Essential oil of Citrus sinensis (Rutaceae) peel, terpene-free

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

mixture rules calculation

Adequacy of study:

key study

Study period:

Study Initiation Date: 11 May 2020;
Study Completion Date: 14 May 2020

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

1. SOFTWARE
iSafeRat® – in Silico Algorithms For Environmental Risk And Toxicity

2. MODEL (incl. version number)
iSafeRat® WatSol v1.9

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
linalool OC(C=C)(CCC=C(C)C)C
decanal O=CCCCCCCCCC
geranial O=CC=C(CCC=C(C)C)C
α-copaene C(CC(C1C(C2)C(C)C)C3(C2)C)=C(C)C31
α-terpineol OC(C(CCC(=C1)C)C1)(C)C
neral O=CC=C(CCC=C(C)C)C
valencene C(C(C(CC1)C)(CC(C(=C)C)C2)C)(=C1)C2
β-copaene C=C1C2C3(C(C2C(CC3)C(C)C)CC1)C
lauric aldehyde O=CCCCCCCCCCCC
citronellal O=CCC(CCC=C(C)C)C
δ-cadinene C(=C(CC1)C)C(C1=C(C2)C)C(C2)C(C)C
perillic aldehyde O=CC(=CCC1C(=C)C)CC1
caryophyllene C(=CCCC(C(C(C1(C)C)C2)C1)=C)(C2)C
β-cubebene C=C1C2C3(C2C(C(C)C)CCC3C)CC1
germacrene D CC1=CCCC(=C)C=CC(CC1)C(C)C
β-elemene C(C(C(C=C)(CCC1C(=C)C)C)C1)(=C)C
β-sinensal O=CC(=CCCC(=CCCC(C=C)=C)C)C
carvone O=C(C(=CCC1C(=C)C)C)C1
citronellol OCCC(CCC=C(C)C)C
decanol OCCCCCCCCCC

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF

5. APPLICABILITY DOMAIN
See attached QPRF

6. ADEQUACY OF THE RESULT
See attached QPRF

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

adapted for Water Accommodated Fraction (WAF)

Deviations:

not applicable

Remarks:

calculation method based QSAR model results

Principles of method if other than guideline:

The water solubility of each constituent was determined using an algorithm based on Quantitative Structure-Property Relationship (QSPR) models which have been validated as QSAR models to be compliant with the OECD recommandations for QSAR modeling (OECD, 2004). The determination was performed using regression method in which validated log KOW values are plotted against the log of subcooled liquid water solubility from studies of high quality. These have been carried out using one of the methods recommended in the OECD 105 guideline or an adaptation of these. Further to this the water solubility of the Water Accomodated Fraction (WAF) is determined by using a calculation method based on equilibrium thermodynamic principles.

GLP compliance:

no

Type of method:

other: calculation method based on QSAR results

Key result

Water solubility:

633 mg/L

Conc. based on:

element (dissolved fraction)

Remarks:

WAF

Temp.:

25 °C

Remarks on result:

other: linalool

Key result

Water solubility:

2.35 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: decanal

Key result

Water solubility:

13.8 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: geranial

Key result

Water solubility:

0.002 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: α-copaene

Key result

Water solubility:

101 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: α-terpineol

Key result

Water solubility:

9.42 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: neral

Key result

Water solubility:

0.005 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: valencene

Key result

Water solubility:

0.003

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: β-copaene

Key result

Water solubility:

0.086 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: lauric aldehyde

Key result

Water solubility:

2.58 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: citronellal

Key result

Water solubility:

0.003 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: δ-cadinene

Key result

Water solubility:

4.77 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: perillic aldehyde

Key result

Water solubility:

0.002 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: caryophyllene

Key result

Water solubility:

0.002 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: β-cubebene

Key result

Water solubility:

0.002 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25

Remarks on result:

other: germacrene D

Key result

Water solubility:

0.001 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: β-elemene

Key result

Water solubility:

0.027 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: β-sinensal

Key result

Water solubility:

22.1 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: carvone

Key result

Water solubility:

2.68 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25

Remarks on result:

other: citronellol

Key result

Water solubility:

0.466 mg/L

Conc. based on:

element (dissolved fraction)

Temp.:

25 °C

Remarks on result:

other: decanol

Conclusions:

A calculation method prediction was performed to determine the water solubility of the consituents of the test item taking into account intermolecular interactions. These values have been determined from the water solubility value when the constituent is considered as a pure substance.

Executive summary:

A calculation method prediction was performed to determine the water solubility of the consituents of the test item. This calculation method predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following the Guideline for Testing of Chemicals No. 105, "Water Solubility" (OECD, 1995) adapted for testing as a mixture using the Water Accomodated Fraction method (WAF). The criterion predicted was the solubility in pure water in mg.L^-1 at 25°C.

