Reaction mass of 1-(2,6,6-trimethyl-1-cyclohexen-1-yl)pent-1-en-3-one and 1-(2,6,6-trimethyl-2-cyclohexen-1-yl)pent-1-en-3-one

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From May 09,2017 to May 18,2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

This information is used for read-across to reaction mass of 1-(2,6,6-trimethyl-1-cyclohexen-1-yl)pent-1-en-3-one and 1-(2,6,6-trimethyl-2-cyclohexen-1-yl)pent-1-en-3-one.

Qualifier:

according to guideline

Guideline:

OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Specific details on test material used for the study:

Aspect: Colourless to yellow liquid
Lot No: VE00437050
Expiration date: July 16,2018
Purity: 86.1% Iso-alpha-isomer

Test temperature:

35°C

Details on study design: HPLC method:

EQUIPMENT AND CONDITIONS
HPLC equipment: Perkin Elmer (series 200) HPLC system comprising: a high pressure pump (module N2910102, serial number: 291N8051901A), an auto-sampler (modure N2930100, serial number: OVH0802151130), a refractive index detector (series 200a, serial number 1125829).

Column: 250mm x 4.6mm, Nucleodur 100-5CN-RP serial number E15120578 batch 34514011
Mobile phase: Methanol / Water 55/45 (v/v)
Flow rate: 1.0 ml/min
Column temperature: 35°C
Injected volume: 100 microliters

REFERENCE SUBSTANCES
6 chosen having log Koc from 1.45 to 5.63 and Formamide used as an unretained compound for the determination of the “dead time” t0.
1- 2-nitrobenzamide
2- Methyl benzoate
3- Naphthalene
4- 1,2,3-trichlorobenzene
5- Phenanthrene
6- 4-4’-DDT

HPLC PROCEDURE
A solution of the test substance was prepared (10.0 mg in 25 ml methanol/water 55/45 v/v).
After equilibration of the HPLC system, the calibration mixture was injected first, followed by the test chemical solution twice and the calibration mixture again. Retention times were measured and averaged and the decimal logarithms of the capacity factors k were calculated. The linear regression parameters of the relationship long Koc = f(log k) were also calculated from the data obtained with the calibration mixture and, therewith, log Koc of the test substance was deter-mined from its measured capacity factor.

Key result

Sample No.:

#1

Type:

log Koc

Value:

3.6 dimensionless

Temp.:

35 °C

Details on results (HPLC method):

- The chromatograms of Isoraldeine 95 show one peak at an average retention time of 8.915 minutes, corresponding to an adsorption coefficient (log value) of 3.6.
- The determination was performed at 35 °C (temperature of the column) but the value obtained can be considered to represent the value at an unspecified, probably ambient temperature since no mention is made in the guidelines of the temperature at which the tabulated reference substances log Koc values were determined. Adsorption coefficients of the test and reference substances are assumed to vary with temperature in the same way.

Transformation products:

not measured

Remarks:

not applicable for the OECD 121 HPLC method

Validity criteria fulfilled:

yes

Conclusions:

The adsorption coefficient (Koc) on soil and on sewage sludge of ISORALDEINE 95 was determined by the Reverse Phase High Performance Liquid Chromatographic Method according to the OECD Guidelines for Testing of Chemicals, Method No. 121. The result is: Adsorption coefficient (log value) of ISORALDEINE 95: log Koc = 3.6.

This value is being used in to read-across to the registration substance, “Reaction Mass of 1-(2,6,6-trimethyl-1-cyclohexen-1-yl)pent-1-en-3-one and 1-(2,6,6-trimethyl-2-cyclohexen-1-yl)pent-1-en-3-one” (see target endpoint record)

Executive summary:

The adsorption coefficient (Koc) on soil and on sewage sludge of ISORALDEINE 95 was determined by the Reverse Phase High Performance Liquid Chromatographic Method according to the OECD Guidelines for Testing of Chemicals, Method No. 121.

The result is: Adsorption coefficient (log value) of ISORALDEINE 95: log Koc = 3.6.

Reference 2

Endpoint:

adsorption / desorption: screening

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Rationale for reliability incl. deficiencies:

other: read-across from a guideline study

Justification for type of information:

The read-across is based on the hypothesis that the target and source substance have similar adsorption/desorption properties as a result of structural similarity. They consist of structurally similar isomers that belong to the same chemical class (e.g. ketones) and have similar log Kow values.

