Undecanal

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2010-07-23 to 2010-08-23

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Three reliable data sources are available for partition coefficient octanol-water. In absence of any indications in favour of any of these studies, a weight of evidence approach considering the accuracy of the applied method is deemed to be most appropriate.

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Version / remarks:

adopted April 13, 2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient - HPLC Method)

Version / remarks:

EC Council Regulation 2008/440/EC

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7570 (Partition Coefficient, n-octanol / H2O, Estimation by Liquid Chromatography)

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

4.4

Temp.:

35 °C

pH:

7

Remarks on result:

other: No limitation for column temperature according to OECD 117: Kow of test and reference substances assumed to vary with T in the same way.

Remarks:

Average of two determinations (1: 4.374; 2: 4.375)

Details on results:

The determination was performed at 35 °C (temperature of the column), but the value obtained above 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 Pow values were determined. Partition coefficients of the test and reference substances are assumed to vary with temperature in the same way.

Results from HPLC determination:

REFERENCE SUBSTANCES	log Pow	t_R1	t_R2	t_Rm	k	log k
Thiourea		2.364	2.367	2.37
Benzyl alcohol	1.1	2.715	2.720	2.72	0.149	-0.827
Benzene	2.1	3.664	3.669	3.67	0.550	-0.260
Toluene	2.7	4.392	4.399	4.40	0.858	-0.066
1,4-Dichlorbenzene	3.4	5.261	5.269	5.27	1.226	0.088
Cumene	3.7	6.128	6.137	6.13	1.592	0.202
1,2,4-Trichlorobenzene	4.2	7.577	7.586	7.58	2.205	0.343
Fluoranthene	5.1	12.534	12.527	12.53	4.297	0.633

t_R1, t_R2, t_Rm: retention times (first measurement, 2nd measurement, average)

k = (t_R/t_0)-1; t_0 = capacity factor ("dead time''), i.e. retention time of thiourea;

Linear regression parameters:       log Pow = a * log k + b

Correlation coefficient r = 0.9867;

a = 2.8162;       b= 3.1400

Results for test item:

	t_R1	t_R2	t_Rm	k	log k	log Pow
n-undecanal	8.872	8.873	8.87	2.7508	0.4395	4.4

The log Pow values for the test item fall within a range of +/- 0.10 log units (k1 = 2.74346; log Kow_1 = 4.374; k2= 2.74388; log Kow_2 = 4.375). Thus, the test is satisfactory.

Conclusions:

log Kow (OECD 117; HPLC method): 4.40

Executive summary:

The Partition Coefficient n-octanol / water of n-undecanal was determined compliant with GLP by the Reverse Phase High Performance Liquid Chromatographic Method according to the OECD Guidelines for Testing of Chemicals, Method No. 117 .

The result is:

Partition coefficient n-octanol / water of n-undecanal:

log Pow = 4.4 (n=2: 4.374; 4.375)

Reference 2

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2009-11-11 to 2010-02-25

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Three reliable data sources are available for partition coefficient octanol-water. In absence of any indications in favour of any of these studies, a weight of evidence approach considering the accuracy of the applied method is deemed to be most appropriate.

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Version / remarks:

adopted on 13 April 2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient - HPLC Method)

Version / remarks:

Directive 92/69/EEC, Official Journal L 383 A 1992

Deviations:

no

GLP compliance:

yes

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

5.1

Temp.:

25 °C

Remarks on result:

other: mean value from two determinations (giving identical results)

Remarks:

pH not stated, however, test item not ionisable

Results of the HPLC measurements for reference compounds (for nomenclature, see materials and methods section) and test item:

Sample no.^1)	t_R1 [min]	t_R2 [min]	t_R [min]	k'	log k'(x)	log Pow (y)
0	1.18	1.18	1.18	--	--	--
1	1.68	1.68	1.68	0.424	-0.373	1.7^2)
2	2.50	2.50	2.50	1.119	0.049	3.2^2)
3	5.32	5.33	5.33	3.517	0.546	4.1^3)
4	6.52	6.52	6.52	4.525	0.656	4.6^2)
5	15.55	15.56	15.56	12.186	1.086	6.5^2)
6	68.35	68.39	68.37	56.941	1.755	7.9^4)
Test item	8.05			5.822	0.765	5.10^5)
Test item		8.07		5.839	0.766	5.10^5)
Mean value						5.1

1) For the names of the reference compounds see materials section.

2) Results from the OECD guideline for the testing of chemicals No. 117: "Partition Coefficient (n-octanol/water), HPLC method" (13 April 2004).

3) M. Harnisch et al.: J. Chromatogr. 282, 315-333 (1983)

4) W. Klein et al.: Chemosphere Vol 17 No.2, 361-386 (1988)

5) Interpolated from linearized function log Pow = f(log k' ) of the calibration data.

