Naphtha (Fischer-Tropsch), light, C4-10-branched and linear

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

April 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results.

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Deviations:

no

Principles of method if other than guideline:

In the absence of any dissociating groups, the test material being a mixture of alkanes, no manipulation of the mobile phase pH was necessary to ensure the molecular form of each component. Therefore the determination was performed at an approximately neutral pH.
By fraction collection and subsequent GC analysis, it was confirmed that all of the major components of the test material were successfully eluted during the isocratic period monitored.

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

gas chromatography

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

> 6.5

Temp.:

40 °C

pH:

ca. 7

Details on results:

- Mean log10Pow range: 4.40 to >6.50
- Partition coefficient: 2.51 x 10e4 to >3.16 x 10e6

Peaks from the test material eluted after the reference substances Naphthalene, Phenanthrene, Triphenylamine and DDT.
By percentage are normalisation, 60.2% of the test material had a log Pow-value greater than 6.50.

Calculation

1) Preliminary estimate

The preliminary estimate of the partition coefficient was calculated using the following equation:

P_OWestimate = solubility of the test material in n-octanol / solubility of the test material in water (Equation 1)

2) Capacity factor

The capacity factor was determined using the following equation:

k = (t_r-t₀)/t₀ (Equation 2)

where:

k = capacity factor

t_r= retention time (min)

t₀= dead time (min)

Results

1) Preliminary estimate

- approximate solubility in n-octanol: >54.3% (w/w)

- approximate solubility in water: <1.0 x 10^-3% (w/w)

- approximate P_ow: >5.43 x 10⁴

- log₁₀P_OW>4.74

2) Definitive test

a) Calibration

The retention times of thiourea and the retention times, capacity factors (k) and log₁₀P_OWvalues for the reference standards are shown in the following two tables:

Dead Time	Retention Time (min)		Mean Retention Time (min)
	Injection 1	Injection 2
Thiourea	1.902	1.909	1.906

Standard	Retention Time (mins)		Mean Retention Time (mins)	Capacity Factor (k)	Log10k	Log10Pow
	Injection 1	Injection 2
2-Butanone	2.203	2.203	2.203	0.156	-0.807	0.3
Benzene	3.144	3.145	3.145	0.650	-0.187	2.1
Toluene	3.776	3.780	3.778	0.983	-7.59 x 10^-3	2.7
Naphthalene	4.140	4.145	4.143	1.174	6.97 x 10^-2	3.6
Phenanthrene	5.753	5.763	5.758	2.022	0.306	4.5
Triphenylamine	11.662	11.714	11.688	5.134	0.710	5.7
DDT	16.672	16.733	16.703	7.765	0.890	6.5

A calibration curve was constructed from the retention time data of the thiourea and reference standard solutions. The capacity factors (k) for the reference standards were calculated using equation 2 (see above).

Logic P_OW-values of the reference standards are those quoted in Method 117 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

b) Partition coefficient of sample

The retention times, capacity factors and log₁₀P_OW-values determined for the sample are shown in the following table:

Peak Number	Injection	Retention Time (mins)	Capacity Factor (k)	Log10k	Logio Pow	Mean Log10Pow
1	1	6.114	2.209	0.344	4.41	4.40
	2	6.083	2.129	0.341	4.39
2	1	6.467	2.394	0.379	4.54	4.54
	2	6.467	2.394	0.379	4.54
3	1	6.659	2.495	0.397	4.61	4.61
	2	6.666	2.498	0.398	4.61
4	1	7.056	2.703	0.432	4.74	4.74
	2	7.067	2.709	0.433	4.74
5	1	8.536	3.480	0.542	5.15	5.16
	2	8.546	3.485	0.542	5.16
6	1	8.945	3.694	0.568	5.25	5.26
	2	8.959	3.702	0.568	5.26
7	1	11.546	5.059	0.704	5.77	5.77
	2	11.560	5.067	0.705	5.77
8	1	12.276	5.442	0.736	5.89	5.89
	2	12.301	5.456	0.737	5.90
9	1	14.934	6.837	0.835	6.27	6.26
	2	14.885	6.812	0.833	6.26
10	1	15.858	7.322	0.865	6.38	6.38
	2	15.891	7.340	0.866	6.38
11	1	17.085	7.966	0.901	>6.50	>6.50
	2	17.123	7.986	0.902	>6.50
12	1	20.549	9.784	0.991	>6.50	>6.50
	2	20.529	9.774	0.990	>6.50
13	1	21.977	10.533	1.023	>6.50	>6.50
	2	21.985	10.538	1.023	>6.50
14	1	23.986	11.588	1.064	>6.50	>6.50
	2	24.042	11.617	1.065	>6.50
15	1	28.661	14.041	1.147	>6.50	>6.50
	2	28.719	14.072	1.148	>6.50
16	1	30.848	15.189	1.182	>6.50	>6.50
	2	30.759	15.141	1.180	>6.50
17	1	33.732	16.702	1.223	>6.50	>6.50
	2	33.751	16.712	1.223	>6.50
18	1	40.043	20.014	1.301	>6.50	>6.50
	2	39.896	19.937	1.300	>6.50
19	1	43.172	21.657	1.336	>6.50	>6.50
	2	42.776	21.449	1.331	>6.50

The capacity factor was calculated using Equation 2 (see above) and the log₁₀P_OW-value determined with reference to the calibration curve.

The refractive index detector percentage area normalisation data is shown in the following table:

Peak number	Mean Percentage Area (%)
1	0.06
2	0.23
3	0.69
4	0.25
5	2.78
6	5.04
7	8.13
8	9.64
9	2.28
10	10.8
11	11.7
12	4.65
13	11.0
14	11.0
15	5.66
16	8.43
17	6.20
18	1.27
19	0.26

3) Summary

- Mean log₁₀P_OW range 4.40 to >6.50

- Partition coefficient range: 2.51 x 10⁴ to >3.16 x 10⁶

Conclusions:

partition coefficient: log10Pow = 4.40 to >6.50 at 40°C (by percentage area normalisation, 60.2% of the test material had a log Pow-value greater than 6.50)

Executive summary:

The partition coefficient of the test material was determined using the HPLC method (EU method A.8)

To allow detection of the test material, fractions of eluent were collected from the HPLC instrument for analysis by gas chromatography (GC).

The partition coefficient of the test material has been determined to be greater than 2.51 x 10⁴ to >3.16 x 10⁶, log₁₀P_OW 4.40 to >6.50 (arithmetic mean of two determinations at 40°C and pH 7). By percentage area normalisation, 60.2% of the test material had a log₁₀P_ow-value greater than 6.50.

Description of key information

partition coefficient of the test material: log10Pow = 4.40 to >6.50 at 40°C (by percentage area normalisation, 60.2% of the test material had a log Pow-value greater than 6.50)

Key value for chemical safety assessment

Log Kow (Log Pow):

6.5

at the temperature of:

40 °C

Additional information

The partition coefficient was determined according to EU Method A.8 (HPLC method).

To allow detection of the test material, fractions of eluent were collected from the HPLC instrument for analysis by gas chromatography (GC).

The partition coefficient of the test material has been determined to be greater than 2.51 x 10⁴to >3.16 x 10⁶, log₁₀P_ow 4.40 to >6.50 (arithmetic mean of two determinations at 40°C and pH 7). By percentage area normalisation, 60.2% of the test material had a log₁₀P_ow value greater than 6.50.

Partition coefficients for constituents of GTL Naphtha were calculated using KOWWIN v1.68 which was validated against measured data for relevant structures available in the public domain.