2,2,3,3,4,4,5,5,6,6-decafluoro-6-trifluorovinyloxyhexanenitrile

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February 12, 2020 to March 25, 2020

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

yes

Remarks:

1) Only one temperature was investigated. 2) pH at each time point was measured using pH strips. 3) Aqueous media was not purged of oxygen. 4) it is unknown if MV5CN is dosed at less than half of the saturated water solubility concentration.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

2,2,3,3,4,4,5,5,6,6-decafluoro-6-trifluorovinyloxyhexanenitrile

EC Number:

443-050-2

EC Name:

2,2,3,3,4,4,5,5,6,6-decafluoro-6-trifluorovinyloxyhexanenitrile

Cas Number:

120903-40-4

Molecular formula:

C8F13NO

IUPAC Name:

2,2,3,3,4,4,5,5,6,6-decafluoro-6-[(1,2,2-trifluoroethenyl)oxy]hexanenitrile

Specific details on test material used for the study:

Two test materials were used for the study:
Parent compound: MV5CN:
Source and lot/batch No.of test material :MV-5CN-ANL1900560
- Purity: 99.45%
- Expiration date of the lot/batch: 09-09-2024

Hydrolysis product: MV5CN amide (MTDID 59038)
Source and lot/batch No.of test material : US274203-03-004
- Purity: 95.9%
- Expiration date of the lot/batch:12-08-2024

Radiolabelling:

no

Study design

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products: For pH 4, 7, 9 buffer, 13 sampling points were prepared, 12 sampling points were analyzed for pH 4 and pH 7, 10 sampling points were analyzed for pH 9. For algae medium, 7 sampling points were prepared and analyzed. For fresh MilliQ reagent water, 13 sampling points were prepared and 10 sampling points were analyzed. For MilliQ reagent water aged one week, 7 sampling points were prepared and analyzed.
- Sampling method: Aliquots were prepared by inserting a disposable syringe/needle assembly through the vial’s septum and withdrawing the desired volume. The removed sample aliquot was then injected through the bonded septum-seal of a separate 40-mL VOA vial containing MilliQ reagent water. The total volume (MilliQ + sample aliquot) in the analysis vial was always 10 mL. At a minimum, at least one dosed vial per test system had at least two replicate aliquots prepared.
- Sampling methods for the volatile compounds, if any: None
- Sampling intervals/times for pH measurements: Prior dosing, the pH of the buffer system was confirmed using pH test strips. After dosing and after aliquot preparation, the pH of the dosed system was verified using pH test strips.
- Sampling intervals/times for sterility check: None. Prior to dosing with test substance, the purchased buffers and the algal media were sterilized via filtration through a presterilized Thermo Scientific™ Nalgene™ Rapid-Flow™ 75mm filter unit. MilliQ reagent water was used as dispensed from the laboratory’s filtration system (no sterilization filtration performed).
- Sample storage conditions before analysis: No storage. Samples were held on the autosampler until injection. It is presumed that the analyte partitioned immediately to the headspace of the receiving vial after the aliquot was transferred.

Buffers:

- pH: 4, 7, 9 buffer
Type of pH buffer:
pH 4: Potassium Hydrogen Phthalate Buffer (KHP)
pH 7: Potassium Phosphate (Monobasic) Buffer (KH2PO4)
pH 9: Boric Acid Buffer (H3BO3)

Buffer solutions at pH 4, 7, and 9 were purchased certified buffers solutions.

Additional test system including MilliQ water (pH 4.5) and OECD M2 Algal media (pH 7 - 7.5).
MilliQ reagent water was used as dispensed from the laboratory’s filtration system (no sterilization filtration performed).
Algal media was prepared at an external laboratory in accordance with OECD guidelines.

Details on test conditions:

The stability of MV5CN in various aqueous media types at ambient temperature was investigated in this study. A Tier I preliminary test at 50°C for five days was not performed.
Test systems include pH 4, 7, 9 buffer solutions, OECD Algal media (pH 7 -7.5), and MilliQ reagent water (pH 4.5). Test vials were 20-mL VOA vials with 24-mm bonded septa caps.

