Reaction mass of 3,7-dimethyl-1-octyl acetate and citronellyl acetate

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:

05 Jan 2018

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))

Version / remarks:

2016

Deviations:

no

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:

2001

Deviations:

no

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

soil

Radiolabelling:

no

Test temperature:

Column temperature: 35°C ± 1°C

Details on study design: HPLC method:

PKA CALCULATION
pKa acidic: none; pKa basic: none (Perrin calculation method for the logarithm range of 1 - 14, pKalc 5.0, module in Pallas 3.0, CompuDrug International, USA).

HPLC CONDITIONS
- Apparatus: Acquity UPLC system (Waters, USA)
- Column: Acquity UPLC HSS Cyano, 100 mm x 2.1 mm i.d., dp = 1.8 µm (Waters)
- Injection volume: 5 μL
- Detector: Acquity UPLC TUV (Waters)
- UV detection: 210 nm

MOBILE PHASE
- Type: unbuffered mobile phase
- Composition: 55/45 (v/v) methanol/water
- Flow: 0.4 mL/min

DETERMINATION OF DEAD TIME
- Method: by inert substance which is not retained by the column
- A solution of formamide was prepared in 55/45 (v/v) methanol/water from a stock solution (5 g/L) in methanol.

REFERENCE ITEMS
- Identity: Acetanilide, Monuron, 2,5-Dichloroaniline, Naphthalene, Benzoic acid phenylester, Fenthion, Phenanthrene and 4,4’-DDT.
- Solutions of the reference items were prepared in 55/45 (v/v) methanol/water from stock solutions (ca. 1 g/L) in methanol.

TEST ITEM
- A 10 mg/L test item solution was prepared in 55/45 (v/v) methanol/water from a stock solution (1 g/L) in methanol.

DETERMINATION OF RETENTION TIMES
- Duplicate injections of the unretained substance, reference items and test item.
- Single injection of the blank (55/45 (v/v) methanol/water).

DATA HANDLING
- Dead time (t0) = mean retention time of the unretained substance
- Calculation of capacity factor k' of each compound from its retention time : k' = (tr-t0)/t0
- Log k’ values (references items) were plotted against their known log Koc values using linear regression analysis (least squares method).
- Log Koc of the substance was calculated by substituting its mean log k’ in the regression line (log k' vs log Koc).

Type:

Koc

Value:

7 100 L/kg

Temp.:

20 °C

Remarks on result:

other: for the constituents with peak area of 65%

Type:

log Koc

Value:

3.85 dimensionless

Temp.:

20 °C

Remarks on result:

other: For the constituent with peak area of 65%. Unbuffered mobile phase.

Key result

Type:

Koc

Value:

3 300 L/kg

Temp.:

20 °C

Remarks on result:

other: for the constituents with peak area of 65%

Remarks:

Citronellyl Acetate mono

Type:

log Koc

Value:

3.52 dimensionless

Temp.:

20 °C

Remarks on result:

other: For the constituent with peak area of 35%. Unbuffered mobile phase.

Details on results (HPLC method):

- Retention times of reference items used for calibration: see table below
- Details of fitted regression line: log k’ = 0.304 log Koc– 0.878 (r=0.98, n=16)
- Graph of regression line attached.
- The chromatogram of the test item showed two major test item peaks.
- Average retention data for the test item: see table below
- The value of log Koc obtained from duplicate measurements was within ± 0.25 log units.

Table: Results Adsorption coefficient (HPLC estimation method)

Substance	Retention time (min)			log Koc	Koc	Peak area (%)
	RT1	RT2	mean
Formamide (t0)	0.688	0.688	0.688
Acetanilide	0.874	0.873		1.26
Monuron	1.046	1.042		1.99
2,5-Dichloroaniline	1.157	1.156		2.55
Naphthalene	1.323	1.322		2.75
Benzoic acid phenylester	1.540	1.529		2.87
Fenthion	1.965	1.957		3.31
Phenanthrene	2.177	2.157		4.09
4,4’-DDT	4.754	4.729		5.63
Test item – peak 1	1.760	1.758	1.759	3.52	3.3E3	35
Test item – peak 2	2.036	2.034	2.035	3.85	7.1E3	65

Remark: the log Koc values of the reference items are as mentioned in OECD TG 121 (based on soil adsorption data).

Validity criteria fulfilled:

yes

Remarks:

The study is performed according to the guidelines

Conclusions:

Using the HPLC estimation method, the log Koc at neutral pH and ca. 20°C for the constituent with peak area of 65% was determined to be 3.85 (Koc= 7.1E3). The log Koc for the constituent with peak area of 35% was determined to be 3.52 (Koc= 3.3E3).

Executive summary:

The adsorption coefficient (Koc) of the substance was determined using the HPLC estimation method based on soil-adsorption reference data. The study was performed in accordance with EC C.19 and OECD 121 and in compliance with GLP. Formamide was used as unretained substance. For the construction of the regression line, 8 references substances with known log Koc values (at ca. 20°C) in the range of 1.26 and 5.63 were used. Duplicate injections of unretained substance, reference items and test item in an UPLC-UV system. The mobile phase was 55/45 (v/v) methanol/water and the wavelength of detection was 210 nm. The stationary phase contained cyanopropyl chains chemically bonded to silica. Each chromatogram of the test item showed two test item peaks. The corresponding log Koc values were calculated from the regression line.

The log Koc at neutral pH and ca. 20°C for the constituent with peak area of 65% was determined to be 3.85 (Koc= 7.1E3). The log Koc for the constituent with peak area of 35% was determined to be 3.52 (Koc= 3.3E3). The value of 3.85 will therefore be the main value for this substance.

Description of key information

The adsorption coefficient (Koc) of the substance was determined using the HPLC estimation method based on soil-adsorption reference data. The study was performed in accordance with EC C.19 and OECD 121 and in compliance with GLP. Formamide was used as unretained substance. For the construction of the regression line, 8 references substances with known log Koc values (at ca. 20°C) in the range of 1.26 and 5.63 were used. Duplicate injections of unretained substance, reference items and test item in an UPLC-UV system. The mobile phase was 55/45 (v/v) methanol/water and the wavelength of detection was 210 nm. The stationary phase contained cyanopropyl chains chemically bonded to silica. Each chromatogram of the test item showed two test item peaks. The corresponding log Koc values were calculated from the regression line.

The log Koc at neutral pH and ca. 20°C for the constituent with peak area of 65% was determined to be 3.85 (Koc= 7.1E3). The log Koc for the constituent with peak area of 35% was determined to be 3.52 (Koc= 3.3E3). The value of 3.85 will therefore be the main value for this substance.

Key value for chemical safety assessment

Koc at 20 °C:

7 100