Decanoic acid, mixed esters with dipentaerythritol, octanoic acid and valeric acid

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

30 Apr 2021 to 07 May 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

OECD Guideline 121. Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC). January 22, 2001.

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EC Technical Guidance Document on Risk Assessment Part III

Version / remarks:

EC Technical Guidance Document on Risk Assessment Part III Chapter 4.3: Use of (Quantitative) Structure Activity Relationships ((Q)SARs) - Soil and Sediment Sorption. 2003.

Deviations:

no

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Specific details on test material used for the study:

No further details specified in the study report.

Radiolabelling:

no

Test temperature:

35°C ± 1°C

Details on study design: HPLC method:

Performance of the Study
The principle of the test method is similar to that of the OECD guideline no. 117: "Partition coefficient (n-octanol/water), high performance liquid chromatography (HPLC) method". While passing through the column along with the mobile phase the test item interacts with the stationary phase. As a result of partitioning between mobile and stationary phases, the test item is retarded. The dual composition of a cyanopropyl stationary phase, having polar and non-polar sites allows for interaction of polar and non-polar groups of a molecule in a similar way as is the case for organic matter in soil or sewage sludge matrices. This enables the relationship between the retention time on the column and the Koc on organic matter to be established.
According to the guidelines, the determination of the Koc for test items that are ionized for at least 10% within pH 5.5 to 7.5 should be performed with both the ionized and non-ionized form. Based on the provided information by the sponsor, it was expected that the test item is not ionized within pH 5.5 to 7.5, and therefore the HPLC method was performed at neutral pH.
Solutions of reference substances with known log Koc values based on soil adsorption data and the test item were analyzed. The capacity factor (k') of each compound was calculated from its retention time. The log k’ values of the references substances were plotted against the known log Koc values. A linear regression program was used to calculate the calibration curve. Linear regression analysis was performed using the least squares method. The coefficient of correlation (r) was calculated. The log Koc value for the test item was calculated by substituting its mean log k’ in the calibration curve. The value of log Koc obtained from duplicate measurements was within ± 0.25 log units.

Analytical Method
Analytical Conditions
Instrument: Acquity UPLC system (Waters, Milford, MA, USA)
Detector: Acquity UPLC TUV detector (Waters)
Column: Acquity UPLC HSS Cyano, 100 mm x 2.1 mm i.d., dp = 1.8 µm (Waters)
Column temperature: 35°C ± 1°C
Injection volume: 1 µL (test item solution and corresponding blank solution)
Injection volume: 5 µL (Unretained Compound solution, Reference Substance Solution and corresponding blank)
Solvent A: acetonitrile
Solvent B: water
Gradient:
Time Solvent A Solvent B
[minutes] [%] [%]
0 50 50
60 50 50
61 95 5
70 95 5
71 50 50
80 50 50

Flow: 0.4 mL/min
UV detection: 210 nm

Preparation of Solutions
Solution of the Unretained Compound
A 5 g/L stock solution of formamide (99.3%, [75-12-7], Alfa Aesar, Karlsruhe, Germany) in methanol was used. The stock solution was diluted to obtain an end solution of 55/45 (v/v) methanol/water.
The formamide blank solution was 55/45 (v/v) methanol/water.

Reference Substance Solution
Stock solutions of the reference substances at concentrations of approximately 1 g/L in methanol or acetonitrile were used. The stock solutions were diluted to obtain an end solution of 55/45 (v/v) methanol/water.
The blank solution for the mixture of reference substances was 55/45 (v/v) methanol/water.

Test Solution
A 8000 mg/L stock solution of the test item was prepared in methanol.
The test item blank solution was methanol.

Sample Injections
Reference substance and test item solutions were injected in duplicate. Blank solutions were analyzed by single injection.

Key result

Sample No.:

#1

Type:

log Koc

Value:

8.58 dimensionless

Temp.:

35 °C

Matrix:

Soil/Sludge

Key result

Sample No.:

#2

Type:

log Koc

Value:

9.46 dimensionless

Temp.:

35 °C

Matrix:

Soil/Sludge

Details on results (HPLC method):

In the chromatogram of the test item solution, in total 42 test item specific signals were detected with varying signal intensity. Only the relevant peaks were used for determination of the Koc and log Koc values. The first and second peak had retention times below 0.906 min (log Koc < 1.26, relative peak area <5%). The third peak had a retention time of 1.44 minutes (log Koc between 2.55 and 2.75, relative peak area <0.25%). The fourth and fifth peak had a retention time between 1.77-1.92 minutes (log Koc between 2.87 and 3.31, relative peak area <3.7%). The sixth till seventieth peak had a retention time between 2.15-4.43 minutes (log Koc between 4.09 and 5.63, relative peak area <4.5%). Under the same analytical conditions, the retention time of 4,4’-DDT (log Koc = 5.63) was 4.4 minutes. All other peaks in the chromatogram appeared at retention times of > 4.4 minutes and a log Koc > 5.63. The responses of the five largest peaks of these peaks were used for calculation of the Koc and log Koc values. These calculated values were extrapolated from the curve.

