2-[{6-[(4-amino-6-chloro-1,3,5-triazin-2-yl)(methyl)amino]-1-hydroxy-3-sulfonaphthalen-2-yl}diazenyl]naphthalene-1,5-disulfonic acid, lithium sodium salts

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From October 01, 2018 to November 20, 2018

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)

Qualifier:

according to guideline

Guideline:

EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

GLP compliance:

no

Remarks:

conducted at the company internal.

Buffers:

Acetate buffer pH 4, 0.1 M: solution of 0.1 M acetic acid adjusted to pH 4 using 10 N sodium hydroxide. The buffer contains 0.002% (w/v) PREVENTAL BIT 20.
Phosphate buffer pH 7, 0.1 M: solution of 0.1 M potassium dihydrogen phosphate adjusted to pH 7 using 10 N sodium hydroxide. The buffer contains 0.002% (w/v) PREVENTAL BIT 20.
Borate buffer pH 9, 0.1 M: solution of 0.1 M boric acid and 0.1 M potassium chloride adjusted to pH 9 using 10 N sodium hydroxide. The buffer contains 0.002% (w/v) PREVENTAL BIT 20.

Number of replicates:

two

Statistical methods:

System control, data acquisition and data processing were performed using the following programme: Empower version 3.00 (Waters)

Transformation products:

no

% Recovery:

ca. 96.9

pH:

4

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

% Recovery:

ca. 99.6

pH:

7

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

% Recovery:

ca. 99.4

pH:

9

Temp.:

50 °C

Remarks on result:

hydrolytically stable based on preliminary test

pH:

4

Temp.:

25 °C

Hydrolysis rate constant:

0 h-1

DT50:

671 d

Type:

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

pH:

7

Temp.:

25 °C

Hydrolysis rate constant:

0 h-1

DT50:

1 099 d

Type:

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

pH:

9

Temp.:

25 °C

Hydrolysis rate constant:

0 h-1

DT50:

2 194 d

Type:

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

Table 1. Rate constants (k_obs) and half-life times (t_1/2) of the test substance

Temperature [°C]	kobs [hours^-1]			t1/2 [days]
	pH 4	pH 7	pH 9	pH 4	pH 7	pH 9
20	2.30 × 10^-5	1.61 × 10^-5	6.91 × 10^-6	1254	1791	4179
25	4.30 × 10^-5	2.63 × 10^-5	1.32 × 10^-5	671	1099	2194
50	6.91 × 10^-4	2.30 × 10^-4	2.30 × 10^-4	42	125	125

Validity criteria fulfilled:

yes

Conclusions:

According to OECD 111 and EC C.7 test method, the rate constant of CJ302 at 25°C are 4.30× 10-5 hour-1 at pH=4, 2.63× 10-5 hour-1 at pH=7 and 1.32× 10-5 hour-1 at pH=9. And the half-life time of CJ302 at 25°C are 671 days at pH=4, 1099 days at pH=7 and 2194 days at pH=9.

Executive summary:

This test using the procedures outlined in the ECIC Study Plan for 180709-09, OECD 111 (OECD, 2004) and EC C.7 (EC no. 440/2008). In Main study, the mean recoveries of the buffer solutions at t=0 fell within the criterion range of 90-110 % . It demonstrated that the analytical method was adequate to support the hydrolysis study on the test substance. For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 70% and 115% were plotted against time. At all temperatures linear relationships were obtained. The half-life times of the test substance were determined according to the model for pseudo-first order reactions. All logarithms of the relative concentrations were correlated with time using linear regression analysis. The rate constant and half-life time of the test substance at 20 and 50 °C was obtained and the Arrhenius equation was used to determine the rate constant and half-life time at 25°C. Therefore, the rate constant of CJ302 at 25°C are 4.30× 10^-5hour^-1at pH=4, 2.63× 10^-5hour^-1at pH=7 and 1.32× 10^-5hour^-1at pH=9. And the half-life time of CJ302 at 25°C are 671 days at pH=4, 1099 days at pH=7 and 2194 days at pH=9.

Description of key information

The rate constant of CJ302 at 25°C are 4.30× 10^-5hour^-1at pH=4, 2.63× 10^-5hour^-1at pH=7 and 1.32× 10^-5hour^-1at pH=9. And the half-life time of CJ302 at 25°C are 671 days at pH=4, 1099 days at pH=7 and 2194 days at pH=9 (OECD TG 111).

Key value for chemical safety assessment

Half-life for hydrolysis:

1 099 d

at the temperature of:

25 °C

Additional information

In Main study, the mean recoveries of the buffer solutions at t=0 fell within the criterion range of 90-110 % . It demonstrated that the analytical method was adequate to support the hydrolysis study on the test substance. For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 70% and 115% were plotted against time. At all temperatures linear relationships were obtained. The half-life times of the test substance were determined according to the model for pseudo-first order reactions. All logarithms of the relative concentrations were correlated with time using linear regression analysis. The rate constant and half-life time of the test substance at 20 and 50 °C was obtained and the Arrhenius equation was used to determine the rate constant and half-life time at 25°C. Therefore, the rate constant of CJ302 at 25°C are 4.30× 10^-5hour^-1at pH=4, 2.63× 10^-5hour^-1at pH=7 and 1.32× 10^-5hour^-1at pH=9. And the half-life time of CJ302 at 25°C are 671 days at pH=4, 1099 days at pH=7 and 2194 days at pH=9.