5,5'-dithiodi-1,3,4-thiadiazole-2(3H)-thione

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

June 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: estimation method (solubility ratio)

Qualifier:

no guideline followed

Principles of method if other than guideline:

As the specified test methods (shake flask and HPLC) detailed in EC Method A8 failed, the log Pow has been determine based on the ratio of the n-octanol solubiliy / water solubility.

Feasibility work performed during HPLC method development indicated that the test item was unretained on the column under standard conditions. This indicates that the HPLC method is not suitable for assessment of partition coefficient for the test item.
Feasibility work performed for the shake flask methodology indicated that it was not possible to prepare test item solutions in pre-saturated solvent at the required concentrations to perform the test. This indicates that the shake flask method is not suitable for assessment of partition coefficient for the specific test item hence the Log P was estimated based on the water and n-octanol solubility data.

GLP compliance:

yes

Type of method:

estimation method (solubility ratio)

Remarks:

Log P was estimated based on the water and n-octanol solubility ratio

Partition coefficient type:

octanol-water

Key result

Type:

log Pow

Partition coefficient:

1.46

Temp.:

25 °C

Remarks on result:

other: Mean log P

Details on results:

Log P was determined for each test condition as the log10 (mean n-octanol solubility / water solubility), where the water solubility was 167 mg/L.

The results show that solubility in n-octanol is slightly higher following sonication compared to 4 hour- stirring and overnight stirring, which were comparable. Differences between loading rates (1% and 2%) and between replicates were negligible.Therefore different Log P values were obtained from the different test conditions but the difference in values is not thought to be significant. With consideration of the observed behaviour of the test item in solution suggesting variation in solubility with time, the mean n-octanol solubility has been used to estimate the Log P value to be reported.

n-Octanol Solubility and Partition Coefficient Results

Test solution (Replicate)	Absorbance	Lambda max	Test Item Concentration (mg/L)^a	Solubility in n-Octanol (mg/L in filtrate)^b	Mean solubility in n-Octanol (mg/L in filtrate)	Partition Coefficient (log P)
n-Octanol Blank	No peaks detected		N/A	N/A	N/A	N/A
Overnight    stirring 1% (1)	0.885	340.0	18.09	4523	4541	1.43
Overnight   stirring 1% (2)	0.892	339.9	18.23	4558
Overnight   stirring 2% (1)	0.908	339.8	18.56	4640	4650	1.44
Overnight   stirring 2% (2)	0.912	339.9	18.64	4660
4hr stirring 1% (1)	0.876	340.6	17.90	4475	4473	1.43
4hr stirring 1% (2)	0.875	340.5	17.88	4470
4hr stirring 2% (1)	0.870	340.7	17.78	4445	4463	1.43
4hr stirring 2% (2)	0.877	340.7	17.92	4480
Sonication 1% (1)	1.062	340.0	21.71	5428	5369	1.51
Sonication 1% (2)	1.039	340.2	21.24	5310
Sonication 2% (1)	1.068	340.3	21.83	5458	5436	1.51
Sonication 2% (2)	1.059	340.1	21.65	5413
					Mean Log P:	1.46

a: Determined from calibration curve (linearity)

b: calcutaed as mg/l of test item x 100 / 0.04 (dilution in DMSO)

Conclusions:

The partition coefficient (log10 Pow) of the test item is estimated based on the ratio of n-octanol solubility and water solubility to be 1.46 at 25.0 +/- 1°C.

Key value for chemical safety assessment

Log Kow (Log Pow):

1.46

at the temperature of:

25 °C

Additional information

Key Study:

In a study conducted according to GLP, the partition coefficient (log Pow) of 5,5'-Dithiodi-1,3,4-thiadiazole-2(3H)-thione estimated based on the ratio of n-octanol solubility and water solubility is 1.46 at 25 ± 1°C (Intertek Pharmaceutical Services Manchester, 2016).