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EC number: 268-655-7 | CAS number: 68132-91-2
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Hydrolysis
Administrative data
Link to relevant study record(s)
- Endpoint:
- hydrolysis
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2019-08-01 to 2020-04-28
- 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)
- Version / remarks:
- 2004
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
- Version / remarks:
- 440/2008
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Radiolabelling:
- no
- Analytical monitoring:
- yes
- Details on sampling:
- Samples were taken at test start (0 h) and at 6-10 spaced time points, normally between 10 and at least 90% of hydrolysis (2 half lives), at each test temperature. After sampling, 100 µL of the sample were diluted with 0.9 mL acetonitrile : methanol : purified water : buffer solution pH 5 (30 : 20 : 37.5 : 12.5), corresponding to a dilution factor of 10, and analyzed.
All test item containing samples were analyzed immediately (if possible less than 30 min until start of analyses, but at least not more than 2.5% of the total study time). - Buffers:
- Test Systems Sterile buffer solutions with pH values 4, 7 and 9
Buffer solutions were prepared from chemicals with analytical grade or better quality following the composition guidance given in “KÜSTER-THIEL, Rechentafeln für die Chemische Analytik” and the OECD Guideline No. 111, respectively, by direct weighing of the buffer components (nominal values are given below). Buffers were purged with nitrogen for 5 min and then the pH was checked to a precision of at least 0.1 at the test temperatures. Buffers were sterilized by filtration through 0.2 µm.
Buffer solution pH 4 0.18 g of sodium hydroxide and 5.7555 g of mono potassium citrate were dissolved in 500 mL ultrapure water.
Buffer solution pH 7 3.854 g of ammonium acetate were dissolved in 500 mL ultrapure water.
Buffer solution pH 9 0.426 g sodium hydroxide, 1.8638 g potassium chloride and 1.5458 g boric acid were dissolved in 500 mL ultrapure water.
Reason for the selection The buffer systems were suitable for their pH values.
Chemical Origin Batch number Purity [%]
NaOH VWR 17F284110 ≥ 97
19F204136 99.3
H3BO3 ROTH 028261978 ≥ 99.5
KCl ROTH 079279869 ≥ 99.5
Ammonium acetate VWR 18C204114 99.2
19D044130 98.1
KH2 Citrate SIGMA-ALDRICH BCBW9888 ≥ 98
Ultrapure water MERCK In-house device - Details on test conditions:
- Preliminary test: pH 4, 7 and 9 at 50 °C for 120 h
Devinitive test: pH 4, 7 and 9 at 20, 30 and 50 °C, respectively - Duration:
- 767 h
- pH:
- 4
- Temp.:
- 20 °C
- Initial conc. measured:
- 7.95 g/L
- Remarks:
- 10 samplings
- Duration:
- 767 h
- pH:
- 4
- Temp.:
- 30 °C
- Initial conc. measured:
- 7.95 g/L
- Remarks:
- 10 samplings
- Duration:
- 768 h
- pH:
- 4
- Temp.:
- 50 °C
- Initial conc. measured:
- 7.95 g/L
- Remarks:
- 10 samplings
- Duration:
- 313 h
- pH:
- 7
- Temp.:
- 20 °C
- Initial conc. measured:
- 7.59 g/L
- Remarks:
- 6 samplings; stopped due to stability after 120 h at 50 °C (criterion for performing the definitive test)
- Duration:
- 314 h
- pH:
- 7
- Temp.:
- 30 °C
- Initial conc. measured:
- 7.59 g/L
- Remarks:
- 6 samplings; stopped due to stability after 120 h at 50 °C (criterion for performing the definitive test)
- Duration:
- 266 h
- pH:
- 7
- Temp.:
- 50 °C
- Initial conc. measured:
- 7.59 g/L
- Remarks:
- 5 samplings; stopped due to stability after 120 h at 50 °C (criterion for performing the definitive test)
- Duration:
- 314 h
- pH:
- 9
- Temp.:
- 20 °C
- Initial conc. measured:
- 7.65 g/L
- Remarks:
- 6 samplings; stopped due to stability after 120 h at 50 °C (criterion for performing the definitive test)
- Duration:
- 314 h
- pH:
- 9
- Temp.:
- 30 °C
- Initial conc. measured:
- 7.65 g/L
- Remarks:
- 6 samplings; stopped due to stability after 120 h at 50 °C (criterion for performing the definitive test)
- Duration:
- 315 h
- pH:
- 9
- Temp.:
- 50 °C
- Initial conc. measured:
- 7.65 g/L
- Remarks:
- 6 samplings; stopped due to stability after 120 h at 50 °C (criterion for performing the definitive test)
- Number of replicates:
- Duplicates per pH and sampling date, single injections.
