Pyrasulfotole

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27 Jan 2003 - 22 Mar 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA Guideline Subdivision N 161-1 (Hydrolysis)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Canada PMRA DACO Number 8.2.3.2

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products: Sampling intervals for all three pH values at 0, 2, 7, 14, 22 and 30 days post-treatment.
- Sampling methods for the volatile compounds, if any: Volatile traps were not used (based on results in the preliminary study)
- Sampling intervals/times for pH measurements: The pH and sterility were measured at each sampling interval.
- Sampling intervals/times for sterility check: Sterility was measured by applying 1 mL of the test solution from each sample at each interval to 3M PetrifilmTM aerobic count plates. The plates were then incubated at 37 °C for 48 to 72 h. The initial study was restarted because the water bath temperature probe failed.
- Sample storage conditions before analysis: Samples were typically analyzed the day of sampling with the maximum storage duration before analysis being 3 d. The samples were stored under refrigerated conditions before analysis if analysis was not conducted on the sampling date. No storage stability data was generated because samples were analyzed within 30 days of collection.

Buffers:

Buffer solutions were made with Milli-Q water as follows:
- pH: 5
- Composition of buffer: Acetate 0.01 M. Acetic acid (0.01M in water) was added to 500 mL of 0.01 M sodium acetate until pH 5 was obtained.

- pH: 7
- Composition of buffer: Tris(hydroxymethyl)aminomethane, 0.01 M. Approximately 50 mL of 0.1M HCl to obtain pH 7.

- pH: 7
- Composition of buffer: Borate approx. 0.009 M. Approximately 40 mL of 0.1M NaOH was added to 500 mL of 0.01 M Boric acid to obtain pH 9.

The acetate, tris, and borate buffers were used since they are unlikely to affect the rate of hydrolysis at their respective pH.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: 30 mL amber glass serum vial equipped with a Teflon lined septum and crimp cap were used. The test systems were maintained in a covered waterbath. The temperature was held at 25 ± 1 °C.
- Sterilisation method: The test systems were autoclaved for 60 minutes at >200 °F (14 lbs/in2) to sterilize the system.
- Lighting: complete darkness
- Measures taken to avoid photolytic effects: The test systems were maintained in the dark.
- Details on test procedure for unstable compounds: test substance is stable
- Details of traps for volatile, if any: not performed
- If no traps were used, is the test system: closed
- Is there any indication of the test material adsorbing to the walls of the test apparatus? Adsorption of the test compound to the test vessels was not indicated based on the material balances.

TEST MEDIUM
- Volume used/treatment: 20 mL
- Kind and purity of water: MilliQ water

OTHER TEST CONDITIONS
- Adjustment of pH: no

Duration:

30 d

pH:

5

Temp.:

24.9 °C

Initial conc. measured:

0.14 mg/L

Duration:

30 d

pH:

7

Temp.:

24.9 °C

Initial conc. measured:

0.14 mg/L

Duration:

30 d

pH:

9

Temp.:

24.9 °C

Initial conc. measured:

0.14 mg/L

Number of replicates:

Two at each interval

Positive controls:

yes

Remarks:

Pond water from Stilwell, KS (Bayer Research Park) was used as a positive control to demonstrate a non-sterile reading from a 3M Petrifilm aerobic count plate.

Negative controls:

no

Statistical methods:

Sample standard deviations and mean were calculated.

Preliminary study:

Preliminary work was conducted at 50 °C with pH values 4, 7, and 9 for 5 days. Four test systems were set up for each pH for a total of twelve. The buffers used were acetate, tris, and borate with approximate concentrations of 0.01 M. It was conducted to identify if any volatiles are formed. This was not the case.

Transformation products:

no

Remarks:

No transformation products were formed, and therefore identification was not performed.

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

The test item did not degrade significantly in pH 5, 7, and 9 buffer solutions. No major transformation products were formed in this study. Minor degradates did not exceed 3.3% of the applied radioactivity.

pH:

5

Temp.:

24.9 °C

Duration:

30 d

Remarks on result:

other:

Remarks:

Mean material balance of applied radioactivity after 30 days: 100.4%

pH:

7

Temp.:

24.9 °C

Duration:

30 d

Remarks on result:

other:

Remarks:

Mean material balance of applied radioactivity after 30 days: 99.9%

pH:

9

Temp.:

24.9 °C

Duration:

30 d

Remarks on result:

other:

Remarks:

Mean material balance of applied radioactivity after 30 days: 100.3%

pH:

5

Temp.:

24.9 °C

Remarks on result:

not measured/tested

Remarks:

Due to the minimal degradation of the test item in all three buffers, degradation kinetics were not determined.

pH:

7

Temp.:

24.9 °C

Remarks on result:

not measured/tested

Remarks:

Due to the minimal degradation of the test item in all three buffers, degradation kinetics were not determined.

pH:

9

Temp.:

24.9 °C

Remarks on result:

not measured/tested

Remarks:

Due to the minimal degradation of the test item in all three buffers, degradation kinetics were not determined.

Other kinetic parameters:

Due to the minimal degradation of the test item in all three buffers, degradation kinetics were not determined.

Details on results:

TEST CONDITIONS
- pH, sterility, temperature, and other experimental conditions maintained throughout the study: Yes

MAJOR TRANSFORMATION PRODUCTS
- No transforamtion products were identified.

MINOR TRANSFORMATION PRODUCTS
- No transforamtion products were identified.