Test vials were filled to near zero-headspace with the appropriate aqueous test system and sealed with the bonded septum-seal caps. Five µL of the testing spiking solution was added to each non-method blank vial. After spiking, the test system vials were inverted three times and placed in an incubator/shaker set to 100 rpm at ambient conditions. Vial 1 for each test system was not placed on the incubator as aliquots were prepared for analysis immediately after spiking, typically within 5 minutes or less after the spike was delivered. Aliquots were prepared by inserting a disposable syringe through the vial’s septum and withdrawing the desired volume. The removed sample aliquot was then injected through the bonded septum-seal of a separate 40-mL VOA vial containing MilliQ reagent water. The volume of MilliQ reagent water in the analysis vial varied depending on the volume of the sample aliquot added. The total volume (Milli Q + sample aliquot) in the analysis vial was always 10 mL. After aliquot preparation, the pH of the dosed system was verified using pH test strips. Addition of the MV5CN did not change the pH of the test system within ±0.5 pH units.

Given the volatile nature of the test substance, it was presumed that the test substance would rapidly transfer into the available headspace of analysis vial and thus stop aqueous hydrolysis or other chemical transformation processes. Therefore, the elapsed time represents the time between dosing the vials and aliquoting samples for analysis. It excludes the time the prepared analysis aliquots sat on the instrument autosampler awaiting analysis. Upon analysis of the data, the elapsed time was adjusted for the analytical delay for comparative purposes.

Duration of test

Duration of test 1

Duration:

24 h

pH:

4

Temp.:

23 °C

Initial conc. measured:

254 µg/L

Remarks:

Ambient temperature. For pH 4 buffer. Dosed at 217 ng/mL MV5CN, initial (elapsed time ~ 6 min) measured conc. was 254 ng/mL (RPD% = 38%) for MV5CN and 15.7 ng/mL (RPD% =1.3%) for MV5CN amide.

Duration of test 2

Duration:

5 h

pH:

7

Temp.:

23 °C

Initial conc. measured:

113 µg/L

Remarks:

Ambient temperature. For pH 7 buffer. Dosed concentration of 788 ng/mL MV5CN, initial (elapsed time ~ 2 min) measured conc. was 113 ng/mL (RPD% = 22%) for MV5CN and 681 ng/mL (RPD% = 25%) for MV5CN amide.

Duration of test 3

Duration:

1 h

pH:

9

Temp.:

23 °C

Initial conc. measured:

23.6 µg/L

Remarks:

Ambient temperature. For pH 9 buffer. Dosed concentration of 788 ng/mL MV5CN, initial (elapsed time ~ 1 min) measured conc. for MV5CN was 23.6 ng/mL (RPD% = 87%) for MV5CN and 672 ng/mL (RPD% = 12%) for MV5CN amide.

Duration of test 4

Duration:

4 h

pH:

4.5

Temp.:

23 °C

Initial conc. measured:

45.3 µg/L

Remarks:

Ambient temperature, for Freshly Dispensed Milli-Q Reagent Water. Dosed concentration of 206 ng/mL MV5CN, initial (elapsed time ~ 6 min) measured conc. for MV5CN was 45.3 ng/mL (RSD% =18%) for MV5CN and 171 ng/mL (RSD% =7.5%) for MV5CN amide.

Duration of test 5

Duration:

1.5 h

pH:

7

Temp.:

23 °C

Initial conc. measured:

58.7 µg/L

Remarks:

Ambient temperature, for OECD Algal media (pH 7-7.5). Dosed concentration of 788 ng/mL MV5CN, initial (time 0) measured conc. was 58.7 ng/mL (RPD% =22%) for MV5CN and 700 ng/mL (RPD% =20%) for MV5CN amide.

Number of replicates:

At a minimum, at least one dosed vial per test system had at least two replicate aliquots prepared. A single replicate from a reaction vessel/sampling point was prepared for the rest of the dosed vials.