A third replicate was prepared and immediately frozen after sampling for analyses of possible transformation products. - Positive controls:
- no
- Negative controls:
- yes
- Remarks:
- Buffer solutions (pH value 4, 7 and 9)
- Preliminary study:
- The preliminary test was conducted with a test item concentration of 1.5 g/L in buffer solutions at pH 4, 7 and 9 at 50 °C. For all pH values the definitive test was performed, as a significant reduction (> 10%) of the test item concentration was observed in the preliminary test (50.8% for pH 4, 25.7% for pH 7 and 21.5% for pH 9).
- Test performance:
- The definitive test was conducted with a test item concentration of 7.5 g/L in buffer solutions at pH 4, 7 and 9 at temperatures of 20, 30 and 50 °C. Samples were taken at test start (0 h) and at 6-10 spaced time points until test end. Pure test system (buffer solution at the respective pH value) was analyzed at test start and test end and there was no analytical interference with the test item.
- Transformation products:
- yes
- No.:
- #1
- No.:
- #2
- No.:
- #3
- No.:
- #4
- Details on hydrolysis and appearance of transformation product(s):
- Hydrolysis:
The test item showed a slow hydrolysis rate (> 30 d) for pH 4 at 20 and 30 °C and a moderate hydrolysis (2.4 h ≤ t1/2 ≤ 30 d) for pH 4 at 50 °C.
At pH 7 and 9 no significant reduction of the test item concentration was observed after 266 h at pH 7 and 315 h at pH 9 at 50 °C. Therefore, the definitive study at pH 7 and 9 was stopped and the test item was considered as hydrolytically stable under this condition and a half-life of > 1 year could be assumed for environmental typical temperatures.
Transformation products:
During LC-DAD analysis one (major) transformation product was observed. This transformation product (#3) could not be mass-spectroscopically identified, as no chromatographic signals could be generated for the observed transformation products using LC-MS employing ESI+ ionisation.
At 50 °C three additional (minor) transformation products (#1, #2, #4) were observed during LC-DAD analysis. At 20 and 30 °C only the transformation product #2 was additionally observed. These minor transformation products also could not be mass-spectroscopically identified, as no chromatographic signals could be generated for the observed transformation products using LC-MS employing ESI+ ionisation. - Key result
- pH:
- 4
- Temp.:
- 20 °C
- Hydrolysis rate constant:
- 0 s-1
- DT50:
- 1 077 h
- Type:
- (pseudo-)first order (= half-life)
- Key result
- pH:
- 4
- Temp.:
- 30 °C
- Hydrolysis rate constant:
- 0 s-1
- DT50:
- 880 h
- Type:
- (pseudo-)first order (= half-life)
- Key result
- pH:
- 4
- Temp.:
- 50 °C
- Hydrolysis rate constant:
- 0 s-1
- DT50:
- 314 h
- Type:
- (pseudo-)first order (= half-life)
- Key result
- pH:
- 4
- Temp.:
- 25 °C
- Hydrolysis rate constant:
- 0 s-1
- DT50:
- 944 h
- Type:
- (pseudo-)first order (= half-life)
- Remarks on result:
- other: calculated via Arrhenius calculation
- Details on results:
- The transformation products could not be ionised and therefore not identified by mass-spectroscopy. The tranformation products identified above are based on the retention times of the HPLC and experience of the sponsor with the environmental behaviour of this kind of dyes.