QSARs for soil and sediment sorption are typically based on the n-octanol-water partition coefficient (Kow). The influence of Kow is logical because hydrophobic interactions are the most dominant type of interactions between non-polar organic chemicals and the soil organic carbon. On the other hand, however, it is also obvious that chemicals with more polar groups may interact with the soil via more specific (electronic type) interactions. In those cases, Kow will not be the only crucial parameter in the estimation of Koc. Because of this, different models are developed and proposed for different classes of chemicals. Most of these class specific models are still based on Kow.

The measured log Kow for the source substance is 4.6 (REACH registration for EC 695-097-5) and that for the registered substance 4.7 and 4.9. Using these measured log Kow values as input into an appropriate QSAR for soil and sediment sorption gives estimated log Koc values of 3.41 (source substance), 3.46 (target, constituent 1) and 3.57 (target, constituent 2) - see attached justification file. This supports the similarity of the adsorption/desorption potential of the source and target substance and use of read-across from the measured value of log Koc 3.6 to address this endpoint in the REACH registration of “Reaction Mass of 1-(2,6,6-trimethyl-1-cyclohexen-1-yl)pent-1-en-3-one and 1-(2,6,6-trimethyl-2-cyclohexen-1-yl)pent-1-en-3-one” (target substance).

Reason / purpose for cross-reference:

read-across source

Key result

Type:

log Koc

Value:

3.6 dimensionless

Temp.:

35 °C

Remarks on result:

other: read-across from Isoraldeine 95

Details on results (HPLC method):

The determination was performed at 35 °C (temperature of the column) but the value obtained can be considered to represent the value at an unspecified, probably ambient temperature since no mention is made in the guidelines of the temperature at which the tabulated reference substances log Koc values were determined. Adsorption coefficients of the test and reference substances are assumed to vary with temperature in the same way.

Validity criteria fulfilled:

yes

Conclusions:

Log Koc of reaction mass of 1-(2,6,6-trimethyl-1-cyclohexen-1-yl)pent-1-en-3-one and 1-(2,6,6-trimethyl-2-cyclohexen-1-yl)pent-1-en-3-one is 3.6 based on read across from Isoraldeine 95.

Description of key information

Log Koc of reaction mass of 1-(2,6,6-trimethyl-1-cyclohexen-1-yl)pent-1-en-3-one and 1-(2,6,6-trimethyl-2-cyclohexen-1-yl)pent-1-en-3-one is 3.6 based on read across from Isoraldeine 95, The log Koc of 3.6, corresponds to a Koc of 3981.

Key value for chemical safety assessment

Koc at 20 °C:

3 981

Additional information

A study to assess adsorption/desorption is not available for the registered substance. However, a valid study exists for the analogue substance, Isoraldeine 95. The read-across is based on the hypothesis that the target and source substance have similar adsorption/desorption properties as a result of structural similarity. They consist of structurally similar isomers that belong to the same chemical class (e.g. ketones) and have similar log Kow values.

QSARs for soil and sediment sorption are typically based on the n-octanol-water partition coefficient (Kow). The influence of Kow is logical because hydrophobic interactions are the most dominant type of interactions between non-polar organic chemicals and the soil organic carbon. On the other hand, however, it is also obvious that chemicals with more polar groups may interact with the soil via more specific (electronic type) interactions. In those cases, Kow will not be the only crucial parameter in the estimation of Koc. Because of this, different models are developed and proposed for different classes of chemicals. Most of these class specific models are still based on Kow.

The measured log Kow for the source substance is 4.6 (REACH registration for EC 695-097-5) and that for the registered substance 4.7 and 4.9. Using these measured log Kow values as input into an appropriate QSAR for soil and sediment sorption gives estimated log Koc values of 3.41 (source substance), 3.46 (target, constituent 1) and 3.57 (target, constituent 2). This supports the similarity of the adsorption/desorption potential of the source and target substance and use of read-across from the measured value of log Koc 3.6 to address this endpointin the REACH registration of “Reaction Mass of 1-(2,6,6-trimethyl-1-cyclohexen-1-yl)pent-1-en-3-one and 1-(2,6,6-trimethyl-2-cyclohexen-1-yl)pent-1 -en-3-one” (target substance). The source study is summarised below.

The adsorption coefficient (Koc) on soil and on sewage sludge of ISORALDEINE 95 was determined by the Reverse Phase High Performance Liquid Chromatographic Method according to the OECD Guidelines for Testing of Chemicals, Method No. 121. The determination was performed at 35 °C (temperature of the column) but the value obtained can be considered to represent the value at an unspecified, probably ambient temperature since no mention is made in the guidelines of the temperature at which the tabulated reference substances log Koc values were determined. Adsorption coefficients of the test and reference substances are assumed to vary with temperature in the same way. The chromatograms of ISORALDEINE 95 show one peak which was determined to have a Log Koc value of 3.6. This corresponds to a Koc value of 3981.