[No public or meaningful name is available]

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experiment start date - 19 March 2010; Experiment completion date - 31 May 2010; Study completion date - 30 June 2010.

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:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Identification: FAT 40851/A TE
Batch Number: TZ 5891 / BOP 02-09
Purity: 69.9 % all coloured components
Appearance: Orange powder
Expiry Date: July 31, 2014
Storage Conditions: At room temperature at about 20 °C

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products: beginning, 2.4 and 120 hours
- Sampling method: Before and after incubation at each temperature and pH value, 50 μL aliquots of the test solutions at each pH value were analyzed
- Sampling methods for the volatile compounds, if any: not applicable
- Sampling intervals/times for pH measurements: no data
- Sampling intervals/times for sterility check: After the main test at pH 7.0, a sterility test was performed. All samples were found to be negative
- Sample storage conditions before analysis: not applicable
- Other observation, if any (e.g.: precipitation, color change etc.): no observations reported

Buffers:

- Buffer Solution pH 4.0
- Buffer Solution pH 7.0
- Buffer Solution pH 9.0

The buffer solutions used for the tests were sterilized for 25 minutes in an autoclave prior to first use. Nitrogen was passed through the buffer solutions for 5 minutes to reduce oxygen in the solutions. After the main test at pH 7.0, a sterility test was performed. All samples were found to be negative.

Estimation method (if used):

Arrhenius equation

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: 50 mL Erlenmeyer flasks, which were stoppered or sealed with an inert material
- Sterilisation method: All glassware, which must be inert in the pH range applied, was rinsed with sterile buffer. The buffer solutions used for the tests were sterilized for 25 minutes in an autoclave prior to first use.
- Measures to exclude oxygen: Nitrogen was passed through the buffer solutions for 5 minutes in order to reduce oxygen in the solutions.
- If no traps were used, is the test system closed/open: closed
- Is there any indication of the test material adsorbing to the walls of the test apparatus? no observations reported

TEST MEDIUM
- Volume used/treatment: 50 ml
- Kind and purity of water: Milli-Q supply
- Preparation of test medium: For example: 38.5 mg of FAT 40851/A were dissolved in 100 mL of a solvent mixture of water and acetonitrile (50:50; v/v) to prepare a stock solution of 385.0 μg/mL FAT 40851/A. Calculated volumes of this stock solution were diluted with the same solvent mixture to obtain eight standard solutions in the range from 1.155 μg/mL to 115.5 μg/mL FAT 40851/A.
- Renewal of test solution: During and at the end of the test the stability and accuracy of the calibration solution was confirmed by preparing and analyzing a second set of standard solutions, which were prepared accordingly. These solutions were measured in respective to the calibration curve to check the HPLC system during the test.
- Identity and concentration of co-solvent: acetonitrile (50:50 v/v)

OTHER TEST CONDITIONS
- Adjustment of pH: solutions buffered to pH 4.0, 7.0 and 9.0
- Dissolved oxygen: no data reported. Nitrogen was passed through the buffer solutions for 5 minutes to reduce oxygen in the solutions

Duration:

73 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

> 699 180 - < 724 905 other: peak area counts

Duration:

70.85 h

pH:

4

Temp.:

60 °C

Initial conc. measured:

> 701 049 - < 750 171 other: peak area counts

Duration:

8.25 h

pH:

4

Temp.:

70 °C

Initial conc. measured:

> 617 257 - < 618 900 other: peak area counts

Duration:

652.48 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

> 1 430 327 - < 1 437 525 other: peak area counts

Duration:

907.15 h

pH:

7

Temp.:

70 °C

Initial conc. measured:

> 812 560 - < 814 538 other: peak area counts

Duration:

334.98 h

pH:

7

Temp.:

80 °C

Initial conc. measured:

> 787 490 - < 799 818 other: peak area counts

Duration:

652.48 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

> 1 748 700 - < 1 763 968 other: peak area counts

Duration:

44.62 h

pH:

9

Temp.:

70 °C

Initial conc. measured:

> 629 981 - < 630 762 other: peak area counts

Duration:

23.03 h

pH:

9

Temp.:

80 °C

Initial conc. measured:

> 547 710 - < 552 131 other: peak area counts

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Preliminary study:

Incubation Time at 50.0 °C ± 0.1 °C
0 hours 2.4 hours 5 days
A A B A B
pH 4.0 1248153 1093727 12 211620 83
1215215 1088723 10 3224 100
pH 7.0 1430327 1506539 -5 1179720 18
1437525 1441120 0 1102652 23
pH 9.0 1748700 1702416 3 935784 46
1763968 1701447 4 954405 46
A: Peak Area measured [counts]
B: Hydrolyze Reaction [%]

The results of the preliminary test show, that FAT 40851/A TE is not stable at pH 7.0. Therefore the test at 50 °C was prolonged (at pH 7.0 and pH 9.0) or repeated (at pH 4) in the range of 10 to 90 % degradation.

