Reaction mass ofDisodium [1-{[2-(hydroxy-kO)-3,5-dinitrophenyl]diazenyl-kN1}naphthalen-2-olato(2-)-kO][3-(hydroxy-kO)-4-{[2-(hydroxy-kO)naphthalen-1-yl]diazenyl-kN1}-7-nitronaphthalene-1-sulfonato(3-)]chromate(2-) andDisodium [1-{[2-(hydroxy-kO)-3,5-dinitrophenyl]diazenyl-kN2}naphthalen-2-olato(2-)-kO][3-(hydroxy-kO)-4-{[2-(hydroxy-kO)naphthalen-1-yl]diazenyl-kN1}-7-nitronaphthalene-1-sulfonato(3-)]chromate(2-)

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study completion date: 30 September 2015

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 20011/E TE
Physical State/Appearance: Dark blue solid
Batch: 1309023 (China)
Purity: 61.2 %
Expiry: 30 September, 2018
Storage Conditions: Room temperature in the dark.

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

The sample solutions were taken from the waterbath at various times and the pH of each solution recorded.

Estimation method (if used):

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).

Duration:

120 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

1 g/L

Remarks:

Preliminary test

Duration:

120 h

pH:

7

Temp.:

50 °C

Initial conc. measured:

1 g/L

Remarks:

Preliminary test

Duration:

120 h

pH:

9

Temp.:

50 °C

Initial conc. measured:

1 g/L

Remarks:

Preliminary test

Duration:

720 h

pH:

4

Temp.:

50 °C

Initial conc. measured:

1 g/L

Remarks:

Tier 2

Duration:

720 h

pH:

4

Temp.:

60 °C

Initial conc. measured:

1 g/L

Remarks:

Tier 2

Duration:

456 h

pH:

4

Temp.:

70 °C

Initial conc. measured:

1 g/L

Remarks:

Tier 2

Number of replicates:

Two

Positive controls:

no

Negative controls:

no

Preliminary study:

Preliminary pH 4 Test at 50.0 ± 0.5 ºC. The extent of hydrolysis after 120 hours indicated that further tests (Tier 2), conducted at 50 ± 0.5 °C, 60 ± 0.5 °C and 70 ± 0.5 °C, were required to estimate the rate constant and half-life at 25 °C.

Preliminary pH 7 Test at 50.0 ± 0.5 ºC
Less than 10 % hydrolysis after 5 days at 50.0 ± 0.5 °C, equivalent to a half-life greater than 1 year at 25 °C.

Preliminary pH 9 Test at 50.0 ± 0.5 ºC
Less than 10 % hydrolysis after 5 days at 50.0 ± 0.5 °C, equivalent to a half-life greater than 1 year at 25 °C.

Transformation products:

no

pH:

4

Temp.:

25 °C

Hydrolysis rate constant:

> 0 - < 0 h-1

DT50:

> 449 - < 551 d

Type:

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

pH:

7

Temp.:

25 °C

DT50:

> 1 yr

Type:

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

pH:

9

Temp.:

25 °C

DT50:

> 1 yr

Type:

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

Validation

Linearities of the detector response with respect to concentration were assessed over the nominal concentration range of 5 to 150 mg/L. These were satisfactory with correlation coefficients (r) of ≥ 0.998 being obtained.

Identification of Hydrolysis Products – Tier 3

As the test item has been determined to be hydrolytically stable, i.e., a half-life of greater than 1 year at 25 °C, at pH 4, 7 and 9, it was concluded that Tier 3 testing was not required. No significant peaks were observed at the approximate retention time of the test item on analysis of any matrix blank solutions.

Validity criteria fulfilled:

yes

Conclusions:

At pH 4, the rate constant (hr-1) at 25 °C (peak 1) was 5.24 x 10-5. The estimated half life was 551 days.
At pH 4, the rate constant (hr-1) at 25 °C (peak 2) was 6.44 x 10-5. The estimated half life at 25 °C (peak 2) was 449 days.
At pH 7, the estimated half life at 25 °C was >1 year.
At pH 9, the estimated half life at 25 °C was >1 year.

Executive summary:

Assessment of hydrolytic stability was carried out using a procedure designed to be compatible with Method C.7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004. The kinetics of the study has been determined to be consistent with that of a pseudo-first order reaction, as the graphs of log₁₀ concentration versus time are essentially straight lines. No significant peaks were observed at the approximate retention time of the test item on analysis of any matrix blank solutions. The rate constants and half-lives of the test item at 25 °C are:

At pH 4, the rate constant (hr-1) at 25 °C (peak 1) was 5.24 x 10^-5. The estimated half life was 551 days.

At pH 4, the rate constant (hr-1) at 25 °C (peak 2) was 6.44 x 10^-5. The estimated half life at 25 °C (peak 2) was 449 days.

At pH 7, the estimated half life at 25 °C was > 1 year.

At pH 9, the estimated half life at 25 °C was > 1 year.

The FAT 20011/E has been determined to be hydrolytically stable, i.e., a half-life of greater than 1 year at 25 °C, at pH 4, 7 and 9.

Description of key information

Hydrolytic stability assessment of a read-across substance FAT 20011/E was carried out using a procedure designed to be compatible with Method C.7 Abiotic Degradation, Hydrolysis as a Function of pH of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April 2004. The kinetics of the study has been determined to be consistent with that of a pseudo-first order reaction, as the graphs of log₁₀concentration versus time are essentially straight lines. No significant peaks were observed at the approximate retention time of the test item on analysis of any matrix blank solutions. The rate constants and half-lives of the test item at 25 °C are:

At pH 4, the rate constant (hr-1) at 25 °C (peak 1) was 5.24 x 10^-5. The estimated half life was 551 days.

At pH 4, the rate constant (hr-1) at 25 °C (peak 2) was 6.44 x 10^-5. The estimated half life at 25 °C (peak 2) was 449 days.

At pH 7, the estimated half life at 25 °C was > 1 year.

At pH 9, the estimated half life at 25 °C was > 1 year.

The FAT 20011/E has been determined to be hydrolytically stable, i.e., a half-life of greater than 1 year at 25 °C, at pH 4, 7 and 9.

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C