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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:
23 June - 01 July 2017
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:
2004
Deviations:
yes
Remarks:
According to TG OECD 117, log Pow values between 0 and 6 can be determined. Based on results of preliminary test, log Pow values are below this range. Therefore, the log Pow values were extrapolated based on the data obtained in this study.
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient - Shake Flask Method)
Version / remarks:
Regulation (EC) No 440/2008
Deviations:
yes
Remarks:
According to TG OECD 117, log Pow values between 0 and 6 can be determined. Based on results of preliminary test, log Pow values are below this range. Therefore, the log Pow values were extrapolated based on the data obtained in this study.
Principles of method if other than guideline:
According to TG OECD 117, log Pow values between 0 and 6 can be determined. The ones determined for the two main test item components (p-Nitrobenzoic acid, compound with 2,2',2''-nitrilotriethanol (1:1)) are both below this range.
This was known from the non-GLP preliminary test. Therefore, the log Pow values for the two main test item components were extrapolated based on the data obtained in this study.
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:
-0.28
pH:
7
Remarks on result:
other: extrapolated value of p-Nitrobenzoic acid calculated as the mean of two determinations
Key result
Type:
log Pow
Partition coefficient:
<= -1.08
pH:
7
Remarks on result:
other: extrapolated value of 2,2’,2’’-Nitrilotriethanol calculated as the mean of two determinations
Details on results:
Calculation method:
Using the SMILES code, the log Pow values for the two main test item components were given as 1.89 for p-Nitrobenzoic acid and -1.00 for 2,2',2''-Nitrilotriethanol (exper. database match; Hansch C. et al., (1995); EPI Suite™ v4.11).

HPLC method:
The dead time was determined to be 1.45 min.

The log Pow value for the test item component n-Nitrobenzoic acid was extrapolated to be -0.28 (95% confidence limits: -0.43 to -0.13) in the single injection run and -0.29 (95% confidence limits: -0.44 to -0.14) in the mixed injection run.
The determinations are valid since the values of log POW derived from these two repeated measurements fall within ±0.1 log units.
The log POW value for the test item component 2,2’,2’’-Nitrilotriethanol was extrapolated as well. As its retention time was slightly shorter than the one for Thiourea, which was used as dead time marker, an extrapolation based on the regression data obtained by the injection of reference items was not possible. Instead, the log Pow of 2,2’,2’’-Nitrilotriethanol can be given as less than or equal to the one of Thiourea corresponding to <= -1.08 (exper. database match; Govers H. et al., (1986); EPI Suite v4.11).
Consequently, the extrapolated log Pow value of p-Nitrobenzoic acid calculated as the mean of both determinations, is -0.28 (95% confidence limits: -0.13 to -0.44) and the extrapolated log Pow of 2,2’,2’’-Nitrilotriethanol is <= -1.08, both at a pH of 7.0.

Regression for the determination of the log Pow value of p-Nitrobenzoic acid with the single injection run

Plot log Pow vs log k:

 coefficient of regression (r2)  0.995
 intercept  0.390
 slope  1.38
 log Pow  -0.28
 95% confidence interval for log Pow  -0.43 - -0.13

Regression for the determination of the log Pow value of p-Nitrobenzoic acid with the mixed injection run

Plot log POW vs log k:

 coefficient of regression (r2)  0.995
 intercept  0.391
 slope  1.38
 log POW  -0.29
 95% confidence interval for log POW  -0.44 - -0.14
Conclusions:
The HPLC method was applied for the determination of the log Pow of p-Nitrobenzoic acid, compound with 2,2',2''-nitrilotri-ethanol (1:1) (CAS no. 7394-38-9). The extrapolated log Pow value of p-Nitrobenzoic acid calculated as the mean of two determinations, is -0.28 (95% confidence limits: -0.13 to -0.44) and the extrapolated log Pow of 2,2’,2’’-Nitrilotriethanol is <= -1.08, both at a pH of 7.0.
Executive summary:

The log Pow values of the two main components of the test item “p-Nitrobenzoic acid, compound with 2,2',2''-nitrilotriethanol (1:1)” (CAS no. 7394-38-9) were determined according to TG OECD 117. These determinations are based upon a regression analysis of the log Pow values of reference items against their respective retention times as determined by HPLC analysis. The log Pow values were determined at the environmentally relevant pH of 7.0.

The following reference items were used: Caffeine, 4 -Acetylpyridine, Aniline, Acetophenone, Nitrobenzene, Anisole and Chlorobenzene. The dead time of the HPLC system was determined with Thiourea.

This set of reference items yielded a calibration with log Pow values ranging from -0.07 to 2.8 and retention times ranging from 2.20 min to 76.9 min. The dead time of the HPLC system was 1.45 min.

Two determinations of the log Pow value of the two main test item components were conducted: first, by injecting each reference item and the test item separately; secondly, by a mixed injection of all of them together. 

The log Pow value for the test item component n-Nitrobenzoic acid was extrapolated to be -0.28 (95% confidence limits: -0.13 to –0.43) in the single injection run and -0.29 (95% confidence limits: -0.14 to -0.44) in the mixed injection run.

These determinations are valid since the values of log Pow derived from these two repeated measurements fall within ±0.1 log units.

The log Pow value for the test item component 2,2’,2’’-Nitrilotriethanol was extrapolated as well. As its retention time was slightly shorter than the one for Thiourea, which was used as dead time marker, an extrapolation based on the regression data obtained by the injection of reference items was not possible. Instead, the log Pow of 2,2’,2’’-Nitrilotriethanol can be given as less than or equal to the one of Thiourea corresponding to <= -1.08 (exper. database match; Govers H. et al., (1986); EPI Suite v4.11).

Consequently, the extrapolated log POW value of p-Nitrobenzoic acid calculated as the mean of both determinations, is -0.28 (95% confidence limits: -0.13 to -0.44) and the extrapolated log POW of 2,2’,2’’-Nitrilotriethanol <= -1.08, both at a pH of 7.0.

Description of key information

The partition coefficient of p-Nitrobenzoic acid, compound with 2,2’,2”-nitrilotriethanol (1:1) was determined in a GLP study according to the HPLC method (Klimisch 1, Arcadis, 2017). The extrapolated log Pow value of p-Nitrobenzoic acid, calculated as the mean of two determinations, is -0.28 (95% confidence limits: -0.13 to -0.44) and the extrapolated log Pow of 2,2’,2’’-Nitrilotriethanol is <= -1.08, both at a pH of 7.0.

Key value for chemical safety assessment

Additional information

The log Pow value for constituent p-Nitrobenzoic acid is -0.28 at a pH of 7.0.

The log Pow value for constituent 2,2’,2’’-Nitrilotriethanol is <= -1.08 at a pH of 7.0.

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