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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:
2018
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)
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
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:
>= 0.3 - < 1.43
Temp.:
25 °C
pH:
>= 5 - <= 6

1.1.1   Calculated Values

The calculated values are presented in the following table:

Table9.2‑b     Capacity Factor, log Capacity Factor, logOW

Peak

Measurement No.

k

log k

log POW

1

1

-0.1083

n.c.*

n.c.*

2

-0.0968

n.c.*

n.c.*

3

-0.0968

n.c.*

n.c.*

Mean

 

n.c.*

n.c.*

Standard Deviation

 

n.c.*

n.c.*

2

1

0.1103

-0.9574

-0.744

2

0.0931

-1.0313

-0.917

3

0.0815

-1.0886

-1.050

Mean

 

 

-0.904

Standard Deviation

 

 

0.153

3

1

0.9444

-0.0248

1.431

2

0.9386

-0.0275

1.424

3

0.9386

-0.0275

1.424

Mean

 

 

1.426

Standard Deviation

 

 

0.004

4

1

1.7382

0.2401

2.048

2

1.7210

0.2358

2.038

3

1.7152

0.2343

2.035

Mean

 

 

2.041

Standard Deviation

 

 

0.007

5

1

3.5847

0.5545

2.782

2

3.5214

0.5467

2.764

3

3.4812

0.5417

2.752

Mean

 

 

2.766

Standard Deviation

 

 

0.015

*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 + 0.6382) / 0.4288

Conclusions:
Variations in the retention times of reference items and test item are very small. Therefore a stable configuration of the HPLC-column can be assumed.
The correlation log k/Log POW is acceptable: the coefficient of determination r2 was calcu-lated with 0.9616. This value was considered as sufficiently high to use the calibration function for the determination of the log POW of the test item Blendazol Orange Blendwell.
The log POW of peak 1 was not calculable, because the retention time lay below the retention time of thiourea. As the calculated log POW of peak 2 lay below the lowest log POW of the reference items (2-Butanone with log POW 0.3), the log POW of this peak is stat-ed as < 0.3. The log POW of peaks 3 to 5 lay in the range of the reference items.
The log POW of Blendazol Orange Blendwell is stated as < 0.3 – 2.77 (mean) therefore.
No observations were made which might cause doubts concerning the validity of the study outcome. The log POW of peaks 2 to 5 lay in the range of the reference items
Executive summary:

The partition coefficient was determined using the HPLC method according to the EU A.8 test guideline and using HPLC as the analytical method. The partition coefficient was determined in triplicate, at 25˚C obtaining a value (log Pow)

as < 0.3– 2.77 therefore.

Description of key information

The study was performed using a HPLC with a C18 column. Seven reference items with different retention times and thiourea for the determination of the dead time were used to produce a calibration curve, since retention time on hydrophobic columns and POWare correlated. The reference items were chosen on behalf of the pre-test.


One vial was filled with the reference item mix and one vial with the test item solution. The vials were analysed using the HPLC with the program described below. First one injection from the solvent blank methanol/water 65/35 (%v/v) was made. Then three injections were measured from the reference item mix, three injections from the test item and again three injections from the reference item mix.


For each reference item, the capacity factor K was calculated from the retention time of thiourea and the retention time of the respective reference item.

A calibration function (log K versus log POW, linear fit) was determined using the literature values for POWof the reference items and the retention times in the six determinations.

The test item solution in mobile phase showed a chromatogram with five peaks. Peak 4 and 5 showed a relative area > 5 % each.

With the calibration function log K versus log POW, the corresponding log POWvalues of the peaks were determined with:

 

Peak

Mean Area
[mAU*min][1]

Relative Area [%]

Mean Retention Time [min]

log POW
±Standard Deviation

1

13.3187

54.66

1.303

n.c.*

2

5.5644

22.69

1.586

-0.904**

3

4.4508

17.76

2.811

1.426

4

0.3604

1.48

3.947

2.041***

5

0.8365

3.42

6.561

2.766***

* 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
*** Minor peak with relative peak area < 5 %

 

 

These values are the means ± standard deviations of three independent determinations.

