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Hydrolysis

HYDROWIN v2.00 program of Estimation Programs Interface prediction model was used to predict the hydrolysis half-life of test chemical. The estimated half-life of test chemical was determined to be 4.717 yrs and 172.299 days at pH 7.0 and 8.0 (at 25°C) respectively, indicating that it is stable in water.

Additional information

Hydrolysis

Predicted data for the test chemical and various supporting weight of evidence studies for its structurally similar and functionally similar read across substance were reviewed for the bioaccumulation end point which are summarized as below:

 

In a prediction done using the HYDROWIN v2.00 program of Estimation Programs Interface, the hydrolysis half-life of test chemical was predicted. The estimated half-life of test chemical was determined to be 4.717 yrs and 172.299 days at pH 7.0 and 8.0 (at 25°C) respectively.

 

In a supporting weight of evidence study, hydrolysis study was carried out for determining the half-life of the test chemical (Spencer M. Steinberg and Francis Lena, 1995). Stock solutions of test chemical (0.1 g/ml) was prepared in acetonitrile. A small portion of the test chemical stock solution (50 µl) was injected into 100ml of the pH buffer. Concentration of the test chemical used during the study was 50 mg/l. The 100 ml buffer solutions were then divided into 6-10 screw cap vials. The vials were placed in a constant temperature aluminium block or in an oven at 30°-120°C. Vials were removed at various times and immediately frozen to stop hydrolysis. The ratios of acid to ester, in the heated samples, were determined using High Performance Liquid Chromatography (HPLC). The HPLC system consisted of a Milton-Roy minipump, a Reodyne 7410 injector with a 20µL sample loop. 5µ C18 analytical column (25 x 0.46 cm) used was purchased from Alltech Associates. The mobile phase consisted of a 50:50 mixture of acetonitrile and water, with 0.10% (V/V) H3PO4 added to control the eluant pH. Kratos Spectroflow Model 747 ultraviolet/visible detector was used as a detector. The column flow rate was maintained at 1 ml/min. The column effluent was monitored at 210 or 254 nm and the peak areas were recorded with a Hewlett-Packard 3390 integrator. Phosphate buffer (conc. 0.2 M, 0.05M, 01 M and 0.2 M, pH 5, 6 & 7) was used in the study. Buffer pHs were adjusted by addition of NaOH or HCI, and their ionic strengths were adjusted to 0.5 M using NaCl. The pseudo first order rate constants for hydrolysis of test chemical are 0.32± 0.01 h -1, 0.32±0.02 h -1 and 0.36±0.03h -l, for the 0.2, 0.1 and 0.05 M buffers respectively. The half-life value of test chemical was determined to be 1.8 years at pH 8 and at a temperature 10°C.

 

In an another study from authoritative database (2018), the half-life of the test chemical was determined using an estimated pseudo-first order hydrolysis rate constant of 0.00000021/sec. The half-life of test chemical was determined to be 38 days at pH 7 and a temperature of 25°C, respectively.

 

For the test chemical, the half-life and base catalyzed second order hydrolysis rate constant was determined using a structure estimation method of the test chemical. The second order hydrolysis rate constant of test chemical was determined to be 0.16L/mol-sec with a corresponding half-lives of 1.4 yrs and 51 days at pH 7 and 8, respectively.

 

On the basis of above results for test chemical, it can be concluded that the test chemical was hydrolytically stable.

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