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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:

17 to 30 November 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

No further details in study report

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

>= 3.58 - <= 6.11

Temp.:

30.3 °C

pH:

5

Details on results:

See any other information on results

 

1.1.                   Reference items

1.1.1.      Retention times

The retention times of the reference items are presented in the table below:

Compound	tR 1 (min)	tR 2 (min)	ΔtR (min)	tR mean (min)	Δ tR / tR mean	Equilibrium? (<2%)
methylbenzoate	5.74	5.63	0.11	5.69	1.93%	YES
ethylbenzoate	6.95	6.84	0.11	6.90	1.59%	YES
ethylbenzene	10.02	9.90	0.12	9.96	1.20%	YES
cumene	12.48	12.37	0.11	12.43	0.88%	YES
butylbenzene	19.68	19.58	0.10	19.63	0.51%	YES
triphenylamine	35.68	35.63	0.05	35.66	0.14%	YES
DDT	47.45	47.38	0.07	47.42	0.15%	YES

with        t_R: retention time;

Δt_R: absolute value of the retention times difference.

The retention times observed for the peak of formamide, used for the determination of the dead time, was 3.22 in the first injection of the mix and 3.15 in the second injection.

 

1.1.                   Test item

1.1.1.      Retention times

A typical chromatogram of the test item is constituted of several peaks. The table below presents the retention times of the peaks at the beginning and at the end of the test item elution and the peaks that contribute an area of 5% or more of the total peaks :

	Relative area %Area				tR (min)				RSD
	#1	#2	#3	Mean	#1	#2	#3	Mean
Dead time t0	-	-	-	-	3.17	3.12	3.12	3.14	0.9%
First peak	0.1%	0.1%	0.1%	0.1%	10.72	10.67	10.73	10.71	0.3%
Peak 1	6.1%	8.3%	8.1%	7.5%	25.29	25.24	25.29	25.27	0.1%
Peak 2	5.6%	4.9%	5.1%	5.2%	32.71	32.80	32.76	32.76	0.1%
Peak 3	25.2%	25.7%	24.7%	25.2%	35.71	35.68	35.71	35.70	0.0%
Peak 4	9.9%	8.3%	8.1%	8.8%	36.24	36.26	36.30	36.27	0.1%
Peak 5	7.0%	7.2%	7.5%	7.2%	39.71	39.78	39.68	39.72	0.1%
Last peak	32.9%	32.4%	31.4%	32.2%	42.65	42.64	42.64	42.64	0.0%

RSD: Relative Standard Deviation

 

Calculation of k, log k, and log P_OW

The calculated capacity factors, k, for the 3 injections of the test item, their logarithms, log k, and the calculated log P_OW for each peak are presented in the table below. log P_OW is calculated using the regression equation obtained from the reference items:

log P_OW = (log k + 0.6339) / 0.2837

	k			log k			log POW
	#1	#2	#3	#1	#2	#3	#1	#2	#3
First peak	2.38	2.42	2.44	0.38	0.38	0.39	3.57	3.57	3.61
Peak 1	6.98	7.09	7.11	0.84	0.85	0.85	5.20	5.23	5.23
Peak 2	9.32	9.51	9.50	0.97	0.98	0.98	5.65	5.69	5.69
Peak 3	10.26	10.44	10.45	1.01	1.02	1.02	5.79	5.83	5.83
Peak 4	10.43	10.62	10.63	1.02	1.03	1.03	5.83	5.86	5.86
Peak 5	11.53	11.75	11.72	1.06	1.07	1.07	5.97	6.01	6.01
Last peak	12.45	12.67	12.67	1.10	1.10	1.10	6.11	6.11	6.11

The following table presents the relative area of each peak, their mean log P_OW and the associated standard deviation:

	%Area	log POW mean	Standard deviation
First peak	0.1%	3.58	0.023
Peak 1	7.5%	5.22	0.017
Peak 2	5.2%	5.68	0.023
Peak 3	25.2%	5.82	0.023
Peak 4	8.8%	5.85	0.017
Peak 5	7.2%	6.00	0.023
Last peak	32.2%	6.11	0.000

 

Conclusions:

Using the HPLC method, a partition coefficient between 3.58 and 6.11 was determined for the test item. The partition coefficients determined for the peaks at the beginning and at the end of the test item elution and the peaks that contribute an area of 5% or more of the total peaks area are (see any other information on results) These values are the mean of three independent measurements.

Executive summary:

Determination of the Partition Coefficient n-octanol/water (log POW) of RED HF2.
Introduction
A study was performed to assess the partition coefficient of the test item by the HPLC method. The method followed was designed to be compliant with the OECD Guideline for Testing of Chemicals No. 117, “Partition Coefficient (n-octanol/water): HPLC Method” (30 June 2022).
Methods
This study was performed using the HPLC method. Seven reference items with different retention times were used to produce the calibration curve. They were chosen in relation with the expected retention time of the test item. For each reference item, two determinations were performed. The capacity factor k was calculated from the retention time of formamide (dead time) and the retention time of the respective reference item. A calibration function (log k versus log POW, linear fit) was determined based on literature values of log POW for the reference items.
Results
Using the HPLC method, a partition coefficient between 3.58 and 6.11 was determined for the test item. The partition coefficients determined for the peaks at the beginning and at the end of the test item elution and the peaks that contribute an area of 5% or more of the total peaks area are:

 

	%Area	log POW
First peak	0.1%	3.58
Peak 1	7.5%	5.22
Peak 2	5.2%	5.68
Peak 3	25.2%	5.82
Peak 4	8.8%	5.85
Peak 5	7.2%	6.00
Last peak	32.2%	6.11

 

These values are the mean of three independent measurements.

Description of key information

Using the HPLC method, a partition coefficient between 3.58 and 6.11 was determined for the test item.

Key value for chemical safety assessment

Log Kow (Log Pow):

6.11

at the temperature of:

30.3 °C