Butanal, reaction products with aniline

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Radiolabelling:

no

Test temperature:

25°C

Details on study design: HPLC method:

Preparation of the test solutions.
The dead time marker sodium nitrate and the calibration substances were dissolved in acetonitrile / demineralized water 9:1 (v/v). The test item was dissolved in acetonitrile. The concentration for the calibration substances was approximately 0.02 to 0.05 mg/ml. The concentration for the test item was approximately 0.5 mg/ml.

Analytical monitoring:

yes

Details on test conditions:

The adsorption coefficient (K) is a partition coefficient and is defined as the ratio of the equilibrium concentrations of a dissolved substance in a two-phase system consisting of a sorbent (soil or sewage sludge) and an aqueous phase:
HPLC is performed on analytical columns packed with a commercially available cyano solid phase chemically bound onto silica. Chemicals injected onto such a column move along it by partitioning between the mobile solvent phase and the stationary cyano-phase. The chemicals are retained in proportion to their solid phase-water partition coefficient, with water-soluble chemicals eluted first and soil (sludge)-soluble chemicals last. This enables the relationship between the retention time on a cyano phase column and the soil(sludge/water adsorption coefficient to be established. The adsorption coefficient is deduced from the capacity factor (k), given by the expression where, tR is the retention time of the test item, and t0 is the dead-time, i.e. the average time a solvent molecule needs to pass the column. Quantitative analytical methods are not required; only the determination of retention times is necessary.
The HPLC method enables partition coefficients to be estimated in the log Koc range between 1.3 and 5. pH has a significant influence on sorption behaviour in particular for polar substances. For agricultural soils or tanks of sewage treatment plants pH normally varies between pH 5.5 and 7.5. For this reason the test is performed at pH 6 (adding citrate buffer to the mobile phase). In case more than 10 % of the test item is dissociated at pH 6, a second test has to be performed at a pH where test item is undissociated. The pKa value of Butanal, reaction products with aniline is:
3.19 ±0.38 for reaction product 1
3.48 ±0.70 for reaction product 2
3.93 ±0.50 for reaction product 3
4.79 ±0.50 for reaction product 4
3.76 ±0.50 for reaction product 5
2.69 ±0.50 for reaction product 6
(calculated with the software ACD/pKa v 7.0 at the structure of the test item). Therefore the non-ionized form of Butanal, reaction products with aniline exists at a pH value > 5.79 and the test can be carried out at pH 6.

Type:

log Koc

Value:

2.78

Temp.:

25 °C

Type:

log Koc

Value:

4.02

Temp.:

25 °C

Type:

log Koc

Value:

4.97

Temp.:

25 °C

Type:

log Koc

Value:

5.16

Temp.:

25 °C

Type:

log Koc

Value:

5.8

Temp.:

25 °C

Type:

log Koc

Value:

6.51

Temp.:

25 °C

Details on results (HPLC method):

Range of main peaks of the test item Butanal, reaction products with aniline determined by HPLC, RT = 3.2 - 5.8 minutes (Log Koc = 2.8 - 6.5)
Adsorption coefficient of main peaks of Butanal, reaction products with aniline determined by HPLC, calculated with area % and their corresponding Log Koc. (LogKoc = 4.9)

Statistics:

The log Koc value was calculated with the software PCKOCWIN v1.66 assuming the nonionic form. PCKOCWIN is owned by the U.S.Environmental Protection Agency.
Log Koc Prediction of six reaction products with aniline:
Result 1: log Koc = 3.64
Result 2: log Koc = 4.54
Result 3: log Koc = 5.36
Result 4: log Koc = 5.48
Result 5: log Koc = 5.36
Result 6: log Koc = 5.36

Partition coefficient of main peaks of the test item Butanal, reaction products with aniline determined by HPLC, calculated with area % and their correspondence Log Koc.

Retention time = min.	Area %	Log Koc	Log Koc (averange value of all peaks)
3.249	1.4499	2.78
3.845	21.5323	4.02
4.457	33.4399	4.97
4.603	30.7996	5.16
5.138	8.0649	5.80
5.837	4.5935	6.51
	Sum: 99.9		4.9

Validity criteria fulfilled:

yes

Remarks:

Five calibration standards with log Koc from 1.45 - 4.09 are established. Additionally a new reference substance was used in this test.

Conclusions:

The adsorption coefficient (Koc) of the test item was determined according to EU Method C.19 which is equivalent or similar to OECD Guideline 121.
The range of main peaks of the test item determined by HPLC (RT = 3.2 - 5.8 minutes) yielded a Log Koc = 2.8 - 6.5.
Adsorption coefficient of main peaks of Butanal, reaction products with aniline determined by HPLC, calculated with area % and their corresponding yielded a mean Log Koc of 4.9 (concentration-weighted mean value).