Statistical methods:

For pH 4 and pH 7, the rate constant, k, and half-life, t1/2, were determined by plotting the natural logarithmic transform of the measured MV5CN concentration as a function of elapsed time and performing linear regression, assuming that the loss of MV5CN followed pseudo first-order reaction kinetics.
The slope of the resulting linear regression provided the rate constant k in units of hours^-1 or min^-1. The resulting half-life was calculated using the following equation:
DT50 = ln(2)/k

Where:
DT50:hydrolysis half-lives (hours or minutes);
k:hydrolysis rate coefficient (hours^-1 or min^-1)

For pH 9, MilliQ water and OECD algal media, the observed loss of MV5CN was too fast to calculate a half-life using the approach described above, an estimated maximum half-life is provided.

Results and discussion

Transformation products:

yes

Identity of transformation products

No.:

#1

Reference

Reference substance name:

Unnamed

IUPAC name:

2,2,3,3,4,4,5,5,6,6-decafluoro-6-[(trifluoroethenyl)oxy]hexanamide

Molecular formula:

CF2=CF-O-C5F10CONH2

Molecular weight:

391

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

- Formation and decline of each transformation product during test: Hydrolytic degradation of MV5CN to the corresponding MV5CN amide
- Pathways for transformation: See Fig 1

Dissipation DT50 of parent compound

Dissipation DT50 of parent compound 1

Key result

pH:

4

Temp.:

23 °C

Hydrolysis rate constant:

0.18 h-1

DT50:

3.85 h

Type:

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

Remarks on result:

other: At ambient temperature. 95% confidence interval for DT50: 3.44 -4.375 hours. Elapsed time represents the time between dosing the sample vial and pulling an aliquot. The sample analysis delay is not included.

Dissipation DT50 of parent compound 2

Key result

pH:

7

Temp.:

23 °C

Hydrolysis rate constant:

0.009 min-1

DT50:

1.32 h

Type:

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

Remarks on result:

other: At ambient temperature. 95% confidence interval for DT50: 1.16 -1.50 hours. Adjusted elapsed time represents the time between dosing the sample vial and the start of the GC/MS analysis. The sample analysis delay is included.

Dissipation DT50 of parent compound 3

pH:

9

Temp.:

23 °C

DT50:

< 0.3 h

Type:

other: estimated maximum half life.

Remarks on result:

other: At ambient temperature. Observed loss of MV5CN was too fast to measure a half-life. Provided value is a conservative estimated maximum half-life.

Dissipation DT50 of parent compound 4

pH:

4.5

Temp.:

23 °C

DT50:

< 2 h

Type:

other: Estimated maximum half-life.

Remarks on result:

other: At ambient temperature. For MilliQ water (pH 4.5). Observed loss of MV5CN was too fast to measure a half-life. Provided value is a conservative estimated maximum half-life.

Dissipation DT50 of parent compound 5

pH:

7

Temp.:

23 °C

DT50:

< 0.2 h

Type:

other: estimated half life

Remarks on result:

other: At ambient temperature. For algal media (pH 7 -7.5). Observed loss of MV5CN was too fast to measure a half-life. Provided value is a conservative estimated maximum half-life.

Details on results:

Measured concentration of MV5CN and MV5CN amide and mass balance at time 0 and end time were summarized in Table 1.
Hydrolysis half-lives are presented in Table 2.

The elapsed time represents the time between dosing the sample vial and aliquoting for analysis, while the adjusted elapsed time represents the time between dosing the sample vial and the start of the GC/MS analysis.

Mass balance for each time point was evaluated by converting the measured concentrations of MV5CN and MV5CN amide concentration in ng/mL to nmol amounts and comparing to the nmol of MV5CN dosed.

For pH 4, mass balance of 100±50% for MV5CN and MV5CN amide was observed for samples aliquoted between 6 minutes and 280 minutes after initial dosing of the test system with MV5CN (elapsed time = t~0 to t=4.7 hours). Aliquots prepared between 14 hours and 24 hours after dosing exhibited much lower mass balance (4.48%-16%) suggesting that the MV5CN could be transforming to something other than the corresponding amide. The half-life is estimated to be 3.85 hours (95% confidence interval of 3.44 to 4.38 hours) based on elapsed time of ~6 minutes to ~24 hours, while calculated half-life was 3.73 hours based on adjusted elapsed time. The half-life of 3.73 hours is within the 95% confidence interval of the unadjusted plot.

