2,4-diethyl-9H-thioxanthen-9-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:

2017-05-11 - 2017-08-29

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)

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:

> 6.5

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
0.22	11	40	dissolved
0.83	5	30	not dissolved
	50	30	dissolved

With the water solubility of < 9.68 mg/L, determined in the preliminary test of the water solubility study, and the solubility in octanol of 16.6 to 166 g/L, determined from this preliminary test, the partition coefficient can be estimated to be between 3.2 and 4.2.

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)	1.700	1.700	1.700

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	2.031	0.195	-0.711	1.0
4-Methyl benzyl alcohol	2.163	0.272	-0.565	1.6
Cinnamyl alcohol	2.188	0.287	-0.542	1.9
Allyl phenyl ether	3.039	0.788	-0.104	2.9
Diphenyl ether	3.895	1.291	0.111	4.2
Fluoranthene	6.854	3.032	0.482	5.1
4,4’-DDT	8.313	3.890	0.590	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 = 3.810 x log  k + 3.716

correlation coefficient r = 0.9849

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	2.033	0.196	-0.708	1.0
4-Methyl benzyl alcohol	2.167	0.275	-0.561	1.6
Cinnamyl alcohol	2.190	0.288	-0.540	1.9
Allyl phenyl ether	3.040	0.788	-0.103	2.9
Diphenyl ether	3.894	1.291	0.111	4.2
Fluoranthene	6.855	3.032	0.482	5.1
4,4’-DDT	8.310	3.890	0.590	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= 3.820 x log  k + 3.713

correlation coefficient r = 0.9850

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	12.108	6.122	0.787	6.71	5182872
2^ndmeasurement	12.111	6.124	0.787	6.72	5241592
mean value				6.72	5212233
standard deviation				< 0.01	41521

Since the retention time of the test item was higher than the retention time of 4,4’-DDT and thus slightly outside the calibration, the partition coefficient can be given, according to EU-Method A.8. and OECD Test Guideline 117, as log P_OW > 6.5.

Conclusions:

- partition coefficient at 20 °C: log POW > 6.5 (the retention time of the test item was higher than the retention time of 4,4’-DDT and thus slightly outside the calibration)
- calculated log POW: 6.72 (arithmetic mean of two measurement series)

Executive summary:

The partition coefficient at 20 °C of the test item 2,4-Diethyl-9H-thioxanthen-9-one was determined by means of the HPLC method, according to EU-Method A.8. and OECD Test Guideline 117 to be: log P_OW > 6.5. The limit value of 6.5 is based on the retention time of the reference substance DDT. The mean calculated log P_OW was 6.72 (arithmetic mean of two measurement series).

Description of key information

partition coefficient at 20 °C (determined using HPLC method of EU Method A.8 / OECD 117; GLP): log POW > 6.5

Key value for chemical safety assessment

Log Kow (Log Pow):

6.5

at the temperature of:

20 °C

Additional information

The partition coefficient at 20 °C of the test item 2,4-Diethyl-9H-thioxanthen-9-one was determined by means of the HPLC method, according to EU-Method A.8. and OECD Test Guideline 117. The limit value of 6.5 is based on the retention time of the reference substance DDT. The mean calculated log P_OW was 6.72 (arithmetic mean of two measurement series).

A reliability score of 1 was assigned, in accordance with the criteria for assigning data quality in line with the principles described by Klimisch (1997).