Methylthiouracil

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Reliablity 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Deviations:

no

GLP compliance:

no

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

Name: 6-Methyl-2-Thiouracil
Batch No: 151117
Purity 98.46%
Manufactured date 15.11.2017
Expiry Date 14.11.2019

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

ca. -1.703

Temp.:

30 °C

pH:

ca. 6.2

Details on results:

The obtained retention times, capacity factors and corresponding log Pow values of reference substances are presented as Table 1, Table 2 and Table 3. The calibration graphs of each test are presented as Figures 1 to Figure 3. Correlation coefficients (r) of calibration graphs of Determination 1, Determination 2 and Determination 3 were 0.9867, 0.9866 and 0.9450, respectively. Under each determination, test item solutions were injected to HPLC in duplicate and the partition coefficient of test item were -1.85, -1.83 and -1.43 for Determination 1, Determination 2 and Determination 3, respectively (Table 4).
The obtained correlation coefficients of each test were in acceptable range, i.e., above 0.9. The variation among the values of partition coefficient obtained from Determination 1 and Determination 2 was well within the range of ± 0.1 log units, showing that repeatability of the method used was acceptable and the variation among Determination 1, Determination 2 and Determination 3 was
well within the range of ± 0.5 log units, showing that reproducibility of the method used was acceptable.
The partition coefficient of the test item, 6-methyl-2-thiouracil Technical was -1.80 (Table 4) and representative chromatograms are presented as Figure 4 to Figure 15.

TABLE 1.  Results of Determination 1

Reference substance / Chemical	Repli- cation	Retention time (min.)	Mean Retention time (min.)	Capacity factor (k)	log k	logPow^(1)
Thiourea (inert substance)	R1	2.413	2.407	-	-	-
	R2	2.400
Acetanilide	R1	3.027	3.027	0.26	-0.59	1.0
	R2	3.027
Aniline	R1	3.293	3.287	0.37	-0.43	0.9
	R2	3.280
Diphenyl amine	R1	5.680	5.687	1.36	0.13	3.4
	R2	5.693
Phenyl benzoate	R1	6.120	6.134	1.55	0.19	3.6
	R2	6.147
Diphenyl ether	R1	7.667	7.680	2.19	0.34	4.2
	R2	7.693
Biphenyl	R1	7.973	7.987	2.32	0.37	4.00
	R2	8.000
6-Methyl-2-Uracil (Test item)	R1	2.520	2.527	0.05	-1.3	-1.85
	R2	2.533

 

(1)  OECD Guideline No.:117 

(2)  Calculated

 

TABLE 2.  Results of Determination 2

Reference substance / Chemical	Replication	Retention time (min.)	Mean Retention time (min.)	Capacity factor (k)	log k	logPow^(1)
Thiourea (inert substance)	R1	2.400	2.400	-	-	-
	R2	2.400
Acetanilide	R1	3.027	3.027	0.26	-0.59	1.0
	R2	3.027
Aniline	R1	3.307	3.307	0.38	-0.42	0.9
	R2	3.307
Diphenyl amine	R1	5.800	5.800	1.42	0.15	3.4
	R2	5.800
Phenyl benzoate	R1	6.293	6.287	1.62	0.21	3.6
	R2	6.280
Diphenyl ether	R1	7.867	7.867	2.28	0.36	4.2
	R2	7.867
Biphenyl	R1	8.160	8.174	2.41	0.38	4.00
	R2	8.187
6-Methyl-2-Uracil (Test item)	R1	2.520	2.520	0.05	-1.30	-1.83
	R2	2.520

(3)  OECD Guideline No.:117 

(4)  Calculated

 

    

 

TABLE 3.  Results of Determination 3

Reference substance / Chemical	Replication	Retention time (min.)	Mean Retention time (min.)	Capacity factor (k)	log k	logPow^(1)
Thiourea (inert substance)	R1	2.400	2.400	-	-	-
	R2	2.400
Acetanilide	R1	3.040	3.040	0.27	-0.57	1.0
	R2	3.040
Phenacetin	R1	3.147	3.147	0.31	-0.51	1.6
	R2	3.147
Aniline	R1	3.307	3.307	0.38	-0.42	0.9
	R2	3.307
Methyl benzoate	R1	4.507	4.507	0.88	-0.06	2.1
	R2	4.507
Diphenyl amine	R1	5.853	5.867	1.44	0.16	3.4
	R2	5.880
Phenyl benzoate	R1	6.320	6.327	1.64	0.21	3.6
	R2	6.333
6-Methyl-2-Uracil (Test item)	R1	2.520	2.520	0.05	-1.30	-1.43
	R2	2.520

(1)  OECD Guideline No.:117 

(2)  https://pubchem.ncbi.nlm.nih.gov/compound/phenacetin

(3)  https://pubchem.ncbi.nlm.nih.gov/compound/benzo_a_pyrene

(4)  Calculated

 

TABLE 1.                                                             Partition Co-efficient (n-octanol/water) of 6-methyl-2-                                                                                        thiouracil Technical

Determination	log Pow	Repeatability*  (log units)	Reproducibility^@ (log units)
1	-1.85	-0.02	-0.42
2	-1.83
3	-1.43
Overall Mean ± s.d	-1.703 ± 0.24

 

Note:

*  Repeatability is the variation between Determination 1 and 2

     Repeatability = Log P_owof determination I - Log P_owof determination II

^@   Reproducibility is the variation between Determination 1 and 3 and    Determination 2 and 3

     Reproducibility = Log P_owof determination I - Log P_owof determination III

 

 Please find the below mentioned curve in attched report.

FIGURE 1.       Calibration Curve - Determination 1

FIGURE 2. Calibration Curve - Determination 2

FIGURE 3.       Calibration Curve - Determination 3

FIGURE 4.       RepresentativeChromatogramof Dead –Time    Analysis usingThiourea

FIGURE 5.       Representative Chromatogram of Reference SubstanceAcetanilide

FIGURE 6.       Representative Chromatogram of Reference SubstanceAniline

FIGURE 7.   Representative Chromatogram of Reference Substance Diphenyl amine 

  

FIGURE 8.       Representative­ Chromatogram ofReference SubstancePhenyl benzoate

FIGURE 9.       Representative Chromatogram of Reference SubstanceBiphenyl

FIGURE 10.   Representative Chromatogram ofTest Item

                       

                           

 

 

Conclusions:

The mean partition coefficient (Pow) of the test substance was found to be POW -1.703 ± 0.24 at 30 ºC.

Executive summary:

The mean partition coefficient (Pow) of the test substance was found to be  POW   -1.703 ± 0.24 at 30 ºC.

Key value for chemical safety assessment

Log Kow (Log Pow):

-1.703

at the temperature of:

30 °C