For pH 7, mass balance of 100±15% for MV5CN and MV5CN amide was observed for all analyzed time points (elapsed time between t~0 to t=318 minutes). The half-life is estimated to be 41 minutes (95% confidence interval of 37 to 46 minutes) based on elapsed time of 5 minutes to 240 minutes, while calculated half-life was 79 minutes (95% confidence interval of 70 to 90 minutes) based on adjusted elapsed time.

For pH 9, mass balance of 100±25% for MV5CN and MV5CN amide was observed when sample aliquots were analyzed within four hours of aliquot preparation (adjusted elapsed time ≤ 234 minutes) with one exception of a calculated mass balance of 42.5% for sample with adjusted elapsed time of 144 minutes. At pH 9, the conversion of MV5CN to MV5CN amide is quite fast, almost 97% loss of the MV5CN theoretical dose concentration was observed for samples with elapsed time between 1 minutes and 2 minutes (adjusted elapsed time of 21- 83 minutes). All subsequent samples with elapsed time between 10 minutes and 60 minutes ( adjusted elapsed time of 42- 234 minutes) had no quantifiable levels of MV5CN upon analysis. Pseudo-first order kinetics plots were not prepared for pH9. The half-life has been estimated as < 20 minutes (0.3 hours). This value was based on a sample with adjusted elapsed time of 21 minutes and the MV5CN concentration was significantly less than half the theoretical dosing concentration.

For MilliQ Reagent Water, there was significant delay between aliquoting the time points (~ 6 minutes to ~4 hours) and analysis by purge and trap GC/MS (~ 132 minutes to 689 minutes). Mass balance of 100±10% for MV5CN and MV5CN amide was observed for the first vial replicates aliquoted immediately after dosing (aliquoted ~6 minutes, analyzed ~ 132 minutes). All other time points exhibited mass balance between approximately 22% to 62%. No attempt was made to calculate a half-life. A maximum estimated half-life of <2 hours was arbitrarily assigned based on the first vial results where the concentration of MV5CN was 22% of the theoretical dosed concentration (45.3 ng/mL average concentration versus a theoretical dose of 206 ng/mL).

Aged MilliQ water: Additional Milli Q reagent water samples were prepared using “aged” Milli Q water. The “aged” water was dispensed and stored in a Nalgene container at ambient conditions for approximately one week before dosing with MV5CN. The vials prepared were aliquoted within an hour (approximately) of dosing and analyzed within 8 hours. Mass balance of 100±12% was observed for all vials which was a significant difference from the fresh MilliQ water. This observation suggests that the presence of dissolved oxygen in the water may contribute to the fate of MV5CN and associated degradation products. No attempt was made to calculate a half-life. Stability of the MV5CN amide in aged Milli Q was not measured.

For OECD Algal Media, six time points were initially prepared between t~0 and t~95 minutes elapsed time. Mass balance of 100±20% was observed for these time points. Observed conversion of MV5CN to MV5CN amide was quick and no MV5CN was measured for elapsed time after 30 minutes. Effort was made to minimize the elapsed time between aliquoting and analysis. A pseudo-first order plot was generated for the first five time points (elapsed time t~0 to t~30 minutes) and a reasonably linear relationship was observed. Using the slope, the half-life was calculated to be approximately 5 minutes. However, it should be emphasized that the first measured concentrations for the aliquots prepared immediately after dosing indicated that 92% of the theoretical dose was gone. Given that the samples purge for 11 minutes before desorption to the GC/MS, the half-life was arbitrarily stated as < 0.2 hours (12 minutes).

Stability of MV5CN amide: the stability of the MV5CN amide over a minimum of 72 hours was investigated. Results of the amide stability are presented in Table 3. Recoveries ranged from 73.1% to 116% with the exception of pH 9 over 72 hours where significant loss of the MV5CN amide was observed (loss of ~73% of the starting concentration).

