2-naphthol

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17.05.2018 - 17.05.2018

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)

Version / remarks:

2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

no

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

>= 1.88 - <= 1.9

Temp.:

20 °C

pH:

8.3

Details on results:

Quality criteria  
The value of log Pow derived from repeated measurements made under identical conditions and using the same set of reference items should fall within a range of ± 0.1 log units.
Typically, the correlation coefficient r for the relationship between log k and log Pow for a set of test substances is around 0.9, corresponding to an octanol/water partition coefficient of log Pow ± 0.5 log units.

Preliminary Tests

The preliminary test at room temperature showed, that the octanol solubility of the test item was between 309.3 and 555.3 g/L.

Table: Preliminary test for the octanol solubility

Total amount of test item [g]	Total volume of added octanol [mL]	Stirring time at RT [min]	Remark
0.1247	20	35	dissolved
1.4176	10	85	dissolved
3.0931		4115	dissolved
5.5531		1345	not dissolved

With the estimated water solubility of the test item (0.1 – 1.1 g/L) and the estimated solubility in octanol (309.3 – 555.3 g/L) the partition coefficient log P_OW can be estimated to be between 2.7 and 3.5.

For the determination of the log P_OW at this value the HPLC method is recommended and carried out.

Main Test

After the measurements of the retention times t_R the log k values of the reference items were plotted as a function of their log P_OW values. The partition coefficient of the test item was obtained by interpolation of the calculated capacity factor on the calibration graph of the reference items.

Table: Retention time of the dead time marker

	1^strun	2^ndrun	mean value
t0(min)	1.615	1.616	1.616

 Table: Retention times of the reference items (1^stmeasurement)

reference item	tR	k	log k	log POW[1]
Acetanilide	2.012	0.245	-0.610	1.0
4-Methyl benzyl alcohol	2.145	0.328	-0.484	1.6
Cinnamyl alcohol	2.167	0.341	-0.467	1.9
Allyl phenyl ether	3.007	0.861	-0.065	2.9
Diphenyl ether	3.851	1.384	0.141	4.2
Fluoranthene	6.626	3.102	0.492	5.1

The first measurement and the linear regression of the calibration graph leads to an equation for the log P_OW.

Table: Retention times of the reference items (2^ndmeasurement)

reference item	tR	k	log k	log POW^1
Acetanilide	2.014	0.247	-0.608	1.0
4-Methyl benzyl alcohol	2.147	0.329	-0.483	1.6
Cinnamyl alcohol	2.169	0.343	-0.465	1.9
Allyl phenyl ether	3.007	0.861	-0.065	2.9
Diphenyl ether	3.852	1.384	0.141	4.2
Fluoranthene	6.630	3.104	0.492	5.1

 The second measurement and the linear regression of the calibration graph leads to an equation for the log P_OW. With the determined regression coefficients a and b, the log P_OW of the test item can be calculated for both measurements.

Table: Retention times of the test item

test item	tR	k	log k	log POW	POW
1^stmeasurement	2.247	0.391	-0.408	1.89	78.03
2^ndmeasurement	2.248	0.392	-0.407	1.89	77.54
mean value				1.89	77.78
standard deviation				< 0.01	0.35

 According to Regulation EC No. 440/2008 method A.8. and OECD Test Guideline 117 the test item has a partition coefficient at 20 °C of

log P_OW= 1.89 ± < 0.01

Conclusions:

The partition coefficient log P of 2-Naphthol was determined to be 1.89 at 20°C using the HPLC-method.

Executive summary:

The partition coefficient at 20 °C of the test item beta-Naphthol was determined by means of the HPLC method, according to Regulation EC No. 440/2008 method A.8. and OECD Test Guideline 117 (2004) to be:

log P_OW = 1.89 ± < 0.01

Description of key information

A study was performed to determine the partition coefficient of the test substance 2-naphthol using a HPLC method.  The study was performed in compliance with OECD Test Guideline 117 and Regulation EC No. 440/2008 method A.8.  It concluded that the partition coefficient log P of 2-naphthol at 20 ^oC was 1.89.

Key value for chemical safety assessment

Log Kow (Log Pow):

1.89

at the temperature of:

20 °C