- Validity criteria fulfilled:
- yes
- Conclusions:
- The test item showed a slow hydrolysis rate for pH 4 at 20 and 30 °C with a calculated half-life of 39.3 days at 25°C and a moderate hydrolysis rate for pH 4 at 50 °C.
At pH 7 and 9 no significant reduction of the test item concentration was observed at 50°C and therefore the test item was considered as hydrolytically stable under this condition and a half-life of > 1 year could be assumed for environmental typical temperatures.
One major (T3) and three additional (minor) transformation products (T1, T2, T4) were observed. These transformation products could not be ionised and hence not mass-spectroscopically identified. It is therefore concluded that they consist of copper complex structures similar to the test item itself. - Executive summary:
Hydrolysis as a function of pH was determined according to OECD Guideline No. 111 and Council Regulation (EC) No. 440/2008, Method C.7 for the test item Reactive Blue 160 (batch number: 15741) from 2019 08 01 to 2020-04-28 at the test facility.
Analyses of the test item Reactive Blue 160 were performed via LC DAD on a reversed phase analytical column using the test item as external standard. The analytical method was validated with satisfactory results with regard to linearity, accuracy, precision and specificity.
The preliminary test was conducted with a test item concentration of 1.5 g/L in buffer solutions at pH 4, 7 and 9 at 50 °C. For all pH values the definitive test was performed, as a significant reduction (> 10%) of the test item concentration was observed in the preliminary test.
The definitive test was conducted with a test item concentration of 7.5 g/L in buffer solutions at pH 4, 7 and 9 at temperatures of 20, 30 and 50 °C. Samples were taken at test start (0 h) and at 6 10 spaced time points until test end. Pure test system (buffer solution at the respective pH value) was analyzed at test start and test end and there was no analytical interference with the test item.
At pH 7 and 9 no significant reduction of the test item concentration was observed after 266 h at pH 7 and 315 h at pH 9 at 50 °C. Therefore, the definitive study at pH 7 and 9 was stopped and the test item was considered as hydrolytically stable under this condition and a half-life of > 1 year could be assumed for environmental typical temperatures.
Reaction rate constants, half-lives and activation energies were calculated from the analyzed samples at pH 4 based on a first order reaction kinetics model.
The test item showed a slow hydrolysis rate (> 30 d) for pH 4 at 20 and 30 °C and a moderate hydrolysis (2.4 h ≤ t1/2 ≤ 30 d) for pH 4 at 50 °C.
Classification Scheme based on Hydrolysis Half-life
Classification t ½
fast ≤ 2.4 h
moderate ≥ 2.4 h and ≤ 30 d
slow > 30 d
Reaction Rate Constants and Half-Lives at pH 4
pH 4
20 °C 30 °C 50 °C 25 °C 1)
Reaction rate constant kobs [1/s] 1.79 · 10-7 2.19 · 10-7 6.13 · 10-7 2.04· 10-7
Half-life T½ [h] 1077 880 314 944
Half-life T½ [d] 44.9 36.7 13.1 39.3
Number of data points 11 11 11 EA = 3.35 · 104 J * mol-1
Slope of regression graph significantly non-zero
1) = values calculated via Arrhenius equation
EA = activation energy
During LC-DAD analysis one (major) transformation product was observed. This transformation product (hereinafter labelled as T3) could not be mass-spectroscopically identified, as no chromatographic signals could be generated for the observed transformation products using LC-MS employing ESI+ ionisation.
At 50 °C three additional (minor) transformation products (hereinafter referred as T1, T2, T4) were observed during LC-DAD analysis. At 20 and 30 °C only the transformation product T2 was additionally observed. These minor transformation products also could not be mass-spectroscopically identified, as no chromatographic signals could be generated for the observed transformation products using LC-MS employing ESI+ ionisation.
