2-{4-[4-[4-fluoro-6-(2-(2-vinylsulfonylethoxy)ethylamino)-1,3,5-triazin-2-ylamino]phenylazo]phenylazo}naphthalene-4,6,8-trisulfonate, trisodium salt

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 June 2001 to 29 June 2001

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)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Identity: FAT 40800/A
Batch number: WP 2/01
Aggregate state at room temperature: Solid / powder
Color: Dark orange
Storage conditions: At room temperature at about 20 °C, away form direct sunlight
Expiration Date: February 14, 2007

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

10 µL aliquots of the test solutions were analysed after incubation without dilution by measuring the UV signal of FAT 40'800/A after HPLC separation of the injected sample solution.

Buffers:

Buffer pH 4, Biphthalate (Baker Art. No. 5657)
Buffer pH 7, Phosphate (Baker Art. No. 5656)
Buffer pH 9, Borate/Potassium chloride/NaOH (Baker Art. No. 7145)

Estimation method (if used):

When it is not practical to determine a rate constant directly at 25°C, the half-life period can usually be estimated using the Arrhenius equation.

Details on test conditions:

STANDARD SOLUTION:
32.35 mg of FAT 40800/A were dissolved in 100 mL acetonitrile/water (50/50; v:v) to prepare a stock solution of 323.5 µg/mL FAT 40800/A. Calculated volumes of this stock solution were diluted with the same eluent to obtain seven standard solutions in the range from 1.6175 µg/mL to 129.4 µg/mL FAT 40800/A. These solutions were used to calibrate the HPLC system.
At the end of the test 32.54 mg test item were weighted and diluted to obtain two solutions with a concentration of 32.54 µg/mL and 97.62 µg/mL FAT 40800/A. These solutions were measured in respective to the calibration curve to check the HPLC-system during the test.

PREPARATION OF TEST SOLUTIONS:
Hydrolysis at 50 °C:
- pH 4.0, Preliminary Test: 10.81 mg of FAT 40800/A were dissolved in 100 mL buffer solution (pH 4.0) to prepare a test solution of 108.1 µg/mL. This solution was treated in an ultrasonic bath for 3 minutes. Two aliquots of this test solution of approximately 50 mL each were transferred into 50 mL Erlenmeyer flasks in order to perform a duplicate test.
-pH 7.0, Preliminary Test: 10.63 mg of FAT 40800/A were dissolved in 100 mL buffer solution (pH 7.0) to prepare a test solution of 106.3 µg/mL. This solution was treated in an ultrasonic bath for 3 minutes. Two aliquots of this test solution of approximately 50 mL each were transferred into 50 mL Erlenmeyer flasks in order to perform a duplicate test.
- pH 9.0, Preliminary Test: 10.91 mg of FAT 40800/A were dissolved in 100 mL buffer solution (pH 9.0) to prepare a test solution of 109.1 µg/mL. This solution was treated in an ultrasonic bath for 3 minutes. Two aliquots of this test solution of approximately 50 mL each were transferred into 50 mL Erlenmeyer flasks in order to perform a duplicate test.
- pH 4.0, Main Test: 10.33 mg of FAT 40800/A were dissolved in 100 mL buffer solution (pH 4.0) to prepare a test solution of 103.3 µg/mL. Two aliquots of this test solution of approximately 50 mL each were transferred into 50 mL Erlenmeyer flasks in order to perform a duplicate test.
- pH 9.0, Main Test: 11.01 mg of FAT 40800/A were dissolved in 100 mL buffer solution (pH 9.0) to prepare a test solution of 110.1 µg/mL. Two aliquots of this test solution of approximately 50 mL each were transferred into 50 mL Erlenmeyer flasks in order to perform a duplicate test.
Hydrolysis at 60 °C
- pH 4.0, Main Test: 11.04 mg of FAT 40800/A were dissolved in 100 mL buffer solution (pH 4.0) to prepare a test solution of 110.4 µg/mL. Two aliquots of this test solution of approximately 50 mL each were transferred into 50 mL Erlenmeyer flasks in order to perform a duplicate test.
- pH 9.0, Main Test: 10.81 mg of FAT 40800/A were dissolved in 100 mL buffer solution (pH 9.0) to prepare a test solution of 108.1 µg/mL. Two aliquots of this test solution of approximately 50 mL each were transferred into 50 mL Erlenmeyer flasks in order to perform a duplicate test.
Hydrolysis at 70 °C
- pH 4.0, Main Test: 10.86 mg of FAT 40800/A were dissolved in 100 mL buffer solution (pH 4.0) to prepare a test solution of 108.6 µg/mL. Two aliquots of this test solution of approximately 50 mL each were transferred into 50 mL Erlenmeyer flasks in order to perform a duplicate test.
- pH 9.0, Main Test:
10.56 mg of FAT 40800/A were dissolved in 100 mL buffer solution (pH 9.0) to prepare a test solution of 105.6 µg/mL. Two aliquots of this test solution of approximately 50 mL each were transferred into 50 mL Erlenmeyer flasks in order to perform a duplicate test.

Number of replicates:

2

Preliminary study:

Further hydrolysis tests were performed at 50 °C, 60 °C and 70 °C in the buffered test solution at pH 4.0 and pH 9.0, due to the instability of the test item found in the preliminary test at 50.0 °C.
At pH 7.0 the test item was found to be stable at 50 °C. Therefore, no further testing was performed at this pH-value.