Any other information on results incl. tables

Table 1. Summary of measured concentration of MV5CN and MV5CN amide ⁽¹⁾

pH	Exp. endpoints (hours)  ^(2)	Sampling Time points^(3)	MV5CN Dosed Conc. (ng/mL)	MV5CN Conc. at TP 0 (ng/mL)	MV5CN Conc. at end TP (ng/mL)	MV5CN amide Conc. at TP 0 (ng/mL)	MV5CN amide Conc. at end TP (ng/mL)	Mass balance at TP 0 (%)	Mass balance at end TP (%)
4	24	12	217	254 (38%)	3.47 (10%)	15.7 (1.3%)	11.3 (7.3%)	124 (25%)	6.58 (5.6%)
7	4	11	788	113 (22%)	< 3.10	681 (25%)	813 (7.8%)	96.6 (12%)	98.3 (5.3%)
9	1	10	788	23.6 (87%)	< 3.10	672 (12%)	718 (13%)	84.4 (11%)	87.0 (8.9%)
MilliQ water (pH 4.5)	2	6	206	45.3 (RSD = 18%) ^(4)	< 0.62	171 (RSD = 7.5%) ^(4)	89.6 (2.6%)	101 (RSD = 8.3%) ^(4)	41.4 (1.9%)
Algal media (pH 7 -7.5)	0.5	5	788	58.7 (22%)	<1.46	700  (20%)	732 (9.3%)	92.2 (12%)	88.6 (6.5%)

(1)  Unless otherwise noted, the concentration are the average concentration of duplicated samples aliquoted from the same vial at the same time. Number in paratheses are the %RPD of the duplicated samples.

(2)  The exp. endpoint is defined as the last time point collected and analyzed or the elapsed time when measured MV5CN concentrations were first determined to be less than the lower limit of quantitation.

(3)  Sampling time points include the last time point aliquoted, or when measured MV5CN concentrations were first determined to be less than the lower limit of quantitation.

(4)  Triplicate samples

Table 2. Summary of MV5CN Stability in Aqueous Media

Test System	Half-Life (hours)	95% Confidence Limits Half-Life (hours)	Exp. Endpoint (hours) (a)	% MV5CN lost at Exp. Endpoint	Mass Balance to the Amide Observed
pH 4	3.85	3.44-4.375	24	98.40%	No
pH 7	1.32	1.16-1.50	4	>99.6%	Yes
pH 9	<0.3 (b)	NA	1 (c)	>99.8%	Yes
MilliQ (pH=4.5)	<2 (b)	NA	2	>99.7%	No
M2 algal media (pH=7-7.5)	<0.2 (b)	NA	0.5	>99.8%	Yes

(a) Experimental end point is defined as the last time point collected and analyzed – or the elapsed time when measured MV-5CN concentrations were first determined to be less than the lower limit of quantitation.
(b) Observed loss of MV-5CN was too fast to measure a half-life. Provided value is a conservative estimated maximum.
(c) The experimental endpoint listed was adjusted for delay between aliquoting and analysis.

Table 3. Stability of the MV5CN Amide*

Test System	Time Frame	%Recovery of the MV5CN Amide
pH 4	t~9 Days	83.4% (RSD: 3.7%, N=3)
pH 7	t~0	92.3% (RSD: 4.4%, N=3)
pH 7	t~24 hours	104% (RSD: 4.1%, N=3)
pH 7	t~96 hours	109% (RSD: 5.4%, N=3)
pH 9	t~0	91.3% (RSD: 5.3%, N=3)
pH 9	t~72 hours	22.9% (RSD: 2.9%, N=3)
MilliQ	t~0	108% (RPD: 4.0%, N=2)
MilliQ	t~24 hours	98.7% (RSD: 2.2%, N=3)
MilliQ	t~72 hours	74.8% (RSD: 12%, N=3)
M2 algal media	t~0	116% (RSD: 4.5%, N=3)
M2 algal media	t~48 hours	94.9% (RSD: 5.2%, N=3)
M2 algal media	t~120 hours	73.1% (RSD: 13%, N=3)

*The samples were spiked with 1210 ng/mL of MV5CN amide with the exception of pH 4 samples which were spiked with 81.5 ng/mL MV5CN amide.