On basis of the available information (non-ionizability, comparable UV-VIS spectra and small retention time differences) and the chemical sense, three transformation product structures were postulated. The postulated structures are probable candidates for the observed chromatographic transformation product signals.
Reference
Results
Check of the pH-Value
pH-Value of the Test System
measured before application
Intended |
Measured pH‑value |
|||
Preliminary |
Definitive Test |
|||
at 50 °C |
at 20 °C |
at 30 °C |
at 50 °C |
|
4.0 ± 0.1 |
4.033 |
4.056 |
4.061 |
4.062 |
7.0 ± 0.1 |
6.950 |
6.945 |
6.944 |
6.951 |
9.0 ± 0.1 |
9.031 |
9.047 |
9.042 |
9.041 |
Temperature Monitoring
Temperature of the Test System
measured every hour for pH 4, 7 and 9
Test |
Intended Temperature |
Measured Temperature |
|
Mean ± SD |
Min. / Max. |
||
Preliminary |
50.0 ± 0.5 |
50.1 ± 0.01 |
50.0 / 50.1 |
pH 4 |
20.0 ± 0.5 |
20.1 ± 0.04 |
20.0 / 20.2 |
30.0 ± 0.5 |
30.0 ± 0.07 |
29.9 / 30.2 |
|
50.0 ± 0.5 |
50.0 ± 0.02 |
49.9 / 50.1 |
|
pH 7 |
20.0 ± 0.5 |
20.1 ± 0.03 |
20.0 / 20.2 |
30.0 ± 0.5 |
30.0 ± 0.02 |
29.9 / 30.0 |
|
50.0 ± 0.5 |
50.0 ± 0.03 |
49.9 / 50.1 |
|
pH 9 |
20.0 ± 0.5 |
20.1 ± 0.03 |
20.0 / 20.2 |
30.0 ± 0.5 |
30.0 ± 0.02 |
29.9 / 30.1 |
|
50.0 ± 0.5 |
50.0 ± 0.03 |
49.9 / 50.1 |
SD = Standard deviation
The additional manually taken values confirm the results of the automated temperature recording of the datalogger.
Preliminary Test
In the preliminary test more than 10 % of the test item was degraded after 120 hours at pH 4, 7 and pH 9.
Degradation [%] of Reactive Blue 160 at 50 °C after 120 Hours
Hydrolysis Time [hours] |
Degradation [%] |
||
pH 4 |
pH 7 |
pH 9 |
|
120 |
50.8 |
25.7 |
21.5 |
Hydrolysis Results Definitive Test
Hydrolysis Results for the Test Item at pH 4 and 20 °C
Hydrolysis Time [h] |
Concentration [g/L] |
Ln Concentration
|
0.00 |
7.95 |
2.07 |
24.3 |
7.60 |
2.03 |
94.6 |
7.69 |
2.04 |
143 |
8.04 |
2.08 |
191 |
7.61 |
2.03 |
264 |
7.45 |
2.01 |
312 |
7.63 |
2.03 |
361 |
7.78 |
2.05 |
434 |
7.36 |
2.00 |
504 |
7.52 |
2.02 |
767 |
4.02 |
1.39 |
Hydrolysis Results for the Test Item at pH 4 and 30 °C
Hydrolysis Time [h] |
Concentration [g/L] |
Ln Concentration
|
0.00 |
7.95 |
2.07 |
24.7 |
7.52 |
2.02 |
94.9 |
7.72 |
2.04 |
143 |
7.88 |
2.06 |
191 |
7.72 |
2.04 |
265 |
7.20 |
1.97 |
313 |
7.44 |
2.01 |
362 |
7.41 |
2.00 |
434 |
7.04 |
1.95 |
505 |
7.14 |
1.97 |
767 |
3.57 |
1.27 |
Hydrolysis Results for the Test Item at pH 4 and 50 °C
Hydrolysis Time [h] |
Concentration [g/L] |