Executive summary:

The adsorption coefficient (Koc) of the test item was determined according to the HPLC method at 40 °C. In order to comply with the guideline OECD 121 and considering environmental relevance, pH 6 was chosen as pH value for the buffer. The reference Koc-values in the OECD-guideline presumably refer to 25 °C. Even though the column temperature was 40 °C, this temperature is without influence on the result of the determination. The calibration was done referring to Koc- values of reference substances determined at 25 °C. For the determination of the adsorption coefficient (Koc) five calibration standards with log Koc from 1.45 - 4.09 are established in the EG-test method. Additionally a new reference substance 9,10-Dimethyl-1,2-benzanthracene (7,12-Dimethylbenzanthracene) was used in this test. The experimental value of log Koc = 5.37 for 9,10-Dimethyl-1,2-benzanthracene was published by Donald A. Bahnick and William J. Doucette in the “Chemosphere, Vol. 17, No. 9, pp 1703-1715, 1988”. The chromatogram of the test item Butanal, reaction products with aniline showed a resolved band of 6 signals. 3 signals were eluted between 4.5 and 5.8 minutes. No calibration substance with a Koc–value above the value for these signals of the test item was available. For this reason the results for these signals were extrapolated. Although the determined value does not exactly meet the range of application of the test guideline (1.3 – 5), we consider the value as valid (measurement uncertainty +/- 0.5 log units). For adsorption coefficient of the test item Butanal, reaction products with aniline determined by HPLC follows:

Adsorption coefficient of main peaks of Butanal, reaction products with aniline determined by HPLC, calculated with area % and their corresponding Log Koc = 4.9.

The range of main peaks of the test item Butanal, reaction products with aniline determined by HPLC, RT = 3.2 - 5.8 minutes yielded a Log Koc = 2.8 - 6.5)

Adsorption coefficient of main peaks of Butanal, reaction products with aniline determined by HPLC, calculated with area % and their corresponding yielded a mean Log Koc of 4.9 (concentration-weighted mean value).

Description of key information

The adsorption coefficient (Koc) of the test item was determined according to EU Method C.19 which is equivalent or similar to OECD Guideline 121.
The range of main peaks of the test item determined by HPLC (RT = 3.2 - 5.8 minutes) yielded a Log Koc = 2.8 - 6.5.
Adsorption coefficient of main peaks of Butanal, reaction products with aniline determined by HPLC, calculated with area % and their corresponding yielded a mean Log Koc of 4.9 (concentration-weighted mean value).

Key value for chemical safety assessment

Koc at 20 °C:

79 433

Additional information

The adsorption coefficient (Koc) of the test item was determined according to the HPLC method at 40 °C. In order to comply with the guideline OECD 121 and considering environmental relevance, pH 6 was chosen as pH value for the buffer. The reference Koc-values in the OECD-guideline presumably refer to 25 °C. Even though the column temperature was 40 °C, this temperature is without influence on the result of the determination. The calibration was done referring to Koc- values of reference substances determined at 25 °C. For the determination of the adsorption coefficient (Koc) five calibration standards with log Koc from 1.45 - 4.09 are established in the EG-test method. Additionally a new reference substance 9,10-Dimethyl-1,2-benzanthracene (7,12-Dimethylbenzanthracene) was used in this test. The experimental value of log Koc = 5.37 for 9,10-Dimethyl-1,2-benzanthracene was published by Donald A. Bahnick and William J. Doucette in the “Chemosphere, Vol. 17, No. 9, pp 1703-1715, 1988”. The chromatogram of the test item Butanal, reaction products with aniline showed a resolved band of 6 signals. 3 signals were eluted between 4.5 and 5.8 minutes. No calibration substance with a Koc–value above the value for these signals of the test item was available. For this reason the results for these signals were extrapolated. Although the determined value does not exactly meet the range of application of the test guideline (1.3 – 5), we consider the value as valid (measurement uncertainty +/- 0.5 log units). For adsorption coefficient of the test item Butanal, reaction products with aniline determined by HPLC follows:

Adsorption coefficient of main peaks of Butanal, reaction products with aniline determined by HPLC, calculated with area % and their corresponding Log Koc = 4.9.

The range of main peaks of the test item Butanal, reaction products with aniline determined by HPLC, RT = 3.2 - 5.8 minutes yielded a Log Koc = 2.8 - 6.5)

Adsorption coefficient of main peaks of Butanal, reaction products with aniline determined by HPLC, calculated with area % and their corresponding yielded a mean Log Koc of 4.9 (concentration-weighted mean value).

[LogKoc: 4.9]