1,2,4-Benzenetricarboxylic acid, mixed lauryl and octyl triesters

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

April 2015 - June 2015

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Lot No: 04698/MA
Purity: > 98%

Analytical monitoring:

yes

Remarks:

Samples were analysed by Ultra Performance Liquid Chromatography (UPLC).

Details on sampling:

The samples (10.0 mL) were collected, and extracted in 10.0 mL ethyl acetate. The organic phase were dried by rotary evaporation and dissolved in 2.5 mL acetonitrile. Samples were analysed by UPLC-PDA after filtration with 0.22 µm filter membrane. The test substance was quantitatively calculated by the peaks of the chromatograms.

Buffers:

Preparation of Test Solutions

(1) Preparation of buffer solutions
Potassium biphthalate (pH 4.00): 0.4 mL, 0.1 mol/L NaOH and 50 mL, 0.1 mol/L potassium biphthalate was added to 100 mL volumetric flask, and diluted to 100 mL with deionized water (containing no CO).

Phosphate mixtures (pH 7.00): 41.3 mL, 0.0667 mol/L Monopotassium phosphate were added to 100 mL volumetric flask, and diluted to 100 mL with 0.0667 mol/L Disodium phosphate. Potassium tetraborate (pH 9.00): 21.3 mL, 0.1 mol/L NaOH and 50 mL, 0.1 mol/L boric acid was added to 100 mL volumetric flask, and diluted to 100 mL with 0.1 mol/L KC.

(2) Preparation of test substance solutions
The standard stock solution I of the test substance (938 mg/L) was prepared by dissolving 0.0469 g test substance into 50.0 mL acetonitrile.

Preparation of test solutions (10.0 mg/L) with buffer solutions of different pH value. Preliminary concentrations of test solutions were set as 10.0 mg/L to meet the requirement of analytical detection limit, even if test substance hydrolysed 90%. Recovery of the method was able to satisfy the requirements. 107 µL storage solution (938 mg/L) was removed to 10.0 mL volumetric flask respectively, and diluted to 10.0 mL with sterilized buffer solutions (pH 4.00,
7.00, 9.00).

Details on test conditions:

(1) Test temperature
A preliminary test (Tier 1) was conducted at a temperature of (50±0.5) °C.

(2) Light and oxygen
All of the hydrolysis tests were carried out in dark and no oxygen conditions (note: by bubbling the buffer solutions with nitrogen for at least 5 minutes before addition of the test substance).

(3) Test duration
The preliminary test was carried out for 5 days.

(4) Sterilization
All buffer solutions and test vessels were sterilized before the test. The temperature and time were 120°C, 10 Pa and 1h.

(5) Test solutions of different pH values were allocated to six 10 mL test vessels, and incubated at (50±0.5) °C. Reaction solutions of different pH values were analyzed in time intervals of 5 days. The 0 d samples were determined by UPLC-PDA before adding to the biochemical reactor.

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

>= 10.14 - <= 10.21

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

>= 9.62 - <= 10.03

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

>= 10.42 - <= 10.56

Number of replicates:

3

Negative controls:

not specified

Statistical methods:

(1) Hydrolysis rate: Ht = (1-Ct/C0) * 100
Where:
Ht: Hydrolysis rate (%);
Ct: Concentration of sample of t h (mg/L);
C0: Concentration of sample of 0 h (mg/L);
t: time (H).

(2) Relative Standard Deviation (RSD)
The "STEDV function of MS" Office Excel 2010 was used to calculate the SD; RSD is the ratio of the SD against to average of the concentration.

RSD(%) = SD/(average C) * 100

Where:
RSD: Relative Standard Deviation(%);
SD: Standard Deviation(%);
Average C: average of concentration.

Preliminary study:

(1) Working curve
A series of standard solutions with concentration (10.0, 15.0, 20.0, 30.0, 40.0, 50.0 mg/L) were prepared. A power regression equation was obtained with the UPLC response values vs. standard solution concentration, A= l 7002c+ 12688, with good correlation coefficient of 0.9996. The results show that linearity for the concentration range of 10.0 mg/L to 50.0 mg/L is good.