Results with reference substance:

Reference substance were not utilized because there were not significant degradation of the parent compound.

Transformation of test item expressed as percentage of applied radioactivity (mean ± S.D.), in pH 5 buffer solution

	Sampling Times [days]
	0	2	7	14	22	30
test item	99.4 ± 0.6	99.4 ± 0.6	98.7 ± 0.1	98.4 ± 1.7	100.1 ± 0.3	100.4 ± 0.0
Unknown A	0.0 ± 0.0	0.0 ± 0.0	1.3 ± 0.3	1.3 ± 0.3	0.0 ± 0.0	0.0 ± 0.0
Unknown B	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
Unknown C	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
Total Extractable Residues	99.4 ± 0.6	99.7 ± 0.0	100.0 ± 0.1	99.3 ± 0.4	100.1 ± 0.3	100.4 ± 0.0
CO2	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0
Volatile Organic	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0
Total Volatile Organic	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0
Bound to Apparatus Walls	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0
Total % Recovery	99.4 ± 0.6	99.4 ± 0.6	99.4 ± 0.6	99.4 ± 0.6	99.4 ± 0.6	99.4 ± 0.6

  

Transformation of test item, expressed as percentage of applied radioactivity (mean ± S.D.), in pH 7 buffer solution

	Sampling Times [days]
	0	2	7	14	22	30
test item	100.2 ± 0.6	100.2 ± 0.6	100.3 ± 0.5	100.0 ± 0.4	98.8 ± 2.4	99.9 ± 0.7
Unknown A	0.0 ± 0.0	1.3 ± 1.8	0.0 ± 0.0	0.0 ± 0.0	1.5 ± 2.1	0.0 ± 0.0
Unknown B	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
Unknown C	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
Total Extractable Residues	100.2 ± 0.6	99.9 ± 0.3	100.3 ± 0.5	100.0 ± 0.4	100.3 ± 0.3	99.9 ± 0.7
CO2	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0
Volatile Organic	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0
Total Volatile Organic	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0
Bound to Apparatus Walls	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0
Total % Recovery	100.2 ± 0.6	99.9 ± 0.3	100.3 ± 0.5	100.0 ± 0.4	100.3 ± 0.3	99.9 ± 0.7

  

Transformation of test item expressed as percentage of applied radioactivity (mean ± S.D.), in pH 9 buffer solution

	Sampling Times [days]
	0	2	7	14	22	30
test item	97.6 ± 0.4	98.1 ± 0.3	96.6 ± 0.4	97.5 ± 0.2	96.9 ± 1.8	95.7 ± 0.1
Unknown A	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.9 ± 1.2	0.0 ± 0.0
Unknown B	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
Unknown C	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0	0.0 ± 0.0
Total Extractable Residues	100.4 ± 0.1	100.5 ± 0.0	100.0 ± 0.2	100.1 ± 0.3	100.4 ± 0.4	100.3 ± 0.1
CO2	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0
Volatile Organic	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0
Total Volatile Organic	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0
Bound to Apparatus Walls	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0	n/a ± 0.0
Total % Recovery	100.4 ± 0.1	100.5 ± 0.0	100.0 ± 0.2	100.1 ± 0.3	100.4 ± 0.4	100.3 ± 0.1

 

 

Validity criteria fulfilled:

not applicable

Description of key information

The DT50 values for the degradation of test item were not calculated for pH 5, pH 7 and pH 9 because of limited degradation.

Additional information

One experimental study is available investigating the hydrolysis of the test item according to EPA Guideline N 161-1 (M-060005-01-1). Hydrolysis of the test item at 0.14 mg/L was studied in the dark at 24.9 °C (±0.02 °C) in sterile aqueous buffers at pH 5 (0.01 M sodium acetate), pH 7 (0.01 M tris [(HOCH2)3CNH2]), and pH 9 (0.01 M sodium borate) for 30 d. A preliminary study at 50 °C demonstrated that no volatiles were formed during hydrolysis. Therefore, test vessels were not connected to traps for the collection of CO2 and organic volatiles. Duplicate samples were analyzed at 0, 2, 7, 14, 22, and 30 d. The samples were analyzed directly by HPLC without extraction. The average material balance was 99.8 %, (range = 99.0 to 100.5 %), 100.1 %, (range = 99.3 to 100.6 %), and 100.3 %, (range = 99.8 to 100.7 %) of the applied radioactivity at pH 5, pH 7, and pH 9, respectively. Most of the applied radioactivity was associated with the parent compound at test termination in the pH 5, 7 and 9 buffer solutions. A minor transformation product, unknown A, was formed at a maximum of 1.8 % (day 14; pH 5), 3.0 % (day 22, pH 7), and 1.8 % (day 22, pH 9) of the applied radioactivity. Unknown A was not consistently observed in the study. Another minor transformation product, unknown B, was formed at a maximum of 3.4 % (day 7 and 30; pH 9) of the applied radioactivity. Unknown B remained relatively constant throughout the study. A third minor transformation product, unknown C, was formed at a maximum of 1.5 % (day 30, pH 9) of applied radioactivity. Unknown C was only observed in the day 30 interval of the pH 9 samples. The mean unidentified radioactivity was <1 %, <1 %, and 4.6 % of the applied radioactivity at pH 5, pH 7, and pH 9, respectively (at day 30). The DT50 values for the degradation of test item were not calculated for pH5, pH 7 and pH 9 because of limited degradation.