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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Between 17 February and 30 March 2012.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions.
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Deviations:
no
GLP compliance:
yes
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
4.11
Temp.:
30 °C
pH:
7.1
Details on results:
Results
Preliminary estimate
The estimated log10 Pow was calculated to be 3.35.

Definitive test
Please see Attachment 3 for Typical Chromatography.

Calibration

The retention times of the deadtime and the retention times, capacity factors (k') and log10Powvalues for the reference standards are shown in the following tables:

 

Table 3.2

 

Dead Time

Retention Time (mins)

Mean Retention Time (mins)

Injection 1

Injection 2

Thiourea

1.429

1.433

1.431

 

Table 3.3

 

Standard

Retention Time (mins)

Mean Retention Time (mins)

Capacity Factor (k')

Log10k'

Log10Pow

Injection 1

Injection 2

2-Butanone

1.701

1.706

1.704

0.190

-0.720

0.3

Benzene

3.154

3.163

3.159

1.21

8.18 x 10-2

2.1

Toluene

4.383

4.393

4.388

2.07

0.315

2.7

Naphthalene

5.510

5.530

5.520

2.86

0.456

3.6

Phenanthrene

11.244

11.268

11.256

6.87

0.837

4.5

Triphenylamine

26.482

26.526

26.504

17.5

1.24

5.7

Partition coefficient of sample

The retention times, capacity factor and log10Powvalue determined for the sample are shown in the following table:

 

Table 3.4

 

Injection

Retention Time (mins)

Capacity Factor (k)

Log10k'

Log10Pow

1

8.767

5.13

0.710

4.12

2

8.717

5.09

0.707

4.11

 

Mean log10Pow:          4.11
Partition coefficient:  1.30 x 104

 

 

  

Discussion

The HPLC method had been originally attempted using ultra-violet (UV) detection (210 and 240 nm) but no significant peaks for the main components of the test item were detected, even at high concentration. The peaks that were detected did not appear too correlated with the main components and therefore were probably highly UV adsorbing impurities. This lead to the shake-flask method being attempted (EC A8, OECD 107), but unsolved reoccurring problems with the analytical method resulted in the HPLC method being returned to. The shake-flask method results, although subject to error because of the analytical issues, were in the range of log10Pow 3.0 to 3.7.

 

This second attempt employed the detection capabilities of an Evaporative Light Scattering Detector (ELSD) and proved to be very effective in detecting the main components of the test item but with minimal detection of the peaks seen with UV detection.

 

The peak in the sample chromatography at 10 minutes was approximately 3 % by percentage area normalization and had a log10Pow of 4.30.

 

Conclusions:
The partition coefficient of the test item has been determined to be 1.30 x 104, log10 Pow 4.11.
Executive summary:

Test System

The determination was carried out using the HPLC Method designed to be compatible with Method A8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 117 of the OECD Guidelines for Testing of Chemicals, 13 April 2004.

Principle of the Test

The partition coefficient of the test item was determined from its elution time in comparison with recommended reference items using a reversed-phase column. Chemicals injected onto such a column move along by partitioning between the mobile phase, which is partly aqueous, and the hydrocarbon stationary phase. Elution time will depend of the hydrocarbon/water partition coefficient. Water-soluble chemicals will be eluted first and oil-soluble substances later.

 

Conclusion

The partition coefficient of the test item has been determined to be 1.30 x 104, log10Pow 4.11.

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
Experimental Start (OECD and EPA): October 19, 2005 Experimental Termination: October 20, 2005
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions.
Qualifier:
according to guideline
Guideline:
EPA OPPTS 830.7570 (Partition Coefficient, n-octanol / H2O, Estimation by Liquid Chromatography)
Deviations:
no
GLP compliance:
yes
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
>= -0.91 - <= 5.48
Remarks on result:
other: the weighted mean Log Kow for the test substance was determined to be 1.19.
Details on results:
Along with analysis of reference standards, a standard of thiourea was injected in duplicate (once near the beginning and once near the end of the HPLC sequence) to determine the analytical column dead time (t0) for use in calculating capacity factors (k′) of the reference standards and the test substance. The mean retention time of the duplicate thiourea standard injections was 1.674 minutes.

