Everzol Red CDN Crude

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From July 4, 2014 to May 5, 2015

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.

Analytical monitoring:

yes

Remarks:

Digital Electronic Indictors + S.S.R. with PID automatic calculation capability

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 dihydrogenphosphate 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 5.00 (Waters, Milford, MA, USA)

Preliminary study:

At pH 4 a degree of hydrolysis of ≥ 40% after 5 days was observed. The mean recovery of the buffer solutions at pH 9 at t=0 was non detected and was therefore outside the criterion range of 90-110%. Because multiple degradation products were observed at pH 4 and pH 7 and pH 9 and no test substance was detected in the test samples (i.e. a degree of hydrolysis of ≥ 10% ) after 5 days it was decided that the higher Tier test was required to determine the half-life time of the test substance.

Transformation products:

no

% Recovery:

99.3

pH:

4

Temp.:

50 °C

Duration:

0 h

% Recovery:

82.4

pH:

7

Temp.:

50 °C

Duration:

0 h

pH:

9

Temp.:

50 °C

Duration:

0 h

Remarks on result:

not determinable

Remarks:

The low recoveries are probably caused by unstable at pH 9 .

pH:

4

Temp.:

25 °C

Hydrolysis rate constant:

0 h-1

DT50:

173 d

Type:

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

pH:

7

Temp.:

25 °C

Hydrolysis rate constant:

1.06 h-1

DT50:

39.3 min

Type:

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

pH:

9

Remarks on result:

not determinable

Table 1. Preliminary test-hydrolysis of the test substance at pH 4, pH 7 and pH 9

pH code	Sampling time	Analysed concentration (mg/l)	Degree of hydrolysis (%)		Actual pH
			Individual	Mean
pH 4	0 hours	99.3	－	－	3.90
		101	－		3.90
	5 days	45.5	55.7	57.5	3.90
		41.1	59.6		3.90
pH 7	0 hours	107	－	－	7.10
		107	－		7.10
	5 days	N.D.	N.D.	N.D.	7.10
		N.D.	N.D.		7.10
pH 9	0 hours	N.D.	－	－	9.00
		N.D.	－		9.00
	5 days	N.D.	N.D.	N.D.	8.95
		N.D.	N.D.		8.95

N.D. means non detected.

 

Table 2. Preliminary test-Recoveries

pH code	Nominal concentration (mg/l)	Analysed concentration (mg/l)	Recovery (%)	Mean recovery (%)
pH 4	309	305	98.6	99.3
	309	309	100
pH 7	107	101	94.3	82.4
	107	75.4	70.5
pH 9	115	N.D.	N.D.	N.D.
	115	N.D.	N.D.

N.D. means non detected.

 

Table 3. Rate constants (k_obs) and half-life time (t_½) at pH 4 and pH 7

Temperature (°C)	kobs(hours^-1)		t½
	pH 4	pH 7	pH 4	pH 7
20	1.03× 10^-4	8.31× 10^-1	280 days	50.0 mins
25	1.67× 10^-4	1.06	173 days	39.3 mins
40	6.43× 10^-4	2.09	44.9 days	19.9 mins
50	4.61× 10^-2	2.11	15.0 days	19.7 mins

 

Validity criteria fulfilled:

yes

Conclusions:

According to OECD 111 and EC C.7 test method, the rate constant (kobs) of Everzol Red CDN Crude at 25°C are 1.67 × 10-4 and 1.06 hour-1 respectively at pH=4 and pH=7. And the half-life time of Everzol Red CDN Crude at 25°C are 173 days and 39.3 mins respectively at pH=4 and pH=7.

Executive summary:

This test using the procedures outlined in the Everlight Study Plan for 140623-11, OECD 111 (OECD, 2004) and EC C.7 (EC no. 440/2008).

In the preliminary test, the multiple degradation products were observed at pH=4 and pH=7 and pH=9 and no test substance was detected in the test samples (i.e. a degree of hydrolysis of ≥ 10 % ) after 5 days it was decided that the higher Tier test was required to determine the half-life time of the test substance. In main study,the mean recoveries of the buffer solutions at pH=4 and 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. At pH=7, the mean recoveries of the buffer solutions at t=0 fell within the criterion range of 70-110 %. Analysis of different waiting times cause two samples at the same time have 20-30 % difference. At pH=9, the mean recovery of the buffer solutions at t=0 was non detected and was therefore outside the criterion range of 90-110 %. The low recoveries are probably caused by unstable at pH=9. For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 10% and 90% 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 (kobs) and half-life time of the test substance at each temperature was obtained and the Arrhenius equation was used to determine the rate constant and half-life time at 25°C.Therefore, the rate constant (kobs) of Everzol Red CDN Crude at 25°C are 1.67× 10^-4 and 1.06 hour^-1 respectivelyat pH=4 and pH =7. And the half-life time of Everzol Red CDN Crude at 25°C are 173 days and 39.3 mins respectively at pH=4 and pH=7.

Description of key information

The rate constant (kobs) of Everzol Red CDN Crude at25°C are 1.67× 10^-4 and 1.06 hour^-1 respectivelyat pH=4 and pH=7. And the half-life timeof Everzol Red CDN Crude at25°C are 173 days and 39.3 mins respectively at pH=4 and pH=7(OECD TG111).

Additional information

In the preliminary test, the multiple degradation products were observed at pH=4 and pH=7 and pH=9 and no test substance was detected in the test samples (i.e. a degree of hydrolysis of ≥ 10% ) after 5 days it was decided that the higher Tier test was required to determine the half-life time of the test substance.In Main study,the mean recoveries of the buffer solutions at pH=4 and 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. At pH=7, the mean recoveries of the buffer solutions at t=0 fell within the criterion range of 70-110%. Analysis of different waiting times cause two samples at the same time have 20-30% difference. At pH=9, the mean recovery of the buffer solutions at t=0 was non detected and was therefore outside the criterion range of 90-110%. The low recoveries are probably caused by unstable at pH=9. For testing of pseudo-first order kinetics the mean logarithms of the relative concentrations between 10% and 90% 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 (kobs) and half-life time of the test substance at each temperature was obtained and the Arrhenius equation was used to determine the rate constant and half-life time at 25°C. Therefore, the rate constant (kobs) of Everzol Red CDN Crude at 25°C are 1.67× 10^-4 and 1.06 hour^-1 respectivelyat pH=4 and pH=7. And the half-life time of Everzol Red CDN Crude at 25°C are 173 days and 39.3 mins respectively at pH=4 and pH=7.