Using the correlation log k / log POW, the log POWof four components of the test itemBlendazol Orange Blendwell was calculated. The log POWof peak 1 was not calculable, because the retention time lay below the retention time of thiourea.As the calculatedlog POWof peak 2 lay below the lowestlog POWof the reference items (2-Butanone withlog POW0.3), thelog POWof peaks 1 and 2 is stated as < 0.3.The log POWof peaks 3 – 5 lay in the range of the reference items. Peaks 4 and 5 were considered as minor peaks with relative peak area < 5 %.

 

Thereforethelog POWofBlendazol Orange Blendwellis stated as

< 0.3– 1.43



[1]mAU = milli absorbance units

Key value for chemical safety assessment

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

Additional information

1.1     Test Item Blendazol Orange Blendwell

1.1.1   Measurement Data

The retention times of the test item are presented in the following table:

Table9.2‑a      Retention Times (RT) Test Item

Measurement

RT 1

RT 2

RT 3

RT 4

RT 5

 

min.

min.

min.

min.

min.

Measurement 1

1.292

1.609

2.817

3.967

6.642

Measurement 2

1.309

1.584

2.809

3.942

6.550

Measurement 3

1.309

1.567

2.809

3.934

6.492

Mean

1.303

1.586

2.811

3.947

6.561

Standard Deviation

0.010

0.021

0.005

0.017

0.076

 

1.1.1   Calculated Values

The calculated values are presented in the following table:

Table9.2‑b     Capacity Factor, log Capacity Factor, logOW

Peak

Measurement No.

k

log k

log POW

1

1

-0.1083

n.c.*

n.c.*

2

-0.0968

n.c.*

n.c.*

3

-0.0968

n.c.*

n.c.*

Mean

 

n.c.*

n.c.*

Standard Deviation

 

n.c.*

n.c.*

2

1

0.1103

-0.9574

-0.744

2

0.0931

-1.0313

-0.917

3

0.0815

-1.0886

-1.050

Mean

 

 

-0.904

Standard Deviation

 

 

0.153

3

1

0.9444

-0.0248

1.431

2

0.9386

-0.0275

1.424

3

0.9386

-0.0275

1.424

Mean

 

 

1.426

Standard Deviation

 

 

0.004

4

1

1.7382

0.2401

2.048

2

1.7210

0.2358

2.038

3

1.7152

0.2343

2.035

Mean

 

 

2.041

Standard Deviation

 

 

0.007

5

1

3.5847

0.5545

2.782

2

3.5214

0.5467

2.764

3

3.4812

0.5417

2.752

Mean

 

 

2.766

Standard Deviation

 

 

0.015

*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 + 0.6382) / 0.4288

 

1.1.1   Validity

The validity criteria and results are presented in the following table:

Table9.3‑a      Validity Criteria and Results

Peak

Parameter

Criterion

Found

Assessment

1

Range (Max – Min. log POW)

< 0.1

n.c.*

n.c.*

Value within Range of Reference Items

0.30 - 3.60

n.c.*

n.c.*

2

Range (Max – Min. log POW)

< 0.1

0.306

not valid

Value within Range of Reference Items

0.30 - 3.60

-0.904

not valid**

3

Range (Max – Min. log POW)

< 0.1

0.006

valid

Value within Range of Reference Items

0.30 - 3.60

1.426

valid

4

Range (Max – Min. log POW)

< 0.1

0.013

valid

Value within Range of Reference Items

0.30 - 3.60

2.041

valid

5

Range (Max – Min. log POW)

< 0.1

0.030

valid

Value within Range of Reference Items

0.30 - 3.60

2.766

valid

*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. As the retention time of peak 1 lies below the lowestretention timeof the reference items (2-Butanone withlog POW0.3), thelog POWof this peak is stated as < 0.3.

** As the calculatedlog POWof peak 2 lies below the lowestlog POWof the reference items (2-Butanone withlog POW0.3), thelog POWof this peak is stated as < 0.3.