Six additional reference standards were analyzed with the test substance. The reference standard series was injected at the beginning and at the end of the HPLC sequence. The capacity factors of each standard were calculated based upon their retention times. Calculated Log k′ values for acetanilide, 2 -nitrophenol, toluene, naphthalene, phenanthrene, and DDT reference standards are presented in Table 3 (Attachment 5 of this Summary).

The reference standard calibration curve is presented in Figure 1 (Attachment 3 of this Summary). Typical reference standard
chromatograms are presented in Figures 2 through 8. (Attachment 6 of this Summary) The test substance was sequentially injected in triplicate. The test substance eluted as eight resolved peaks. The peak retention times for the test substance ranged from 1.796 ± 0.000577 minutes to 7.266 ± 0.0306 minutes. The capacity factors (k′) for the minimum and maximum retained the test substance components were then calculated based on the above retention time range. The corresponding mean partition coefficients (Log Kow) for the test substance were calculated to range from an extrapolated value of –0.91 to an 5.48. The calculated mean retention times, capacity factors, and mean partition coefficients for the test substance are presented in Table 4 (Attachment 7 of this Summary). A representative chromatogram of the test substance is presented in Figure 9 (Attachment 8 of this Summary).
Conclusions:
Under the chromatographic conditions specified in guidelines, the test substance eluted as eight resolved peaks. The corresponding partition coefficients (Log Kow) for the test substance were calculated as (-0.91), 2.06, 2.81, 3.81, 4.38, 4.50, 4.62 and 5.48. The values in parentheses were extrapolated. Using the measured peak area for each calculated partition coefficient, the weighted mean Log Kow for the test substance was determined to be 1.19.
Executive summary:

Introduction

Wildlife International, Ltd. determined the n-octanol/water partition coefficient of the test substance using the high performance liquid chromatography estimation method.

Methods

The study was conducted at the Wildlife International, Ltd. analytical chemistry facility in Easton, Maryland. The study was performed based on procedures in the Product Properties Test Guidelines, OPPTS 830.7570, Partition Coefficient (n-Octanol/Water), Estimation by Liquid Chromatography (1).

This method is based on procedures presented in the OECD Guideline for the Testing of Chemicals, 117: Partition Coefficient (n-octanol/water), High Performance Liquid Chromatography (HPLC) Method (2), TSCA Title 40 of the Code of Federal Regulations, Part 796, Section 1570: Partition Coefficient (n- Octanol/Water) – Estimation by Liquid Chromatography (3) and Council of the European Communities Directive 92/69/EEC Annex V, Method A.8 (5).

The n-octanol/water partition coefficient of the test substance was determined using high performance liquid chromatography (HPLC) with ultraviolet detection (UV). The study was identified as Project Number 264C-104. All raw data generated by Wildlife International, Ltd. and a copy of the final report are filed under Project Number 264C-104 in archives located on the Wildlife International, Ltd.site.

Conclusion

Under the chromatographic conditions specified in guidelines, the test substance eluted as eight resolved peaks. The corresponding partition coefficients (Log Kow) for the test substance were calculated as (- 0.91), 2.06, 2.81, 3.81, 4.38, 4.50, 4.62 and 5.48. The values in parentheses were extrapolated. Using the measured peak area for each calculated partition coefficient, the weighted mean Log Kow for the test substance was determined to be 1.19.

Description of key information

The Log Pow of the substance was determined to be 4.11; study performed in accordance with OECD 117; Fox (2012)

Key value for chemical safety assessment

Log Kow (Log Pow):
4.11
at the temperature of:
30 °C

Additional information

In a GLP compliant partition coefficient study conducted in accordance with standardised guidelines, the Log Pow of the test substance was determined using the HPLC method. Under the conditions of the test, the Log Pow of the substance was determined to be 4.11.