Monophosphothiamine

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10 Jan - 27 Jan 2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Partition coefficient of the test item was calculated based in the ratio of its water solubility and its octanol solubility (based on OECD 105).

Qualifier:

according to guideline

Guideline:

other: OECD 105 (Flask Method for Determination of octanol solubility)

Version / remarks:

adopted in 2008

GLP compliance:

no

Type of method:

calculation method (fragments)

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

Storage conditions: Ambient temperature (10 to 30 °C), dry

Analytical method:

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

-4.7

Temp.:

20 °C

Remarks on result:

other: pH not measured

Results
Table 1 – Preliminary visual estimation of n-octanol solubility

Amount of test item [mg]	Added volume of n-octanol [mL]	Total volume of n-octanol [mL]	Stirring time [h]	Appearance of mixture
26.6	2	2	~ 0.7	Not dissolved
	8	10	~ 0.8
	90	100	~ 18

 

The solubility of the test item in n-octanol was: c_s^n-octanol< 266 mg/L (without correction for the purity).

Calculation of Partition Coefficient from Preliminary Test
The calculation was done with the result of the preliminary estimation of water solubility determined in the study report of reference 4.8 -1, i.e. c_s^water> 95.3 g/L and the c_s^n-octanolvalue above. It was calculated to be: log P_OW< -2.6.

The calculated value obtained from KOWWIN (part of EPI Suite) was log P_OW= -4.9.

Due to the calculations, the partition coefficient was estimated based on the ratio of the solubilities in water and octanol.

Determination of solubility in n-octanol – Flask Method
The n-octanol solubility was calculated from the measured and unrounded concentration values (not from the rounded values given in table 2).

Table 2 – n-octanol Solubility Experiments of the Test Item

Experiment	24 h experiment	48 h experiment	72 h experiment	Blank experiment (72 h)
Test item amount [mg]	66.8	67.7	67.2	--
Octanol amount [mL]	50
Stirring time at 30 °C [h]	24	48	72	72
Dilution factor	25
Measured concentration [mg/L]	0.123/0.138	0.152/0.143	0.144/0.145	--/--
Mean concentration [mg/L]	0.130	0.148	0.144	--
n-octanol solubility [g/L]	0.0033	0.0037	0.0036	--

 

The n-octanol solubility of the test item at 20 °C was determined to be 0.0035 g/L.

Calculation of Partition Coefficient from Individual Solubilities
In the study report in reference 4.8 -1, the water solubility of the test item at 20 °C was c_s^water= 176 g/L (± 2 g/L). Thus, the partition coefficient was calculated to be:

log P_OW= -4.7

 

Description of key information

log P_OW = -4.7 at 20 °C (EU Method A.8., Calculation method)

Key value for chemical safety assessment

Log Kow (Log Pow):

-4.7

at the temperature of:

20 °C

Additional information

Partition coefficient was determined based on the ratio of the individual solubilities of the test item in water and octanol. The individual octanol solubility was determined using the flask method (OECD 105).