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Hydrolysis

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Study period:
September 23, 2019 to December 17, 2019
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
GLP compliance:
no
Remarks:
GLP compliance of China was followed.
Buffers:
Buffer solution (pH 4.0): 4 mL 0.1M sodium hydroxide and 500 mL 0.1M potassium acid phthalate was transferred, dissolved and made up to 1000 mL with ultrapure water.
Transformation products:
no
pH:
4
Temp.:
25 °C
Hydrolysis rate constant:
0.004 d-1
DT50:
169 d
Type:
(pseudo-)first order (= half-life)

Table 1. Hydrolysis results at 50 °C in different pH buffer solutions (pre-test)

Time

(h)

pH Buffer Solution

Mean Concentration

(mg/L)

Hydrolysis rate

(%)

0

4.0

100.162

120

75.703

24.4%

0

7.0

99.950

120

94.901

5.1%

0

9.0

102.478

120

95.166

7.1%

Table 2. Accuracy result of test item in buffer solution of pH4.0 (Recovery)

Fortification level

(mg/L)

Replicates

Measured Concentration

(mg/L)

Recovery

(%)

Mean Recovery

(%)

RSD

(%)

10

1

9.011

90.1

94.0

3.6

2

9.177

91.8

3

9.304

93.0

4

9.725

97.3

5

9.777

97.8

100

1

100.072

100.1

101.7

1.6

2

100.289

100.3

3

101.514

101.5

4

103.034

103.0

5

103.674

103.7

 

Table 3. The results of hydrolysis in buffer solution of pH4.0 at different temperature

Temperature

pH

Hydrolysis reaction rate constant (k)

InCt-t linear regression curve

Correlation coefficient (R2)

Half-life time (T1/2)

20°C

4.0

0.0022 d-1

InCt= -0.0022t + 4.5949

0.9482

315.0 d

25 °C

4.0

0.0041 d-1

InCt= -0.0041t + 4.5967

0.9410

169.0 d

50°C

4.0

0.0452 d-1

InCt= -0.0452t + 4.5916

0.9994

15.3 d

Validity criteria fulfilled:
yes
Conclusions:
According to OECD 111 test method, the half-life time of CJ306 in pH 4.0 buffer solution were 315.0 d, 169.0 d and 15.3 d at 20°C, 25°C and 50°C, respectively.
Executive summary:

This test using the procedures outlined in the CTI Study Plan for G19111003A and OECD 111 (OECD, 2004).The mean recovery was in the range of 90-110%, and the relative standard deviation was less than 10%. The linear correlation coefficient of the regression curve was >0.99. All test validity criteria were met. In the preliminary experiment, the hydrolysis rates of CJ306 at 50 °C were both less than 10% in buffer solutions of pH 7.0 and pH 9.0. Therefore, the main test was only to determine the hydrolysis behavior in buffer solutions of pH 4.0. The results showed that the half-life time of CJ306 in pH 4.0 buffer solution were 315.0 d, 169.0 d and 15.3 d at 20°C, 25°C and 50°C, respectively.

Description of key information

The half-life time of CJ306 in pH 4.0 buffer solution were 315.0 d, 169.0 d and 15.3 d at 20°C, 25°C and 50°C, respectively (OECD TG 111).

Key value for chemical safety assessment

Half-life for hydrolysis:
169 d
at the temperature of:
25 °C

Additional information

The mean recovery was in the range of 90-110%, and the relative standard deviation was less than 10%. The linear correlation coefficient of the regression curve was >0.99. All test validity criteria were met. In the preliminary experiment, the hydrolysis rates of CJ306 at 50 °C were both less than 10% in buffer solutions of pH 7.0 and pH 9.0. Therefore, the main test was only to determine the hydrolysis behavior in buffer solutions of pH 4.0. The results showed that the half-life time of CJ306 in pH 4.0 buffer solution were 315.0 d, 169.0 d and 15.3 d at 20°C, 25°C and 50°C, respectively

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