 

The water solubility of each constituent was determined using an algorithm based on Quantitative Structure-Property Relationship (QSPR) models which have been validated as QSAR models to be compliant with the OECD recommandations for QSAR modeling (OECD, 2004). The determination was performed using regression method in which validated log K_OW values are plotted against the log of subcooled liquid water solubility from studies of high quality. These have been carried out using one of the methods recommended in the OECD 105 guideline or an  adaptation of these. Further to this the water solubility of the WAF is determined by using a calculation method based on equilibrium thermodynamic principles.

 

A calculation method prediction was performed to determine the water solubility of the consituents of the test item taking into account intermolecular interactions. These values have been determined from the water solubility value when the constituent is considered as a pure substance.

All the constituents of the test item fall within the applicability domain of the model and were reliably predicted for the Water Solubility. Therefore, this endpoint values can be considered valid and fit for purpose.

The WATER SOLUBILITY of the constituents of the test item was determined as follow:

Constituents	water solubility (mg test item.L^-1) at 25°C (pure)	water solubility (mg test item.L^-1) at 25°C (mixed within the test item)
linalool	2.49E+03	6.33E+02
decanal	1.89E+01	2.35E+00
geranial	2.09E+02	1.38E+01
α-copaene	2.28E-02	2.16E-03
α-terpineol	2.17E+03	1.01E+02
neral	2.09E+02	9.42E+00
valencene	7.72E-02	4.71E-03
β-copaene	5.17E-02	3.36E-03
lauric aldehyde	1.25E+00	8.60E-02
citronellal	1.10E+02	2.58E+00
δ-cadinene	8.84E-02	2.92E-03
perillic aldehyde	6.51E+02	4.77E+00
caryophyllene	7.15E-02	2.25E-03
β-cubebene	5.17E-02	1.68E-03
germacrene D	6.77E-02	1.54E-03
β-elemene	4.31E-02	8.86E-04
β-sinensal	2.59E+00	2.68E-02
carvone	1.06E+03	2.21E+01
citronellol	2.25E+02	2.68E+00
decanol	4.17E+01	4.66E-01

No uncertainty estimation is provided.

Description of key information

The water solubility of the major constituents mixed within the test item at 25°C (20 constituents corresponding to more than 82% of the composition) are ranging between 0.000886 and 633 mg/L.

Additional information

No study was conducted on the oil itself.

The test item is a natural complex substance (NCS). It is a mixture of several constituents, but 20 of them represent more than 82% of the mixture.

Water solubility of these constituents were estimated using a valid calculation method prediction, compliant with the OECD recommandations for QSAR modeling (OECD, 2004), taking into account intermolecular interactions between the constituents of the mixture. These values have been determined from the water solubility value when the constituent is considered as a pure substance.

All the constituents of the test item fall within the applicability domain of the model and were reliably predicted for the Water Solubility. Therefore, this endpoint values can be considered valid and fit for purpose.

Finally, the water solubility of these constituents was reported below:

 

The WATER SOLUBILITY of the constituents of the test item was determined as follow:

Constituents	water solubility (mg test item.L^-1) at 25°C (pure)	water solubility (mg test item.L^-1) at 25°C (mixed within the test item)
linalool	2.49E+03	6.33E+02
decanal	1.89E+01	2.35E+00
geranial	2.09E+02	1.38E+01
α-copaene	2.28E-02	2.16E-03
α-terpineol	2.17E+03	1.01E+02
neral	2.09E+02	9.42E+00
valencene	7.72E-02	4.71E-03
β-copaene	5.17E-02	3.36E-03
lauric aldehyde	1.25E+00	8.60E-02
citronellal	1.10E+02	2.58E+00
δ-cadinene	8.84E-02	2.92E-03
perillic aldehyde	6.51E+02	4.77E+00
caryophyllene	7.15E-02	2.25E-03
β-cubebene	5.17E-02	1.68E-03
germacrene D	6.77E-02	1.54E-03
β-elemene	4.31E-02	8.86E-04
β-sinensal	2.59E+00	2.68E-02
carvone	1.06E+03	2.21E+01
citronellol	2.25E+02	2.68E+00
decanol	4.17E+01	4.66E-01

No uncertainty estimation is provided.

Considering that, as a UVCB with constituents of different solubility, the global solubility of the substance will depend on the composition and the loading rate (with varying ratio of constituents in the dissolved phase), we reported the water solubility of the major components of the substance at 25°C and no single key value was retained (nor calculated weighted WS nor worst-case)