Tetrasodium 3,3'-[[6-[(2-hydroxyethyl)amino]-1,3,5-triazine-2,4-diyl]bis[imino(2-methyl-4,1-phenylene)azo]]bisnaphthalene-1,5-disulphonate

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

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)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Remarks:

HPLC

Details on sampling:

Samples were taken and analyzed by HPLC immediately after preparation of the test solutions.

Buffers:

Buffer pH 4 Citric acid/NaOH/NaCl; Fluka, order no.: 33643
Buffer pH 7 KH2PO4/Na2HPO4, Fluka, order no.: 33646
Buffer pH 9 Na2B4O7/HCl, Fluka, order no.: 33648

Details on test conditions:

CALIBRATION:
The test item was used as standard compound for the calibration.

PREPARATION OF A TEST ITEM STOCK SOLUTION:
A stock solution of the test item was prepared by weighing 40.7 mg of the test item in a 50 mL volumetric flask and filling it to the mark with acetonitrile, which results in a final concentration of 700.9 mg/L.

PREPARATION OF THE CALIBRATION SOLUTIONS:
The stock solution was diluted with appropriate volumes to obtain calibration solutions between 35.0 and 140.2 mg/L in acetonitrile/water (1/1; V/V).

PRAPARATION OF THE SOLUTION USED FOR VERIFICATION OF THE SYSTEM SUITABILITY:
47.2 mg of the test item were weighed into a 100 mL volumetric flask and filled up to the mark with acetonitrile to obtain a stock solution of 812.8 mg/L. This stock solution was diluted by the factor of 1:20 to obtain a concentration of 40.6 mg/L. This solution was used for verification of the system suitability before analyzing the test solutions.

PREPARATION OF THE HYDROLYSIS TEST SOLUTIONS:
For each pH separate hydrolysis test solutions were prepared in the corresponding buffer systems. Test item concentrations of approx. 100 mg/L were obtained. Aliquots of the stock solutions were taken without further treatment to prepare individual vials for every test point.

PREPARATION AND PROCEDURE OF THE TEST:
All buffer solutions were filled in glass bottles and purged with N2 for five minutes. Afterwards the buffer solutions were sterilized at 120 °C for 20 minutes. Before the beginning of the tests the solutions are tempered and the temperature was checked. All glassware was purged with N2 before and after filling in the test item and the buffer solutions. The test solutions were overlain with N2.
To prove the sterility of the glass instruments and the test design, sterility tests of each buffer solution were performed at the end of the incubation.

SOLUBILITY AND TEST CONCENTRATION:
According to OECD TG 111 the concentration of the test item should not exceed 0.01 M or half of the saturation concentration of the water solubility.
The water solubility of the test item according to the data of the sponsor was determined to be about 71.3 g/L at a pH of 9.1.
Consequently, the test item was applied as aqueous buffer solution with a concentration of approx. 100 mg/L which fulfills the requirements of OECD 111 [1].
Clear solutions were obtained.
In compliance with OECD 111 no further test with organic solvent additives > 1% (v/v) was performed.

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

110.511 mg/L

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

111.984 mg/L

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

123.21 mg/L

Positive controls:

no

Negative controls:

no

Statistical methods:

Results of the solutions for verification of the peak area repeatability show stability of the chromatographic system. A relative standard deviation of approx. 0.5 % indicates a satisfying repeatability and precision of the method applied to quantify the test item concentrations over the test duration of 5 days. The requirements of OECD 111 are met.
Standard deviation: 0.5374
Relative standard deviation: 0.5485

Transformation products:

no

% Recovery:

98

St. dev.:

0.537

Temp.:

50 °C

Duration:

5 d

Remarks on result:

other: at pH values 4, 7 and 9

pH:

4

Temp.:

50 °C

St. dev.:

0.537

Remarks on result:

other: Overall degradation of the test item after 5 days was less than 10 %, therefore considered to be stable and no half-life time and hydrolysis rate calculated.

pH:

7

Temp.:

50 °C

St. dev.:

0.537

Remarks on result:

other: Overall degradation of the test item after 5 days was less than 10 %, therefore considered to be stable and no half-life time and hydrolysis rate calculated.

pH:

9

Temp.:

50 °C

St. dev.:

0.537

Remarks on result:

other: Overall degradation of the test item after 5 days was less than 10 %, therefore considered to be stable and no half-life time and hydrolysis rate calculated.

