Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Phototransformation in air

Currently viewing:

Administrative data

Link to relevant study record(s)

Referenceopen allclose all

Endpoint:
phototransformation in air
Type of information:
experimental study
Adequacy of study:
other information
Study period:
approx. 1995
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Secondary literature; Peer-reviewed dossier
Principles of method if other than guideline:
Calculation with Graphical Exposure Modelling System (GEMS)
GLP compliance:
no
Estimation method (if used):
Graphical Exposure Modelling System (GEMS)
Details on test conditions:
Sensitiser (for indirect photolysis): O3
Reference substance:
not specified
DT50:
ca. 23 min
Test condition:
1.0E+12 O3 molecules/cm3

Rate constant: kO3 = 5 E-16 cm3 molec-1 s-1 at 25 °C
Assuming a concentration of 1 E12 O3-molecules/cm3, a half-life of 23 min is calculated.

Validity criteria fulfilled:
yes
Conclusions:
The rate constant for the O3 sensitized photodegradation of isophorone is 5.0E-16 cm3/(molecule * s). At 1.0E+12 O3 molecules / cm3, this corresponds to a half-life of 23 minutes.
Executive summary:

The rate constant for the O3 sensitized photodegradation of isophorone was calculated as 5.0E-16 cm3/(molecule * s). At 1.0E+12 O3 molecules / cm3, this corresponds to a half-life of 23 minutes.

Endpoint:
phototransformation in air
Type of information:
experimental study
Adequacy of study:
other information
Study period:
approx. 1999
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study in accordance with generally accepted scientific standards and described in sufficient detail
Principles of method if other than guideline:
relative rate method, OH sensitized photooxidation
GLP compliance:
no
Light source:
other: UV strip lights (Philips, UK)
Details on test conditions:
Sensitiser (for indirect photolysis): OH
TEST TYPE:
- Test medium: synthetic air
- Test system: Smog chamber
- Concentration of test substance: 2 - 8 ppm
- Generation of sensitizer: methyl nitrite
- Pressure: atmospheric
- Temperature: 298 K
DURATION: 60-75 min
Reference substance:
yes
Remarks:
cyclohexene
DT50:
ca. 16 h
Test condition:
500,000 OH radicals/cm³
Transformation products:
not measured
Results with reference substance:
A rate constant for the reference substance of k = 6.77 +- 1.35 E-11 cm3 / (molecules * s) was assumed in the evaluation.

Relative rate constants: k(isophorone) / k(reference substance) = 0.35 +- 0.07


Rate constant (isophorone): kOH = (2.4 +- 0.7) E-11 cm3 molec-1 s-1
Assuming a concentration of 500000 OH-radicals/cm3, a half-life of 16 h is calculated.

Validity criteria fulfilled:
yes
Conclusions:
The rate constant for the OH sensitized photodegradation of isophorone is 2.4E-11 cm3/(molecule * s). At 500,000 OH radicals / cm3, this corresponds to a half-life of 16 hours.
Executive summary:

The rate constant for the OH sensitized photodegradation of isophorone was determined in a relative rate experiment as 2.4E-11 cm3/(molecule * s). At 500,000 OH radicals / cm3, this corresponds to a half-life of 16 hours.

Description of key information

The rate constant for the O3 sensitized photodegradation of isophorone was calculated as 5.0E-16 cm3/(molecule * s). At 1.0E+12 O3 molecules / cm3, this corresponds to a half-life of 23 minutes.
The rate constant for the OH sensitized photodegradation of isophorone was determined in a relative rate experiment as 2.4E-11 cm3/(molecule * s). At 500,000 OH radicals / cm3, this corresponds to a half-life of 16 hours.

Key value for chemical safety assessment

Half-life in air:
23 min
Degradation rate constant with OH radicals:
0 cm³ molecule-1 s-1

Additional information

Dissipation half-life 23 minutes = 0.016 days