Transformation products:

not measured

pH:

4

Temp.:

50 °C

Hydrolysis rate constant:

0.049 h-1

DT50:

15 h

Type:

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

Remarks on result:

other: 0.996

pH:

4

Temp.:

60 °C

Hydrolysis rate constant:

0.098 h-1

DT50:

7 h

Type:

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

Remarks on result:

other: 0.997

pH:

4

Temp.:

70 °C

Hydrolysis rate constant:

0.179 h-1

DT50:

4 h

Type:

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

Remarks on result:

other: 0.999

pH:

9

Temp.:

50 °C

Hydrolysis rate constant:

0.017 h-1

DT50:

40 h

Type:

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

Remarks on result:

other: 0.997

pH:

9

Temp.:

60 °C

Hydrolysis rate constant:

0.056 h-1

DT50:

13 h

Type:

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

Remarks on result:

other: 0.999

pH:

9

Temp.:

70 °C

Hydrolysis rate constant:

0.211 h-1

DT50:

3 h

Type:

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

Remarks on result:

other: 0.999

Details on results:

Based on the data obtained at the different temperatures, calculation of the first order rate constant (k25) of the hydrolysis reaction at pH 4.0 and 9.0 was performed according to the Arrhenius equation. The half-life time of the hydrolysis reaction of FAT 40800/A at 25 °C and pH 4.0 was estimated to be 4 days. The half-life time of the hydrolysis reaction of FAT 40800/A at 25 °C and pH 9.0 was estimated to be 65 days.

Results according to the preliminary test

 

Incubation time at 50.0 °C ± 0.1 °C
	0 hours	2.4 hours		5 days
	Initial concentration measured [µg/ml]	Concentration measured [ug/ml]	Hydrolysis reaction [%]	Concentration measured [µg/ml]	Hydrolysis reaction [%]
pH 4.0	110	93	15	< 1.6175*	-100
	109	93	15	< 1.6175*	-100
pH 7.0	113	113	-	105	7
	116	114	2	105	9
pH 9.0	114	111	3	16	86
	114	113	1	15	87

* Value measured below the smallest calibration point of c = 1.6175 µg/ml in this test.

 

 

Results:

pH	Temperature [°C]	Reaction rate constant k [1/hours]	Reaction rate constant k [1/s]	Half-life time 11/2 [hours]
4.0	25	7.51 x 10^-3	2.09 x 10^-6	96
	50	4.86X10^-2	1.35 x10^-5	15
	60	9.81 X10^-2	2.73 x10^-5	7
	70	1.79 x10^-1	4.97 x110^-5	4
9.0	25	4.41 x10^-4	1.23X10^-7	1560
	50	1.70x10^-2	4.73 x10^-6	41
	60	5.63x10^-2	1.56x10^-5	13
	70	2.11 x10^-1	5.87x10^-5	3

 

FAT 40800/A is stable at pH 7.0. Its half-life time is longer than one year at 25 °C.

FAT 40800/A at pH 4.0 has a half-life time of 96 hours ( 4 days) at 25 °C.

FAT 40800/A at pH 9.0 has a half-life time of 1560 hours ( 65 days) at 25 °C.

Validity criteria fulfilled:

yes

Conclusions:

FAT 40800/A is stable at pH 7.0. Its half-life time is longer than one year at 25 °C while at pH 4.0 has a half-life time of 96 hours (4 days) at 25 °C and at pH 9.0 has a half-life time of 1560 hours (65 days) at 25 °C.

Executive summary:

A hydrolysis test was performed following the OECD 111 guideline and EEC C7 guideline under GLP. The hydrolysis of the test item was performed at 50.0 °C ± 0.1 °C at each of pH 4.0, pH 7.0 and pH 9.0. The test substance was found to be stable at pH 7.0 and 50 °C. Therefore no further testing was performed at this pH-value. The test substance was not stable at pH 4.0 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 7.0 and pH 9.0 at 25 °C. Based on the data obtained at the different temperatures, calculation of the first order rate constant (k25) of the hydrolysis reaction at pH 4.0 and 9.0 was performed according to the Arrhenius equation. The test substance is stable at pH 7.0. Its half-life time is longer than one year at 25 °C while at pH 4.0 has a half-life time of 96 hours (4 days) at 25 °C and at pH 9.0 has a half-life time of 1560 hours (65 days) at 25 °C.

Description of key information

The hydrolysis half life of the test substance at 25 °C at pH 7 is more than one year. At environmental conditions, the substance may be considered hydrolytically stable.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

In a GLP-compliant study according to OECD guideline 111, hydrolysis of the test substance was tested at varying temperatures and as a function of pH (RCC, 2001). Based on the results obtained at the various experimental temperatures (50, 60 and 70 °C) at pH (pH 4, 6 and 9), half-life periods of the test substance at 25 °C were calculated to be 96 hours at pH 4 and 1560 hours at pH 9. In a preliminary test, it was already determined that the test substance is stable towards hydrolysis at 50 °C at pH 7 with a calculated half-life at 25 °C of more than one year. Based on these data the substance is considered to be hydrolytically stable under environmental conditions.