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Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24-10-2003 to 14-11-2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study performed under GLP. All relevant validity criteria were met.

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected: December 2002; signature: February 2003

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

2.98

Temp.:

40 °C

pH:

ca. 6.5

Remarks on result:

other: mean log Pow; (n=2)

HPLC method

The mean void time (t0) was determined to be 1.623 minutes.

The results of the HPLC method are given in the Table 3. The calibration curves of the log k’ of the reference substances as function of log Pow had a regression line represented by the equations:

Calibration: log k’ = 0.290 × log Pow + -0.530 (r = 0.996, n = 6)

 

Table 2. Calibration data

Standard	Retention Time (min)			Capacity Factor (k')	Log10 k'	Log10 Pow
	Injection 1	Injection 2	Mean
Thiourea	2.737	2.756	2.747	-	-	-
Benzene	6.113	6.112	6.113	1.23	0.0883	2.1
Toluene	8.184	8.181	8.183	1.98	0.297	2.7
Naphthalene	10.096	10.093	10.095	2.68	0.427	3.6
Phenanthrene	19.421	19.431	19.426	6.07	0.783	4.5
Triphenylamine	38.954	38.990	38.972	13.2	1.12	5.7
DDT	55.366	55.419	55.393	19.2	1.28	6.2

 

Table 3. Test item determination

Peak	Injection	Retention Time (min)	Capacity Factor (k')	Log10 k'	Log10 Pow	Mean Log10 Pow
1	1	8.640	2.15	0.332	2.98	2.98
	2	8.649	2.15	0.332	2.98

Overall log10 Pow: 2.98

Conclusions:

The partition coefficient of the test item was determined to be log Pow = 2.98 at 40°C and ca. pH 6.5

Executive summary:

The n-octanol/water partition coefficient was determined using the HPLC method within OECD TG 117 and EU Method A.8 in accordance with GLP. The test was performed with a concentration of 10.27 g test item/L injected at 5 µL with a mobile phase of 70% methanol : 30% HPLC water. Samples of the test item were analysed via HPLC on a C18 column with variable wavelength detector. Calibration was performed using six reference items with known log POW values (given by the guidelines). The dead time of the HPLC system was determined with thiourea. The dead time and the reference items were measured in duplicate. The test item was injected and measured in duplicate. Three individual partition coefficient values for each of the three chromatographic resolved test item signals were derived. A mean value was calculated from these individual log Pow values which were determined to be 3.10, 3.36 and 3.40 respectively. The partition coefficient of the test item was determined to be in the log Pow range: 3.10 to 3.40 at a mean temperature 30°C and approximately neutral pH.

Description of key information

log Pow = 2.98 at 40 °C and pH 6.5, OECD TG 117 - HPLC Method, 2003

Key value for chemical safety assessment

Log Kow (Log Pow):

2.98

at the temperature of:

40 °C

Additional information

Key study : OECD TG 117, 2003 : The n-octanol/water partition coefficient was determined using the HPLC method within OECD TG 117 and EU Method A.8 in accordance with GLP. The test was performed with a mobile phase of 75% methanol : 25% HPLC water. Samples of the test item were analysed via HPLC on a ODS/C18 column with variable wavelength detector. Calibration was performed using six reference items with known log POW values (given by the guidelines). The dead time of the HPLC system was determined with thiourea. The dead time and the reference items were measured in duplicate. The test item was injected and measured in duplicate. One individual partition coefficient value for the chromatographic resolved test item signal was derived. A mean value was calculated from these individual log Pow values which were determined to be 2.98. The partition coefficient of the test item was determined to be log Pow : 2.98 at a mean temperature 40°C and pH 6.5.