Ln Concentration
|
0.00 |
7.95 |
2.07 |
25.3 |
7.36 |
2.00 |
95.9 |
6.61 |
1.89 |
144 |
6.31 |
1.84 |
192 |
5.57 |
1.72 |
265 |
4.93 |
1.60 |
313 |
4.64 |
1.53 |
362 |
4.11 |
1.41 |
435 |
3.65 |
1.29 |
505 |
3.40 |
1.22 |
768 |
1.23 |
0.206 |
Hydrolysis Results for the Test Item at pH 7 and 20 °C
Hydrolysis Time [h] |
Concentration [g/L] |
Ln Concentration
|
0.00 |
7.59 |
2.03 |
25.2 |
7.66 |
2.04 |
95.8 |
7.71 |
2.04 |
143 |
8.08 |
2.09 |
192 |
7.77 |
2.05 |
265 |
7.39 |
2.00 |
313 |
7.74 |
2.05 |
Stopped, due to stability after 120 h at 50 °C (criteria for performing the definitive test)
Hydrolysis Results for the Test Item at pH 7 and 30 °C
Hydrolysis Time [h] |
Concentration [g/L] |
Ln Concentration
|
0.00 |
7.59 |
2.03 |
25.6 |
7.48 |
2.01 |
96.0 |
7.56 |
2.02 |
144 |
7.92 |
2.07 |
192 |
7.84 |
2.06 |
266 |
7.38 |
2.00 |
314 |
7.66 |
2.04 |
Stopped, due to stability after 120 h at 50 °C (criteria for performing the definitive test)
Hydrolysis Results for the Test Item at pH 7 and 50 °C
Hydrolysis Time [h] |
Concentration [g/L] |
Ln Concentration
|
0.00 |
7.59 |
2.03 |
26.1 |
7.48 |
2.01 |
96.7 |
7.48 |
2.01 |
144 |
7.65 |
2.04 |
193 |
7.02 |
1.95 |
266 |
6.70 |
1.90 |
Stopped, due to stability after 120 h at 50 °C (criteria for performing the definitive test)
Hydrolysis Results for the Test Item at pH 9 and 20 °C
Hydrolysis Time [h] |
Concentration [g/L] |
Ln Concentration
|
0.00 |
7.65 |
2.03 |
26.1 |
7.47 |
2.01 |
96.8 |
7.80 |
2.05 |
145 |
8.13 |
2.09 |
193 |
7.70 |
2.04 |
266 |
7.63 |
2.03 |
314 |
7.67 |
2.04 |
Stopped, due to stability after 120 h at 50 °C (criteria for performing the definitive test)
Hydrolysis Results for the Test Item at pH 9 and 30 °C
Hydrolysis Time [h] |
Concentration [g/L] |
Ln Concentration
|
0.00 |
7.65 |
2.03 |
26.6 |
7.47 |
2.01 |
97.2 |
7.76 |
2.05 |
145 |
8.16 |
2.10 |
193 |
7.82 |
2.06 |
267 |
7.54 |
2.02 |
314 |
7.90 |
2.07 |
Stopped, due to stability after 120 h at 50 °C (criteria for performing the definitive test)
Hydrolysis Results for the Test Item at pH 9 and 50 °C
Hydrolysis Time [min] |
Concentration [g/L] |
Ln Concentration
|
0.00 |
7.65 |
2.03 |
26.9 |
7.80 |
2.05 |
97.6 |
7.86 |
2.06 |
146 |
8.09 |
2.09 |
194 |
7.68 |
2.04 |
267 |
7.49 |
2.01 |
315 |
7.49 |
2.01 |
Stopped, due to stability after 120 h at 50 °C (criteria for performing the definitive test)
Kinetics Considerations
At pH 7 and 9 the advanced test was stopped, due to stability at 50 °C after 120 h. Therefore no kinetics considerations were done at these pH values.