Test performance:

Main Test at pH 4.0, 7.0 and 9.0 (50.0 °C)
The results of the preliminary test show, that FAT 40851/A is not stable at pH 7.0. Therefore the test at 50 °C was prolonged (at pH 7.0 and pH 9.0) or repeated (at pH 4) in the range of 10 to 90 % degradation. The linear plots (ln ct versus t) prove that the hydrolysis reaction is of pseudo first order in the range from 10 % to 90 % hydrolysis at pH 4, pH 7.0 and pH 9.0.

The reaction rate constant k for pH 4.0, pH 7.0 and pH 9.0 was calculated by regression analysis. The half-life time of FAT 40851/A at pH 4.0 and 50.0 °C is 39 hours.
The half-life time of FAT 40851/A at pH 7.0 and 50.0 °C is 1701 hours.
The half-life time of FAT 40851/A at pH 9.0 and 50.0 °C is 402 hours.

However, the calculated half-life time of FAT 40851/A at pH 4.0 seems to be not reliable. The test item is hydrolytically not stable. Following the degradation is quite difficult as the chemical structure of the hydrolysis product(s) is most probably quite similar to the one of the parent compound, resulting in several peaks (during chromatography of the incubated test item solution) that could not be separated sufficiently from each other. The peak area used for evaluating the degradation behavior strongly depends on the way of integration. Additionally, it might be possible that a peak of the degradation product(s) is covered by the peak of the parent compound. As the peak area directly influences the results of the regression of the pseudo first order rate plot, small deviations in peak area heavily impact the calculation of the half life time, e. g. an increase in slope k of 0.00053 results in an increase of t1/2 from 42 hours to 69 hours.

Transformation products:

not measured

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

see "Details on results"

pH:

4

Temp.:

50 °C

Hydrolysis rate constant:

0.018 h-1

DT50:

39 h

Type:

(pseudo-)first order (= half-life)

pH:

4

Temp.:

60 °C

Hydrolysis rate constant:

0.01 h-1

DT50:

73 h

Type:

(pseudo-)first order (= half-life)

pH:

4

Temp.:

70 °C

Hydrolysis rate constant:

0.171 h-1

DT50:

4 h

Type:

(pseudo-)first order (= half-life)

pH:

7

Temp.:

25 °C

Hydrolysis rate constant:

0 h-1

DT50:

15 313 h

Type:

other: calculated using the Arrhenius equation

pH:

7

Temp.:

50 °C

Hydrolysis rate constant:

0 h-1

DT50:

1 701 h

Type:

(pseudo-)first order (= half-life)

pH:

7

Temp.:

70 °C

Hydrolysis rate constant:

0.001 h-1

DT50:

734 h

Type:

(pseudo-)first order (= half-life)

pH:

7

Temp.:

80 °C

Hydrolysis rate constant:

0.004 h-1

DT50:

177 h

Type:

(pseudo-)first order (= half-life)

pH:

9

Temp.:

25 °C

Hydrolysis rate constant:

0 h-1

DT50:

17 309 h

Type:

other: calculated using the Arrhenius equation

pH:

9

Temp.:

50 °C

Hydrolysis rate constant:

0.002 h-1

DT50:

402 h

Type:

(pseudo-)first order (= half-life)

Other kinetic parameters:

pH 9; 70 °C; Reaction rate constant 0.036210 h-1; Half life time: 19 h
pH 9; 80 °C; Reaction rate constant 0.076819 h-1; Half life time: 9 h

Details on results:

TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes
- Anomalies or problems encountered (if yes): none

MAJOR TRANSFORMATION PRODUCTS
Usually, hydrolysis products should be identified using LC-MS or GC-MS. However, this procedure implies sufficient separation of the individual components that are present in the incubated test item solution (i. e. parent compound and hydrolysis products). The chromatography of the incubated test item solution of FAT 40851/A resulted in several peaks that could not be separated sufficiently from each other. Thus, identification of the hydrolysis products was technically not feasible. The chemical structure of the hydrolysis product(s) is most probably quite similar to the one of the parent compound.