Details on results:

RESULTS HYDROLYSIS PH 4, 7 AND 9 AT 50 °C:
The overall degradation of Direct Yellow 86 item at 50 °C at pH 4, 7 and 9 after 5 days was less than 10 %.
Therefore the test item is considered to be stable at 50 °C at pH 4, 7 and 9 and no half-life time and hydrolysis rate were calculated.
No further tests at other temperatures are required for pH 4, 7 and 9.

REPEATABILITY:
Results of the solutions for verification of the peak area repeatability show stability of the chromatographic system. A relative standard deviation of approx. 0.5 % indicates a satisfying repeatability and precision of the method applied to quantify the test item concentrations over the test duration of 5 days. The requirements of OECD 111 are met.

SENSITIVITY:
Regarding the chromatogram of the lowest concentration, taken from calibration measurement of repeatability tests, the analytical method is sufficiently sensitive to quantify test item concentrations down to 10 % or less of the initial concentration used in the hydrolysis experiment.

Remark on blank value

During all determinations and the calibration there was a blank value caused by the analytical system. Due to the fact that this blind value occurs during all measurements as well as during the calibration this has no influence either on the results of the determinations or on the result of this study. Because no abiotic degradation was found there is no reaction constant calculated where a influence would occur.

Validity criteria fulfilled:

yes

Remarks:

Direct Yellow 86 has a suitable water solubility, analytical methods are available, but the purity of Direct Yellow is not > 95% as the substance exhibits a high water content

Conclusions:

The hydrolysis behaviour of Direct Yellow 86 was investigated at 50 °C at pH values of 4, 7 and 9 over a period of five days according to OECD TG 111. Direct Yellow 86 was found to be stable at 50 °C at the pH-values 4,7 and 9. Therefore it can be assumed that the test item is also stable at 25 °C and no half-life times and hydrolysis rates were calculated.

Executive summary:

The tests were performed according to OECD Guidelines for Testing of Chemicals, Section 1 – Physical-Chemical Properties, OECD TG 111, Council Regulation (EC) No 440/2008, Guideline Part C – Methods for the Determination of Ecotoxicity, C.7. “Abiotic Degradation: Hydrolysis as a Function of pH” [1]

The hydrolysis behaviour of Direct Yellow 86 was investigated at 50 °C at pH values of 4, 7 and 9 over a period of five days according to OECD TG 111. The stability was monitored by HPLC analysis using UV-detection. No abiotic degradation of the test item was observed.

Direct Yellow 86 was found to be stable at 50 °C at all three pH-values. Therefore it can be assumed that the test item is also stable at 25 °C and no half-life times and hydrolysis rates were calculated.

Description of key information

The tests were performed according to OECD Guidelines for Testing of Chemicals, Section 1 – Physical-Chemical Properties, OECD TG 111, Council Regulation (EC) No 440/2008, Guideline Part C – Methods for the Determination of Ecotoxicity, C.7. “Abiotic Degradation: Hydrolysis as a Function of pH” [1]

The hydrolysis behaviour of Direct Yellow 86 was investigated at 50 °C at pH values of 4, 7 and 9 over a period of five days according to OECD TG 111. The stability was monitored by HPLC analysis using UV-detection. No abiotic degradation of the test item was observed.

Direct Yellow 86 was found to be stable at 50 °C at all three pH-values. Therefore it can be assumed that the test item is also stable at 25 °C and no half-life times and hydrolysis rates were calculated.