For pH 4 at all test conditions the ln concentration vs. time plots have regression graphs with slopes significantly non zero. First order reaction kinetics was applied for data computation. A confirmation of pseudo first order reaction kinetics with coefficients of determination > 0.8 was achieved for pH 4 and 50 °C. For pH 4 and 20 and 30 °C, no confirmation of pseudo first order reaction kinetics with coefficients of determination > 0.8 was achieved. Based on the obtained data the pseudo first order reaction kinetics was deemed to be the best fit model for computation of kinetics data.
Reaction Rate Constants and Half-Lives at pH 4
|
pH 4 |
||
|
20 °C |
30 °C |
50 °C |
Slope of regression graph |
-6.41 · 10-4 |
-7.86 · 10-4 |
-2.21 · 10-3 |
Correlation factor [r2] |
0.559 |
0.627 |
0.951 |
Reaction rate constant kobs [1/s] |
1.79 · 10-7 |
2.19 · 10-7 |
6.13 · 10-7 |
Half-life T½ [h] |
1077 |
880 |
314 |
Confidence interval of half-life T½ [h] |
738 to 2712 |
638 to 1735 |
276 to 353 |
Half-life T½ [d] |
44.9 |
36.7 |
13.1 |
Confidence interval of half-life T½ [d] |
30.8 to 113 |
26.6 to 72.3 |
11.5 to 14.7 |
Rounding differences may be possible, due to the usage of different software
Arrhenius Calculations
Results of Arrhenius Calculations
pH value |
[°C] |
-EA/R |
ln A |
EA [J * mol-1] |
4 |
20 |
-4033 |
-1.88 |
3.35 x 104 |
30 |
||||
50 |
Transformation Product
During LC-DAD analysis one (major) transformation product was observed on peak area basis at all temperatures. This transformation product (hereinafter labelled as T3) could not be mass-spectroscopically identified, as no chromatographic signals could be generated for the observed transformation products using LC-MS employing ESI+ ionisation.
At 50 °C three additional (minor) transformation products (hereinafter referred as T1, T2, T4) were observed during LC-DAD analysis. At 20 and 30 °C only the transformation product T2 was observed in addition to T3. These minor transformation products also could not be mass-spectroscopically identified, as no chromatographic signals could be generated for the observed transformation products using LC-MS employing ESI+ ionisation.
Based on the small retention time differences and the comparable UV-VIS spectra, it can be assumed, that all observed transformation products are structurally similar to the parent compound. On basis of the available information (non-ionizability, comparable UV-VIS spectra and small retention time differences) and the chemical sense, three transformation product structures were postulated. The postulated structures are probable candidates for the observed signals, but, due to their non-ionizability and the unavailability of reference materials, these structures could not be confirmed.
It could be assumed that all transformation products are present as copper complexes.
Formation of the Transformation Products T2 and T3 at pH 4 and 20 °C
Hydrolysis Time [h] |
[peak Area, mAU] |
|
T2 |
T3 |
|
0.00 |
- |
- |
24.3 |
180 |
- |
94.6 |
439 |
- |
143 |
416 |
- |
191 |
370 |
- |
264 |
282 |
- |
312 |
291 |
- |
361 |
336 |
- |
434 |
277 |
- |
504 |
- |
386 |
767 |
73 |
515 |
Formation of the Transformation Products T2 and T3 at pH 4 and 30 °C
Hydrolysis Time [h] |
[peak Area, mAU] |
|
T2 |
T3 |
|
0.00 |
- |
- |
24.7 |
225 |
- |
94.9 |
234 |
- |
143 |
498 |
- |
191 |
147 |
- |
265 |
94 |
- |
313 |
87 |
592 |
362 |
246 |
776 |
434 |
85 |
825 |
505 |
56 |
1168 |
767 |
- |
1716 |
Formation of the Transformation Products T1 to T4 at pH 4 and 50 °C
Hydrolysis Time [h] |
[peak Area, mAU] |
|||
T1 |
T2 |
T3 |
T4 |
|
0.00 |
- |
- |
- |
- |
25.3 |
- |
- |
668 |
- |
95.9 |
- |
523 |
2058 |
- |
144 |
-- |
462 |
2713 |
- |
192 |
- |
986 |
3330 |
- |
265 |
- |
