2-hydroxy-1-[4-[4-(2-hydroxy-2-methylpropanoyl)phenoxy]phenyl]-2-methylpropan-1-one

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2019-01-07 - 2019-01-09 (experimental phase)

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

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

and Method A.24 (Regulation EC No. 2016/266)

Deviations:

no

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:

2.39

Temp.:

20 °C

pH:

7

Preliminary Tests

The preliminary test at room temperature showed, that the octanol solubility of the test item was between 16.6 and 166 g/L. The observations of the preliminary test are summarized in Table 1 below:

Table 1: Preliminary test for the octanol solubility

Amount of test item [g]	Total volume of added octanol [mL]	Stirring time at RT [min]	Remark
0.26	10	45	dissolved
0.83	10	1110	not dissolved

With the water solubility of < 10 mg/L, estimated in the preliminary test of study no. CSL-18-1435.03, and the solubility in octanol between 26 and 83 g/L, determined from this preliminary test, the partition coefficient is estimated to be between 3.4 and 3.9.

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 (see 'Attached backgrund material', Figure 2 and Figure 3).

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 2 below shows the measurements of the dead time marker.

Table 2: Retention time of the dead time marker

	1^strun	2^ndrun	mean value
t0(min)	2.590	2.588	2.589

Table 3 shows the results of the first measurement series of the reference items.

Table 3: Retention times of the reference items (1^stmeasurement)

reference item	tR	k	log k	log POW [1]
Acetanilide	3.273	0.264	-0.578	1.0
4-Methyl benzyl alcohol	3.605	0.392	-0.406	1.6
Cinnamyl alcohol	3.660	0.414	-0.383	1.9
Allyl phenyl ether	6.103	1.357	0.133	2.9
Diphenyl ether	8.505	2.285	0.359	4.2
Fluoranthene	15.094	4.830	0.684	5.1
4,4’-DDT	23.341	8.015	0.904	6.5

[1] Literature values of log P_OW from OECD Test Guideline 117 (2004)

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

log P_OW = 3.461 x log  k + 2.962

correlation coefficient r = 0.9884

Table 4 shows the results of the second measurement series of the reference items.

Table 4: Retention times of the reference items (2^ndmeasurement)

reference item	tR	k	log k	log POW^[1]
Acetanilide	3.272	0.264	-0.579	1.0
4-Methyl benzyl alcohol	3.606	0.393	-0.406	1.6
Cinnamyl alcohol	3.658	0.413	-0.384	1.9
Allyl phenyl ether	6.103	1.357	0.133	2.9
Diphenyl ether	8.501	2.284	0.359	4.2
Fluoranthene	15.092	4.829	0.684	5.1
4,4’-DDT	23.343	8.016	0.904	6.5

[1] Literature values of log P_OWfrom OECD Test Guideline 117 (2004)

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

log P_OW= 3.460 x log  k + 2.963

correlation coefficient r = 0.9884

With the determined regression coefficients a and b, the log P_OW of the test item can be calculated for both measurements. The HPLC chromatogram of the test item is shown in Figure 1 (see 'Attached background material', Figure 1)

Table 5 shows the measured retention times of the test item and the calculated log P_OW values for both measurement series.

Table 5: Retention times of the test item

test item	tR	k	log k	log POW	POW
1^stmeasurement	4.365	0.686	-0.164	2.40	249
2^ndmeasurement	4.361	0.684	-0.165	2.39	247
mean value				2.39	248
standard deviation				< 0.01	1.0

Conclusions:

partition coefficient at 20 °C: log Pow 2.39 ± < 0.01

Executive summary:

The partition coefficient at 20 °C of the test item 2-Hydroxy-1-[4-(4-(2-hydroxy-2-methylpropionyl)phenoxy)phenyl]-2-methylpropan-1-one was determined by means of the HPLC method, according to regulation EC No. 440/2008 method A.8., Regulation EC No. 2016/266 method A.24., and OECD Test Guideline 117 (2004) to be: log P_OW = 2.39 ± < 0.01

Description of key information

The partition coefficient of the test substance was determined using an estimation method involving the solubility in n-octanol and in water according to OECD Guideline 117 and EU Method A.8 (Schiewer, 2019). 

Supporting modelling was conducted using the KOWWIN v1.68 model of EPIWIN v4.1. The modelled log Koc was 2.63. The prediction falls within the applicability domain of this model. 

Key value for chemical safety assessment

Log Kow (Log Pow):

2.39

at the temperature of:

20 °C

Additional information

The estimation method results were retained as key data.