Koc of the Test Item

Substance	Retention time (min)			Log Koc	Koc	Peak area (%)
	tr1	tr2	Mean
Formamide (t0)	0.681	0.677	0.679
Acetanilide	0.906	0.903		1.26
Monuron	1.062	1.058		1.99
2,5-Dichloroaniline	1.381	1.373		2.55
Naphthalene	1.562	1.553		2.75
Benzoic acid phenylester	1.721	1.716		2.87
Fenthion	2.110	2.100		3.31
Phenathrene	2.131	2.118		4.09
4,4’-DDT	4.405	4.377		5.63
Test item – peak 18	4.927	4.929	4.928	5.56	3.6 x 10^5	3.5
Test item – peak 37	16.460	16.486	16.473	7.68	4.7 x 10^7	18
Test item – major peak 1	28.255	28.325	28.290	8.58	3.8 x 10^8	31
Test item – peak 41	40.862	40.900	40.881	9.18	1.5 x 10^6	19
Test item – major peak 2	48.438	48.446	48.442	9.46	2.9 x 10^9	29

Minor compound 1 and 2 have a log Koc below 1.26 and a relative area below 5%

Minor compound 3 has a log Koc inbetween 2.55 and 2.75 and a relative area below 0.25%

Minor compound 4 and 5 have a log Koc inbetween 2.87 and 3.31 and relative areas below 3.7%

Minor compound 6 till 17 have a log Koc inbetween 4.09 and 5.63 and relative areas below 4.5%

Validity criteria fulfilled:

not specified

Conclusions:

The HPLC method using soil-adsorption-reference data was applied for the determination of the adsorption coefficient (Koc) of Decanoic acid, mixed esters with dipentaerythritol, octanoic acid and valeric acid.
The Koc and log Koc values of the test item at neutral pH were:
Koc Log Koc Peak area
(%)
Test item – peak 18 3.6 x 105 5.56 3.5
Test item – peak 37 4.7 x 107 7.68 18
Test item – major peak 1 3.8 x 108 8.58 31
Test item – peak 41 1.5 x 109 9.18 19
Test item – major peak 2 2.9 x 109 9.46 29
Minor compound 1 and 2 have a log Koc below 1.26 and a relative area below 5%
Minor compound 3 has a log Koc between 2.55 and 2.75 and a relative area below 0.25%
Minor compound 4 and 5 have a log Koc between 2.87 and 3.31 and relative areas below 3.7%
Minor compound 6 till 17 have a log Koc between 4.09 and 5.63 and relative areas below 4.5%

Executive summary:

The objective of this study was to determine the adsorption coefficient of Decanoic acid, mixed esters with dipentaerythritol, octanoic acid and valeric acid.

 

The summary of the results is listed below:

Information	Guideline(s)	Peak (retention time)^1	Result log Koc	Comment
Adsorption coefficient	EC C.19 OECD 121	Log Koc major 1 (28.3) Log Kc major 2 (48.4) Test item peak 18 (4.9) Test item peak 37 (16.5) Test item peak 41 (40.9)	8.58 9.46 5.56 (minor) 7.68 (minor) 9.18 (minor)	HPLC method based on soil-adsorption-reference data

¹Test item is an UVCB. 42 peaks were observed in the chromatograms. The calculated log Koc values are based on the total peak area (approximately 60%) of the two major peaks and three largest minor peaks.

Description of key information

Log Koc major 1 = 8.58

Log Koc major 2 = 9.46

Key value for chemical safety assessment

Koc at 20 °C:

19 952

Additional information

The objective of this study was to determine the adsorption coefficient of Decanoic acid, mixed esters with dipentaerythritol, octanoic acid and valeric acid.

 

The summary of the results is listed below:

Information	Guideline(s)	Peak (retention time)^1	Result log Koc	Comment
Adsorption coefficient	EC C.19 OECD 121	Log Koc major 1 (28.3) Log Kc major 2 (48.4) Test item peak 18 (4.9) Test item peak 37 (16.5) Test item peak 41 (40.9)	8.58 9.46 5.56 (minor) 7.68 (minor) 9.18 (minor)	HPLC method based on soil-adsorption-reference data

¹Test item is an UVCB. 42 peaks were observed in the chromatograms. The calculated log Koc values are based on the total peak area (approximately 60%) of the two major peaks and three largest minor peaks.