Dichlorotricyclo[8.2.2.24,7]hexadeca-1(12),4,6,10,13,15-hexaene, mixed isomers

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

The test samples were analysed for DPX-C active ingredient concentration on 0, 2 and 5 days.
The pH of the samples for preliminary test was determined at 5th day using calibrated pH analyzer.
A separate set of six flasks (2 replicates for each pH) with test item solution was maintained for sterility and pH check at the end of the preliminary test at 50 ± 0.5 °C.

Buffers:

Buffer Solution pH = 4
Reagents. Mono potassium phosphate 500 ml; Sodium Hydroxide 90 mL
Final Volume made up to mark with Distilled water : 1000 mL
Actual pH: 4.03

Buffer Solution pH = 7
Reagents: Mono potassium phosphate 500 mL; Sodium Hydroxide 293.3 ml
Final Volume made up to mark with Distilled water : 1000 mL
Actual pH: 6.98

Buffer Solution pH = 9
Reagents: Boric acid 500 mL; Sodium Hydroxide 213 ml
Final Volume made up to mark with Distilled water : 1000 mL
Actual pH: 9.02

Details on test conditions:

Sterilisation of Glassware and Buffer Solutions:
All the glassware were sterilized by autoclave at 121 ºC and 15 lbs/in2 pressure for 15 to 20 minutes.
The buffer solutions were sterilized by passing through 0.22 µm membrane filter, using sterilised glassware under aseptic condition in a laminar flow chamber

Preparation of Test Item Working Solution (pH= 4, 7 and 9):
Volume (mL) of Test Item Solution: 2.50
Capacity of Volumetric Flask (mL): 250
Concentration (mg/L) Obtained: 0.109
The headspace of the flask was flushed with nitrogen to remove any residual oxygen. The test vessels were sealed with parafilm. All the operations were performed under aseptic condition in a laminar air flow chamber.
The pH of the test solution was recorded using pH meter. The test solutions for analysis were maintained in two replicates.

Preliminary Test:
The buffered test solutions were incubated in a temperature controlled water bath maintained at 50 ± 0.5 °C in dark.
The samples of buffer solutions (pH = 4, 7 and 9) were analyzed by HPLC for quantitation.
A separate set of six flasks (2 replicates for each pH) with test item solution was maintained for sterility and pH check at the end of the preliminary test at 50 ± 0.5 °C.

Determination of pH:
The pH of the samples for preliminary test was determined at 5th day using calibrated pH analyzer.

Monitoring of Sterility:
A volume of 0.1 mL test solution taken from the respective flasks using sterilised pipette and added to the sterile petri-plates. The sterilised nutrient agar medium was poured into the petri-plates and mixed well with sample solution, and then allowed to solidify. The plates were incubated at 37 ± 1 ºC in Digital bacteriological incubator. The observations were recorded at 24 h interval upto 48 h.
The sterility of the samples for preliminary test was checked on 5th day.

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

0.096 mg/L

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

0.094 mg/L

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

0.087 mg/L

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Preliminary study:

The hydrolysis at 50 ± 0.5 °C at pH-4, 7 and 9 was 15.14, 11.12, and 1.79% after 2 days and 6.32, 2.92, and -7.18% after 5 days, respectively. Preliminary test data revealed that the test item is hydrolytically stable at pH-4, 7 and 9 and higher tier tests are not required.

Transformation products:

no

pH:

4

Temp.:

50 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

pH:

7

Temp.:

50 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

pH:

9

Temp.:

50 °C

DT50:

> 1 yr

Remarks on result:

hydrolytically stable based on preliminary test

Calculation of DPX-C (Di-Cloro-Di-p-Xililene) Active Ingredient Concentration

The linearity was established by plotting peak area of reference standard of Dichloro-(2, 2) - paracyclophane (Parylene)solutions against concentrations (mg/L). The slope (b), intercept (a) and correlationcoefficient (r) were calculated.

 

The DPX-C active ingredient concentrations were calculated using the following formula:

DPX-C A.I. concentration, (mg/L)  = (Y-a)/b X D

 

where

Y = Peak area of the sample

A = Intercept

b = Slope of the line

D = Dilution factor

 

The % RSD was calculated using the following formula:

Precision (% RSD) = Standard Deviation/Mean Recovered Concentration X 100           

 

The accuracy (% Recovery) was calculated using the following formula:

% Recovery (Accuracy) = Recovered Concentration /Fortified Concentration X 100

                                                    

Hydrolysis (%) = (Initial concentration - Obtained Concentration) /Initial Concentration X 100

Validity criteria fulfilled:

yes

Conclusions:

DPX-C is hydrolytically stable in acidic, neutral and alkaline condition. The hydrolytic degradation of DPX-C through hydrolysis after 5 days of incubation at 50 ± 0.5 °C at pH 4, 7 and 9 is less than 10%. Therefore, it is concluded that the theoretical half-life of DPX-C is >1 year at 25 ºC and DPX-C is hydrolytically stable at pH 4, 7 and 9.

Description of key information

DPX-C is hydrolytically stable in acidic, neutral and alkaline condition. The hydrolytic degradation of DPX-C through hydrolysis after 5 days of incubation at 50 ± 0.5 °C at pH 4, 7 and 9 is less than 10%. Therefore, it is concluded that the theoretical half-life of DPX-C  is >1 year at 25 ºC and DPX-C  is hydrolytically stable at pH 4, 7 and 9.