Applicant's summary and conclusion

Conclusions:

MV5CN is unstable in various aqueous media, with half-lives range from < 0.2 hours for OECD algal media to 3.85 hours for pH 4 buffer.

Executive summary:

MV5CN stability in aqueous media (pH 4, 7, and 9 buffer, MillQ water, and OECD algal media) were conducted at ambient temperature based largely on the OECD 111 “Hydrolysis as a Function of pH” guideline.

Test vials were filled to near zero-headspace with the appropriate aqueous test system and sealed with the bonded septum-seal caps. MV5CN spiking solution was added to each non-method blank vial. After dosing, the test system vials were inverted three times and placed in an incubator/shaker set to 100 rpm at ambient conditions. Vial 1 for each test system was not placed on the incubator as aliquots were prepared for analysis typically within 5 minutes or less after dosing. The remaining test vials were incubated at ambient temperature until aliquot for analysis. For pH 4, 7, 9 buffer and MilliQ water, 13 sampling points were prepared and at least 10 sampling points were analyzed. For algae medium, 7 sampling points were prepared and analyzed. MV5CN and MV5CN amide concentrations in aqueous media were measured using purge and trap gas chromatography/mass spectrometry (PT-GC/MS).

For pH 4 and pH 7 test system, the hydrolytic rate constant, k, and hydrolytic halflife,t1/2, for MV5CN were determined by plotting the natural logarithmic transform of the measured MV5CN concentration as a function of elapsed time, and performing linear regression, assuming that the hydrolysis followed pseudo first-order reaction kinetics. A minimum of eight time-points with quantifiable results were obtained and included in the pseudo first-order kinetics regression plot.  For pH 9, MilliQ water and OECD algal media, the observed loss of MV5CN was too fast to calculate a half-life using the approach described above, an estimated maximum half-life is provided.

Under the condition of the test, MV5CN hydrolyzed rapidly with hydrolysis half-lives ranged from < 0.2 hours for OECD algal media  to 3.85 hours for pH 4 buffer.

Additionally, the stability of the MV5CN amide over a minimum of 72 hours was investigated. Recoveries ranged from 73.1% to 116% with the exception of pH 9 over 72 hours where significant loss of the MV5CN amide was observed (loss of ~73% of the starting concentration).

Mass balance for each time point was evaluated by converting the measured concentrations of MV5CN and MV5CN amide concentration in ng/mL to nmol amounts and comparing to the nmol of MV5CN dosed. Mass balance at end time point ranged from 6.58% (pH 4) to 98.3% (pH 7). Mass balance to amide were observed for pH 7, 9 and Algal media, but not observed for pH 4 and MilliQ water. For pH 4, mass balance of 100±50% was observed for samples aliquoted ≤ 280 minutes after initial dosing, aliquots prepared between 14 hours and 24 hours after dosing exhibited much lower mass balance (4.48%-16%) suggesting that the MV5CN could be transforming to something other than the corresponding amide. For MilliQ water, mass balance of 100±10% was observed for the first vial replicates aliquoted immediately after dosing (aliquoted ~6 minutes, analyzed ~ 132 minutes). All other time points exhibited mass balance between approximately 22% to 62%. Additional Milli Q reagent water samples were prepared using MilliQ water aged one week and were aliquoted within an hour (approximately) of dosing and analyzed within 8 hours. Mass balance of 100±12% was observed for all vials which was a significant difference from the fresh MilliQ water. This observation suggests that the presence of dissolved oxygen in the water may contribute to the fate of MV5CN and associated degradation products.

This is a study similar to guideline and not conducted under GLP. There were some deviations from guideline: 1) Only one temperature was investigated. 2) pH at each time point was measured using pH strips. 3) Aqueous media was not purged of oxygen. 4) it is unknown if MV5CN is dosed at less than half of the saturated water solubility concentration. Therefore, this study is considered reliable with restriction. For all aqueous media, the observed half-life of MV5CN was significantly less than 12 hours meeting the ECHA guidance for waiving water solubility study.