sample A, pH 9	274.440
Initial Sample B, pH 9	274.769
2.4 Hour Sample A, pH 9	276.263
2.4 Hour Sample B, pH 9	272.834
Standard 101 mg/l	266.033
Standard 102 mg/l	263.087
120 Hour Sample A, pH 4	263.054
120 Hour Sample B, pH 4	262.992
Standard 101 mg/l	261.426
Standard 102 mg/l	264.737
120 Hour Sample A, pH 7	259.836
120 Hour Sample B, pH 7	263.932
Standard 101 mg/l	262.144
Standard 102 mg/l	264.977
120 Hour Sample A, pH 9	264.834
120 Hour Sample B, pH 9	265.466

The test material concentrations at the given time points are shown in the following tables:

Table 6.3        pH 4 at 50.0 ± 0.5ºC

	Time (Hours)
	0	2.4	120
Concentration (g/l)	9.98	9.99	10.1
Log10[concentration (g/l)]	0.999	0.999	1.00
% of initial	-	100	101

Result:             Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.

Table 6.4       pH 7 at 50.0 ± 0.5ºC

		Time (Hours)
		0		2.4		120
Concentration (g/l)		9.95		9.97		10.1
Log10[concentration (g/l)]		0.998		0.999		1.00
% of initial		-		100		101

Result:             Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.

Table 6.5       pH 9 at 50.0 ± 0.5ºC

		Time (Hours)
		0		2.4		120
Concentration (g/l)		9.97		9.96		10.2
Log10[concentration (g/l)]		0.998		0.998		1.01
% of initial		-		100		102

Result:             Less than 10% hydrolysis after 5 days at 50°C, equivalent to a half-life greater than 1 year at 25°C.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The estimated half-life at 25°C of the test material at pH 4, 7 and 9 is greater than 1 year.

Executive summary:

Abiotic Degradation, Hydrolysis as a Function of pH. 

Assessment of hydrolytic stability was carried out using Method C7 of Commission Directive 92/69/EEC, Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004. The results are as follows:

pH	Estimated half-life at 25°C
4	>1 year
7	>1 year
9	>1 year