1110 |
3777 |
- |
313 |
- |
1273 |
4134 |
- |
362 |
- |
1292 |
4177 |
- |
435 |
- |
1788 |
4366 |
- |
505 |
- |
2375 |
4530 |
- |
768 |
2072 |
963 |
4195 |
2111 |
Validity Criteria
Validity Criteria
Validity criterion |
Required |
This study |
First order kinetic |
To confirm first order behavior, the regression graph must have a correlation factor of ≥ 0.8. |
pH 4 |
Temperature |
The test temperature should be within ± 0.5 °C of the nominal temperature. |
pH 4 |
Test systems |
The pH values of the buffer solutions should be in the range of ± 0.1 pH at test temperature. |
Fulfilled |
Sensitivity |
Sensitivity of the analytical method should be sufficient to quantify test item concentrations at least down to a 90% reduction of the initial concentration. |
Fulfilled |
Description of key information
The test item showed a slow hydrolysis rate for pH 4 at 20 and 30 °C with a calculated half-life of 39.3 days at 25°C and a moderate hydrolysis rate for pH 4 at 50 °C.
At pH 7 and 9 no significant reduction of the test item concentration was observed at 50°C and therefore the test item was considered as hydrolytically stable under this condition and a half-life of > 1 year could be assumed for environmental typical temperatures.
Key value for chemical safety assessment
- Half-life for hydrolysis:
- 39.3 d
- at the temperature of:
- 25 °C
Additional information
Hydrolysis as a function of pH was determined according to OECD Guideline No. 111 and Council Regulation (EC) No. 440/2008, Method C.7. Analyses of the test item Reactive Blue 160 were performed via LC‑DAD on a reversed phase analytical column using the test item as external standard. The analytical method was validated with satisfactory results with regard to linearity, accuracy, precision and specificity.
The preliminary test was conducted with a test item concentration of 1.5 g/L in buffer solutions at pH 4, 7 and 9 at 50 °C. For all pH‑values the definitive test was performed, as a significant reduction (> 10%) of the test item concentration was observed in the preliminary test. The definitive test was conducted with a test item concentration of 7.5 g/L in buffer solutions at pH 4, 7 and 9 at temperatures of 20, 30 and 50 °C. Samples were taken at test start (0 h) and at 6 ‑ 10 spaced time points until test end. Pure test system (buffer solution at the respective pH‑value) was analyzed at test start and test end and there was no analytical interference with the test item. At pH 7 and 9 no significant reduction of the test item concentration was observed after 266 h at pH 7 and 315 h at pH 9 at 50 °C. Therefore, the definitive study at pH 7 and 9 was stopped and the test item was considered as hydrolytically stable under this condition.
Reaction rate constants, half-lives and activation energies were calculated from the analyzed samples at pH 4 based on a first order reaction kinetics model.
Reaction Rate Constants and Half-Lives at pH 4
| pH 4 | |||
| 20 °C | 30 °C | 50 °C | 25 °C 1) |
Reaction rate constant kobs [1/s] | 1.79 · 10-7 | 2.19 · 10-7 | 6.13 · 10-7 | 2.04· 10-7 |
Half-life T½ [h] | 1077 | 880 | 314 | 944 |
Half-life T½ [d] | 44.9 | 36.7 | 13.1 | 39.3 |
Number of data points | 11 | 11 | 11 | EA = 3.35 · 104 J * mol-1 |
Slope of regression graph | significantly non-zero |
|
1) = values calculated via Arrhenius equation
EA = activation energy
The test item showed a slow hydrolysis rate (> 30 d) for pH 4 at 20 and 30 °C and a moderate hydrolysis (2.4 h ≤ t1/2 ≤ 30 d) for pH 4 at 50 °C.
At pH 7 and 9, the test item was considered as hydrolytically stable under this condition and a half-life of > 1 year could be assumed for environmental typical temperatures.
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