Linear regression function from plot log Pow (ordinate) against log k' (abscissa):

y = 2.9555 * x + 2.8347

The linear regression of the log k' of the calibration substances against their log Pow has a correlation coefficient of r = 0.9915.

The resulting log P values for the test item from two determinations fall within the range of +/- 0.1 log units. Thus, the test is satisfactory.

Conclusions:

log Pow (OECD 117, HPLC method): 5.10 (25 °C)

Executive summary:

The partition coefficient n-octanol / water (Pow) of the test item was determined compliant with GLP according to OECD guideline no. 117 [adopted on 13. April 2004] and EU test method A.8 [Directive 92/69/EEC, Official Journal L 383 A 1992] with the HPLC method.

Partition coefficient n-octanol / water (Pow): Pow = 1.26 x 10E5; log Pow = 5.1 (AQURA, 2010).

Reference 3

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2010-10-29 for T10532 (octanol solubility); 2009-11-11 to 2010-02-25 for T10309 (water solubility)

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Octanol solubility was not determined compliant with GLP

Justification for type of information:

Three reliable data sources are available for partition coefficient octanol-water. In absence of any indications in favour of any of these studies, a weight of evidence approach considering the accuracy of the applied method is deemed to be most appropriate.

Reason / purpose for cross-reference:

other: Reference to endpoint study record on determination of solubility in water

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Version / remarks:

COMMISSION REGULATION (EC) No 440/2008 of 30 May 2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Product Properties Test Guidelines OPPTS 830.6319 - Miscibility (EPA).

Principles of method if other than guideline:

The ratio of solubilities in n-octanol and in water is used as the best estimate of the partition coefficient.

GLP compliance:

no

Remarks:

Water solubility was determined according to GLP; octanol solubility was determined in a reliable non-GLP study.

Type of method:

other: The ratio of solubilities in n-octanol and in water is used as the best estimate of the partition coefficient.

Partition coefficient type:

octanol-water

Analytical method:

other: Solubility in octanol: determined by visual examination; solubility in water: described in detail in ESR IUCLID section 4.8: OXEA Company Data (+2010 Water solubility RL1)

Key result

Type:

log Pow

Partition coefficient:

4.84

Temp.:

20 °C

pH:

7

Remarks on result:

other: calculated from solubility in water and n-octanol

Type:

Pow

Partition coefficient:

69 025

Temp.:

20 °C

pH:

7

Remarks on result:

other: calculated from solubility in water and n-octanol

Results for solubility of n-undecanal in n-octanol according to OPPTS 830.6319

n-Undecanal: n-Octanol (w/w)	Appearance (30 min at 20°C)
03:01	miscible
01:01	miscible
01:03	miscible

Conclusion: n-undecanal is fully miscible with n-octanol.

The numerical value for the solubility as gram n-undecanal per liter solution is therefore the density of n-undecanal:

Solubility of n-undecanal in n-octanol: 0.8283 g/mL = 828.3 g n-undecanal/L n-octanol at 20 °C.

Calculation of the n-octanol/water partition coefficient from solubilities in pure water and n-octanol

Solubility in water (AQURA, 2010; OECD 105, flask method): 12 mg/L at 20 °C;

Solubility in n-octanol (Clariant, 2010, OPPTS 830.6319): 828.3 g/L at 20°C;

Kow = solub_n-octanol / solub_water = 69025;

log Kow = log (solub_n-octanol / solub_water) = log(69025) = 4.84

Conclusions:

log Kow (EU method A.8; ratio of solubility in n-octanol and water): 4.84 at 20°C

Executive summary:

The partition coefficient n-octanol / water (Pow) of the test item was determined according to EU test method A.8 [COMMISSION REGULATION (EC) No 440/2008 of 30 May 2008] for individual solubilities in n-octanol and water.

Solubility in water of n-undecanal was determined in the reliable GLP compliant key study on water solubility (AQURA, 2010; OECD 105, flask method) to be 12 mg/L at 20 °C;

Solubility of n-undecanal in n-octanol was determined according to Product Properties Test Guidelines OPPTS 830.6319 - Miscibility (EPA). n-Undecanal was found to be fully miscible in n-octanol. Concluding, solubility in n-octanol equals the density of n-undecanal:

Solubility of n-undecanal in n-octanol: 0.8283 g/mL = 828.3 g n-undecanal/L n-octanol at 20 °C.

Partition coefficient n-octanol / water (Pow) calculated from individual solubilities: Pow = 69025

log Kow (n-undecanal) = log (solub_n-octanol / solub_water) = log(69025) = 4.84

Description of key information

Partition coefficient n-octanol - water (OECD 117; EU-method A.8; WoE AQURA (2010), Givaudan (2010), Clariant, (2010)): Log Pow 4.8 (20°C)

Key value for chemical safety assessment

Log Kow (Log Pow):

4.8

at the temperature of:

20 °C

Additional information

Three reliable data sources are available for partition coefficient octanol-water. In absence of any indications in favour of any of these studies, a weight of evidence approach considering the peculiarities of the applied methods is deemed to be most appropriate.

