2-hydroxy-4-(trifluoromethyl)benzoic acid

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From March 27th, 2019 to May 29th, 2019

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:

EPA OPPTS 835.2130 (Hydrolysis as a Function of pH and Temperature)

Version / remarks:

1998

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals for the parent/transformation products: at the start and at the end of the study (days 0 and 5).
- Sampling method: a duplicate sample of each pH was taken immediately after the addition of the test item on Day 0 and after day 5 of incubation.
- Sampling intervals/times for pH measurements: at the start and at the end of the study (days 0 and 5).
- Sampling intervals/times for sterility check: at the start and at the end of the study (days 0 and 5).
- Sample storage conditions before analysis: none, samples were analysed immediately after sampling.
- Other observation, if any (e.g.: precipitation, color change etc.): no.

Buffers:

- pH: 4.0, 7.0, 9.0.
- Preparation of buffer solutions: Buffer Solution of pH 4.0: An aliquot of 410 mL of 0.2 M acetic acid solution and 90 mL of 0.2 M anhydrous sodium acetate solution were transferred into a 2000 mL volumetric flask and the volume was made up to the mark using Milli-Q water. The pH of the resulting buffer solution measured was found to be 4.1. The pH was adjusted to 4.00 by using 1.0 mL of 0.1% acetic acid solution. The final pH of the resulting buffer solution measured was found to be 4.00. Buffer Solution of pH 7.0: An aliquot of 195 mL of 0.2 M monobasic sodium phosphate solution and 305 mL of 0.2 M dibasic sodium phosphate solution was transferred into a 2000 mL volumetric flask and the volume was made up to the mark using Milli-Q water. The pH of the resulting buffer solution measured was found to be 6.9. The pH was adjusted to 7.00 by using 0.6 mL of 0.1 N sodium hydroxide solution. The final pH of the resulting buffer solution measured was found to be 7.00. Buffer Solution of pH 9.0: An aliquot of 1000 mL of 0.1 M boric acid solution was transferred into a 2000 mL volumetric flask and the volume was made up to the mark using Milli-Q water. The pH of the resulting solution measured was found to be 8.8. The pH was adjusted to 9.00 by using 1.0 mL of 50% w/v NaOH solution. The final pH of the resulting buffer solution measured was found to be 9.00.

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: 200 mL volumetric flask glassware.
- Sterilisation method: filtration
- Lighting: no
- Measures taken to avoid photolytic effects: the test was carried out in darkness
- Measures to exclude oxygen: samples were sonicated for about 5 min
- Is there any indication of the test material adsorbing to the walls of the test apparatus? no

TEST MEDIUM
- Kind and purity of water: Milli-Q water
- Preparation of test medium: The prepared buffer solutions were sterilized by passing through a 0.2 µm sterilized filter and oxygen in the solutions was removed by sonication for about 5 minutes.
- Identity and concentration of co-solvent: acetonitrile, less than 1% of the final volume

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

17.31 mg/L

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

17.47 mg/L

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

17.47 mg/L

Number of replicates:

2

Positive controls:

no

Negative controls:

yes

Preliminary study:

The preliminary tests were performed in a dark incubator at 50 ± 0.5°C at three pH values: 4.0; 7.0 and 9.0, during 5 days. The analysis of pH 4.0 buffer solution on Day 5 showed 4.51% hydrolysis, The analysis of pH 7.0 buffer solution on Day 5 showed 1.66% hydrolysis, and the analysis of pH 9.0 buffer solution on Day 5 showed 4.92% hydrolysis. The results obtained clearly indicated that the test item is hydrolytically stable at pH 4.0, pH 7.0 and pH 9.0 buffer solutions under test conditions.

Transformation products:

not measured

Remarks on result:

hydrolytically stable based on preliminary test

Key result

Remarks on result:

hydrolytically stable based on preliminary test

Details on results:

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

Table 2. Summary of test results.

Sample Code	Mean Initial Day Test item Content (mg/L)	Mean Day 5 Test item Content (mg/L)	Degradation (%)
Sample pH 4	17.31	16.53	4.51
Sample pH 7	17.47	17.18	1.66
Sample pH 9	17.47	16.61	4.92

Table 3. Test item concentrations at the start of the test (day 0).