MINOR TRANSFORMATION PRODUCTS
no data

MINERALISATION (distinguish between dark and irradiated samples)
- % of applied radioactivity present as CO2 at end of study: not applicable

INDICATION OF UNSTABLE TRANSFORMATION PRODUCTS: no data

VOLATILIZATION (at end of study)
not applicable

UNIDENTIFIED RADIOACTIVITY (at end of study)
not applicable

PATHWAYS OF HYDROLYSIS
not applicable

SUPPLEMENTARY EXPERIMENT (if any): RESULTS: no data

Validity criteria fulfilled:

yes

Conclusions:

pH 4.0:
FAT 40851/A at pH 4.0 was found to be not stable at pH 4.0. However, calculation of the half-life time at 25 °C was not feasible.

pH 7.0:
The main peak of FAT 40851/A at pH 7.0 has a half-life time of 15313 hours (638 days) at 25 °C.

pH 9.0:
The main peak of FAT 40851/A at pH 9.0 has a half-life time of 17309 hours (721 days) at 25 °C.

Executive summary:

The purpose of this study was to determine the hydrolysis behavior of FAT 40851/A in aqueous buffered solutions adjusted to pH 4.0, pH 7.0 and pH 9.0.The study followed the protocol given in Council Regulation (EC) No. 440/2008, 30 May 2008, Part C, Methods for the determination of Ecotoxicity, C.7 “Abiotic Degradation: Hydrolysis as a Function of pH” and OECD Guideline for Testing of Chemicals No. 111, “Hydrolysis as a Function of pH”; adopted April 13, 2004 (only at pH 4.0, pH 7.0 and pH 9.0). The hydrolysis of the test item was performed in a preliminary test at 50.0 °C ± 0.5 °C at each of pH 4.0, pH 7.0 and pH 9.0 and in a main test at 60.0 °C and 70.0 °C at pH 4.0, at 70.0 °C and 80.0 °C at pH 7.0 and at pH 9.0. As FAT 40851/A was not stable at pH 4.0, pH 7.0 and at pH 9.0, further testing was performed at elevated temperatures in order to calculate the rate constant (k25) and the half-life time of the hydrolysis at pH 4.0, pH 7.0, pH 9.0 at 25 °C. The results are summarized below (the values typed in italics were calculated using the Arrhenius equation):

pH	Temperature	Reaction rate constant k	Reaction rate constant k	Half-life time t 1/2	Half-life time t 1/2
	[°C]	[1/hours]	[1/s]	[hours]	[days]
4.0	25	Not feasible	Not feasible	Not feasible	Not feasible
	50	1.7917 x 10-2*	4.9770 x 10-6	39	1.6
	60	9.7599 x 10-3*	2.7111 x 10-6	73	3.0
	70	1.7081 x 10-1*	4.7447 x 10-5	4	0.2
7.0	25	4.53 x 10-5	1.26 x 10-8	15313	638
	50	4.1310 x 10-4*	1.1475 x 10-7	1701	70.9
	70	1.0137 x 10-3*	2.8159 x 10-7	734	30.6
	80	3.9245 x 10-3*	1.0901 x 10-6	177	7.4
9.0	25	4.00 x 10-5	1.11 x 10-8	17309	721
	50	1.7241 x 10-3*	4.7892 x 10-7	402	16.8
	70	3.6210 x 10-2*	1.0058 x 10-5	19	0.8
	80	7.6819 x 10-2*	2.1339 x 10-5	9	0.4

* The tabulated value is the mean of two samples.

 

FAT 40851/A was found to be not stable at pH 4.0. However, the calculation of the half-life time at 25 °C and pH 4.0 was not feasible as the half life times at the different temperatures did not lead to a reasonable result.

Description of key information

The substance is hydrolytically stable at pH 7 and 9, but tends to be hydrolytically unstable in acidic environments tested at pH 4.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

The hydrolysis properties of the test item FAT 40851/A were tested in a valid GLP study in accordance with EU Method C.7. The substance was found to be hydrolytically stable at pH 7 with a predicted half-life of 638 day at 25 °C. The half-life could not be accurately determined at pH 4, but the substance tended to be hydrolytically unstable under acidic conditions. At pH 9, the substance was hydrolytically stable and the predicted half-life at 25 °C was 721 days. It is concluded that FAT 40851/A tends to be hydrolytically stable under relevant environmental conditions with a tendency for less stability in acidic environments.