Two reliable GLP studies (RL 1) are available applying the HPLC-method for determination of log Kow:

Both studies were performed according to OECD guideline for testing of chemicals No. 117 as well as EU method A.8. A sufficient number of reference compounds (7 for Givaudan study, 6 for AQURA study) were used, covering a log Kow-range well below and above the value found for submission substance n-undecanal, such that no extrapolation was performed. Further, both studies performed duplicate analyses for reference compounds as well as for the test item and deviation between both runs was marginal. Linear regression analysis resulted in high correlation coefficients well above 0.9, such that all requirements according to OECD 117 were fulfilled.

1) Result of Givaudan (2010) study:

Partition coefficient n-octanol / water of n-undecanal:

log Pow = 4.4 (n=2: 4.374; 4.375)

2) Result of AQURA (2010) study:

log Pow = 5.1 (n=2; 5.10; 5.10)

Concluding, two reliable GLP studies applying the same methodology received at log Pow values differing by 0.70 log units. This may well be due to different mobile phases used, different reversed phase columns applied (C18 versus C8) as well as completely different sets of reference compounds used. According to OECD 117, paragraph 13, log Pow values can be obtained within +/- 0.5 log units of those found with the shake flask method. As such, the difference in results obtained from both studies of 0.70 log units is still within the range of experimental variability.

Due to the results obtained for surface tension for n-undecanal,

Kow was determined in addition from individual solubilities in n-octanol and water according to EU method A.8

The surface tension of aqueous solutions of the test item n-undecanal was determined compliant with GLP according to OECD guideline no. 115 and EU test method A.5 with the ring method.

Surface tension (at 20°C) of the aqueous solution: 44.8 mN/m (see IUCLID section 4.10).

As such, based on the considerably lower surface tension of the solution of test item in water compared to pure water (72.75 mN/m) the test item would be considered to be surface active.

However, n-undecanal is not a surfactant; rather, reduction of surface tension of aqueous solutions is a phenomenon often observed for organic solvents in general, probably caused by the solvent interfering with hydrogen bonding of water.

According to EU Method A.8, the shake flask method is not applicable to surface active materials, and neither is the HPLC method.  For those compounds A.8 advises to rather estimate Kow from calculation based on the individual solubilities in n-octanol and water according to annex 1 of A.8.

Because of the result from the surface tension study mentioned above, for comparison and confirmation that available results according to OECD 117 (determination of Kow using the HPLC method) are valid, the ratio of solubilities in n-octanol and in water is used as the best estimate of the partition coefficient n-octanol water according to EU method A.8.

Solubility of n-undecanal in n-octanol was determined in a reliable study according to Product Properties Test Guidelines OPPTS 830.6319 - Miscibility (EPA). n-Undecanal was found to be fully miscible in n-octanol (Clariant, 2010). Concluding, solubility in n-octanol equals the density of n-undecanal:

Solubility in water of n-undecanal was determined in the reliable GLP compliant key study on water solubility (AQURA, 2010; OECD 105, flask method) to be 12 mg/L at 20 °C;

Solubility of n-undecanal in n-octanol: 0.8283 g/mL = 828.3 g n-undecanal/L n-octanol at 20 °C.

Partition coefficient n-octanol / water (Pow) calculated from individual solubilities: Pow = 69025

log Kow (n-undecanal) = log (solub_n-octanol / solub_water) = log(69025) = 4.84

Overall conclusion (weight of evidence) on log Kow of n-undecanal based on three reliable experimental determinations

The log Kow value obtained from individual solubilities in water and n-octanol of 4.84 is well within the range of values obtained from both of the OECD 117 studies (HPLC method; log Kow 4.4 and 5.1). This corroborates applicability of the HPLC method for this compound as well as the notion that n-undecanal is not a surface active compound in the sense of surfactants characterized by formation of micellar aggregates. As a conclusion, results from both of the reliable OECD 117 studies are valid and the method applicable for the test item n-undecanal.

Further, the value obtained from individual solubilities in water and n-octanol of log Kow 4.84 nearly exactly equals the mean value of the results obtained from application of the HPLC method for determination of log Pow:

Arithmetic mean value (from delogarithmized values): log Kow 4.88;

Geometric mean value (as the arithmetic mean of of log values): log Kow 4.75.

Taking all this into consideration, a log Kow value of 4.8 must be regarded to appropriately reflect available experimental results on log Kow and comes closest to the truth.

Overall result (WoE):

log Kow n-undecanal = 4.8