Sample Code	Sample Peak Area (Volts)	Standard Peak Area	Mean Standard Peak Area	Standard Conc. (mg/L)	Dilution Factor	TFMSA Content   (mg/L)	Mean TFMSA Content Obtained (mg/L)
Control pH 4	BLOQ	1885003	1872638	-	-	-	-
Sample pH 4 R1 Rep 1	1610406	1892496		4.01	5.0	17.24	17.31
Sample pH 4 R1 Rep 2	1621242	1870062		4.01	5.0	17.36
Sample pH 4 R2 Rep 1	1615618	1862949		4.01	5.0	17.30
Sample pH 4 R2 Rep 2	1619189	1852678		4.01	5.0	17.34
Control pH 7	BLOQ	-		-	-	-
Sample pH 7 R1 Rep 1	1610173			4.01	5.0	17.24	17.47
Sample pH 7 R1 Rep 2	1610090			4.01	5.0	17.24
Sample pH 7 R2 Rep 1	1667587			4.01	5.0	17.85
Sample pH 7 R2 Rep 2	1638879			4.01	5.0	17.55
Control pH 9	BLOQ			-	-	-
Sample pH 9 R1 Rep 1	1647640			4.01	5.0	17.64	17.47
Sample pH 9 R1 Rep 2	1644194			4.01	5.0	17.60
Sample pH 9 R2 Rep 1	1615753			4.01	5.0	17.30
Sample pH 9 R2 Rep 2	1620021			4.01	5.0	17.35

Table 4. Test item concentrations at the end of the test.

Sample Code	Sample Peak Area (Volts)	Standard Peak Area	Mean Standard Peak Area	Standard Conc. (mg/L)	Dilution Factor	TFMSA Content   (mg/L)	Mean TFMSA Content Obtained (mg/L)
Control pH 4	BLOQ	834899	838346	-	-	-	-
Sample pH 4 R1 Rep 1	1594450	842545		1.78	5.0	16.93	16.53
Sample pH 4 R1 Rep 2	1591443	836197		1.78	5.0	16.89
Sample pH 4 R2 Rep 1	1522596	838152		1.78	5.0	16.16
Sample pH 4 R2 Rep 2	1520222	839939		1.78	5.0	16.14
Control pH 7	BLOQ	-		-	-	-
Sample pH 7 R1 Rep 1	1660610			1.78	5.0	17.63	17.18
Sample pH 7 R1 Rep 2	1642394			1.78	5.0	17.44
Sample pH 7 R2 Rep 1	1595217			1.78	5.0	16.94
Sample pH 7 R2 Rep 2	1573390			1.78	5.0	16.70
Control pH 9	BLOQ			-	-	-
Sample pH 9 R1 Rep 1	1556912			1.78	5.0	16.53	16.61
Sample pH 9 R1 Rep 2	1580429			1.78	5.0	16.78
Sample pH 9 R2 Rep 1	1560602			1.78	5.0	16.57
Sample pH 9 R2 Rep 2	1560805			1.78	5.0	16.57

Validity criteria fulfilled:

yes

Conclusions:

As less than 10 per cent of hydrolysis is observed after 5 days (t½ > 1 year), the test substance was considered hydrolytically stable.

Executive summary:

An hydrolysis study was conducted on the test item, according to OECD TG 111 and EPA OPPTS 835.2130 (Hydrolysis as a function of pH), under GLP conditions. Since the hydrolytic behaviour of the test substance was unknown, a preliminary (Tier 1) test was conducted. Test item sample solutions at pH 4.0, 7.0 and 9.0 were prepared in duplicate in PBS buffer, sterilized by filtering with a 0.2 µm filter and sonicated to remove oxygen. These were kept for 5 days at 50 ± 0.5ºC, protected from light. pH values and sterility were measured at the start and at the end of the test, as well as the test item concentration, which was determined by means of a HPLC-UV method validated according to SANCO/3029/99 rev.4. All validity criteria were met. The analytical measurements at the end of the test showed 4.51, 1.66 and 4.92% hydrolisis under test conditions at pH 4.0, 7.0 and 9.0, respectively. As less than 10 per cent of hydrolysis is observed after 5 days (t½ > 1 year), the test substance was considered hydrolytically stable (no further testing is required).

Description of key information

Key study. Method according to OECD TG 111 / EPA OPPTS 835.2130, GLP study. The analytical measurements at the end of the test showed 4.51, 1.66 and 4.92% hydrolisis under test conditions at pH 4.0, 7.0 and 9.0, respectively. As less than 10 per cent of hydrolysis is observed after 5 days (t½ > 1 year), the test substance was considered hydrolytically stable.