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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
Version / remarks:
The study is conducted in accordance with the following guidelines:
• OECD Guidelines for the Testing of Chemicals, Method No. 117, adopted 13. April 2004: “Partition Coefficient (n-octanol/water), High Performance Liquid Chromatog-raphy (HPLC) Method“
• Council Regulation (EC) No 440/2008 of 30. May 2008, published 31. May 2008, Method A.8 “Partition Coefficient“
• Commission Regulation (EU) 2016/266 of adopted 7 December 2015 amending Regu-lation EC No. 440/2008, Method A.24 “Partition Coefficient (N-OCTANOL/WATER), HIGH PERFORMANCELIQUID CHROMATOGRAPHY (HPLC) METHOD
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
< 0.3
Temp.:
20 °C
pH:
ca. 5.5
Key result
Type:
log Pow
Partition coefficient:
< 3.29
Temp.:
20 °C
pH:
ca. 5.5
Details on results:
The correlation log k/ log POW was used for the calculation of the log POW of the compo-nents of test item Blendazol Red Blendwell. Due to the fact that the retention time of peak 1 lay below the retention time of thiourea (log POW is not calculable) the log POW of this peaks is stated as < 0.3 (log POW of reference item with lowest retention time 2-Butanone is 0.3). The log POW of peak 2, 3 and 4 lay in the range of the reference items.
The log POW of Blendazol Red Blendwell is stated as < 0.3 – 3.29, determined at pH 5.5 therefore.  

1.1.1   Calculated Values

The calculated values are presented in the following table:

Table8.2‑c      Capacity Factor, log Capacity Factor, log POWof Test Item Peaks

Peak

Measurement No.

k

log k

log POW

1

1

-0.1649

n.c.*

n.c.*

2

-0.1648

n.c.*

n.c.*

3

-0.1731

n.c.*

n.c.*

Mean

 

 

n.c.*

Standard Deviation

 

 

n.c.*

2

1

0.8546

-0.0683

1.544

2

0.8486

-0.0713

1.537

3

0.8437

-0.0738

1.531

Mean

 

 

1.537

Standard Deviation

 

 

0.007

3

1

2.6044

0.4157

2.723

2

2.6002

0.4150

2.721

3

2.5851

0.4125

2.715

Mean

 

 

2.719

Standard Deviation

 

 

0.004

4

1

4.4788

0.6512

3.296

2

4.4569

0.6490

3.291

3

4.4281

0.6462

3.284

Mean

 

 

3.290

Standard Deviation

 

 

0.006

*Not calculable, because k is negative. The retention time of peak 1 is lower than the retention time of thiourea, which was used for the determination of the dead time of the method.

 

log POWwas calculated from the capacity factor as follows:

 

log POW= (log k + 0.7024) / 0.4107

Conclusions:

The test item chromatogram showed one large and three small peaks.
Although area is not necessarily correlated to absolute concentration if a UV detector is used, it is assumed that the test item consists mainly of peak 1 and of peak 4. As peaks 2 and 3 showed a relative area < 5 %, they were considered as minor peaks.
The correlation log k / log POW was used for the calculation of the log POW of the compo-nents of test item Blendazol Red Blendwell. Due to the fact that the retention time of peak 1 lay below the retention time of thiourea (log POW is not calculable) the log POW of this peak is stated as < 0.3 (log POW of reference item with lowest retention time 2-Butanone is 0.3). The log POW of peak 2, 3 and 4 lay in the range of the reference items.
The log POW of Blendazol Red Blendwell is stated as < 0.3 – 3.29 (mean), determined at pH 5.5 therefore.
Executive summary:

The partition coefficient was determined using the HPLC method according to the EU A.8 test guideline , The partition coefficient was determined in triplicate, at 20˚C and pH 5.5 obtaining a value (log Pow)

as < 0.3– 3.29 therefore

Description of key information

Summary -Results

Peak

Area
[mAU*min][1]

Relative Area [%]

Retention Time [min]

log POW
±Standard Deviation

1

5.6362

88.30

1.226

n.c.*

2

0.1923

3.01

2.722

1.537 ± 0.007

3

0.0468

0.73

5.295

2.719 ± 0.004

4

0.5081

7.96

8.030

3.290 ± 0.006


[1]mAU = milli absorbance units

Because the test item is ionisable, this study was conducted at pH 5.5 by usage of mobile phase, adjusted to pH 5.5.

Blendazol Red Blendwell is a salt and is charged 3 fold permanently. At pH range 4.5 – 6.5 Blendazol Red Blendwell is estimated to be charged 3fold mainly (≥ 90%). Therefore the determination was performed using mobile phase, adjusted to pH 5.5 to ensure a defined pH value.

The correlation log k/log POWis good: the coefficient of determination r2was calculated with 0.956. This value was considered as sufficiently high to use the calibration function for the determination of the log POW of the test itemBlendazol Red Blendwell.

The test item chromatogram showed one large and three small peaks.

Although area is not necessarily correlated to absolute concentration if a UV detector is used, it is assumed that the test item consists mainly of peak 1 and of peak 4. As peaks 2 and 3 showed a relative area < 5 %, they were considered as minor peaks.

Using the correlation log k / log POW, the log POWof three of four components of test itemBlendazol Red Blendwell was calculated:the log POWof peak 1 was not calculable, because its retention time lay below the retention time of thiourea. The reason for this lower retention time may be, that a charged molecule is repelled by unmodified silanole groups of the HPLC column material and elute for the dead time therefore.The log POWof this peak is stated as < 0.3 (log POWof reference item with lowest retention time 2-Butanone is 0.3)

As peaks 2 and 3 showed a relative area < 5 %, they were considered as minor peaks.

The log POWof Blendazol Red Blendwellis stated as < 0.3 and 3.29 therefore

Key value for chemical safety assessment

Log Kow (Log Pow):
0.3
at the temperature of:
25 °C

Additional information