(2) Specificity
The acetonitrile blank sample was determined, and there were no interference peaks in the retention time of test substance (see Figure 2).

(3) Recovery
Measurements obtained from the recovery test were shown in Table 2. Figure 4 and Figure 5.
The recovery rate was 98.6% - 104.9% at the concentration of 10.0 mg/L. The relative standard deviation was between 0.37%-2.15%.
(4) Precision
The standard solution (20.0 mg/L) was detected for 6 times, and the RSD of the concentrations were 1.17 % (see Table 1).
(5) Detection and quantitation limit

The minimum instrument limit of detection is 0.20 mg/Lon the basis of 3 times the SIN, and the limit of quantitation is 0.50 mg/Lon the basis of 10 times the SN.

Transformation products:

not specified

% Recovery:

>= 101.4 - <= 102.1

St. dev.:

0.37

pH:

4

Temp.:

50 °C

Duration:

5 d

% Recovery:

>= 96.2 - <= 100.3

St. dev.:

2.15

pH:

7

Temp.:

50 °C

Duration:

5 d

% Recovery:

>= 104.2 - <= 105.6

St. dev.:

0.67

pH:

9

Temp.:

50 °C

Duration:

5 d

Key result

pH:

4

Temp.:

25 °C

DT50:

> 1 yr

Type:

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

Details on results:

The result of preliminary test which was performed at (50±0.5) °C and pH 4.00, 7.00 and 9.00 was shown as Table 3. The chromatography of test solution was seen as Figure 6 - 8. The concentrations of the test substance in pH 4.00, 7.00, 9 .00 buffer solutions were 9.90, 9.03 and 10.1 mg/L at O d, 10.3, 9.92 and 10.5 mg/L at 5 d, therefore, hydrolysis rates were less than 10% observed in pH 4.00,7.00, and 9.00 after 5 days (T1/2 25°C > 1y).

N/A

Conclusions:

The hydrolysis rates observed were < 10% in pH 4.00, 7.00 and 9.00 at (50±0.5)°C after 5 days, and the hydrolysis half-life was extrapolated to more than 1 year under room temperature (25°C).

Executive summary:

Test for Hydrolysis of test substance as a Function of pH was conducted according to HJ/T 153- 2004, "The guidelines for the testing of chemicals", "The Guidelines for the Testing of Chemicals, Physic-Chemical Properties and Physical Hazards" (the 2" edition, 2013) and with reference to OECD Procedure 111, "Hydrolysis as a Function of pH" etc.

The Preliminary test was performed at (50±0.5)°C and pH 4.00, 7.00, and 9.00. Hydrolysis rates were observed < 10% in pH 4.00, 7.00 and 9.00 after 5 days, and the hydrolysis half-life was extrapolated to more than 1 year under room temperature (25°C).

Description of key information

The hydrolysis rates observed were < 10% in pH 4.00, 7.00 and 9.00 at (50±0.5)°C after 5 days, and the hydrolysis half-life was extrapolated to more than 1 year under room temperature (25°C).

Key value for chemical safety assessment

Half-life for hydrolysis:

1 yr

at the temperature of:

25 °C

Additional information

Test for Hydrolysis of test substance as a Function of pH was conducted according to HJ/T 153- 2004, "The guidelines for the testing of chemicals", "The Guidelines for the Testing of Chemicals, Physic-Chemical Properties and Physical Hazards" (the 2" edition, 2013) and with reference to OECD Procedure 111, "Hydrolysis as a Function of pH" etc.

The Preliminary test was performed at (50±0.5)°C and pH 4.00, 7.00, and 9.00. Hydrolysis rates were observed < 10% in pH 4.00, 7.00 and 9.00 after 5 days, and the hydrolysis half-life was extrapolated to more than 1 year under room temperature (25°C)