Dodecan-1-ol

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption, other

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

supporting study

Study period:

2004

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Remarks:

The value was predicted using accepted calculation methods.

Justification for type of information:

Please refer to the associated QMRF and QPRF for details of the model validation, input parameters and other remarks. QSAR validation for this endpoint is discussed further in the Alcohols Environmental Fate Category Report.

Principles of method if other than guideline:

Method: other (calculation): various methods

Media:

soil

Type:

Koc

Value:

6 420 L/kg

Remarks on result:

other: Non-hydrophobics method

Type:

Koc

Value:

390 L/kg

Remarks on result:

other: Alcohols method

Type:

Koc

Value:

330 L/kg

Remarks on result:

other: SRC KOCWIN

TGD Non-hydrophobics method: Koc = 6420 l/kg

TGD Alcohols method: Koc = 390 l/kg

SRC PCKOCWIN method: Koc = 330 l/kg

Note: the TGD Alcohols method is valid up to log Kow = 5. The result is presented for comparison only.

Reference 2

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

December 2013

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to an appropriate OECD test guideline. However, no purity data, no pH data, no temperature data and no information on repeatability (number of duplicates) were reported.

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))

GLP compliance:

no

Remarks:

however the study was covered by ISO 17025 certification

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Radiolabelling:

no

Details on study design: HPLC method:

EQUIPMENT
- Apparatus: Agilent 1200 pump, autosampler, and refractive index detector with an EZChrom Elite data system.
- Type:
- Type, material and dimension of analytical (guard) column: Discovery® Cyano 5 µm 250 mm x 4.6 mm analytical column maintained at 40˚C with a 5μm Discovery® Cyano Supelguard™ Cartridge 20 mm × 4.0 mm guard column positioned between the injection system and the analytical column.
- Detection system: Refractive index detection.

MOBILE PHASES
- Type:
- Experiments with additives carried out on separate columns: yes / no: not reported.
- pH: Not reported.
- Solutes for dissolving test and reference substances: methanol.

DETERMINATION OF DEAD TIME
- Method: by inert substances which are not retained by the column (formamide).

REFERENCE SUBSTANCES
- Identity: Phenol, Methyl benzoate, 3,5-Dinitrobenzamide, Naphthalene, 1,2,3-Trichlorobenzene and DDT.

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 5 µl: Test and reference samples were prepared with 0.05 g of test substance in 25 ml of methanol. 5 µl of sample were injected with a flow rate of 1 ml min-1 and a mobile phase of 55% (v/v) methanol and water.
- Quantity of reference substances: 5 µl.
- Intervals of calibration: Not reported.

REPETITIONS
- Number of determinations: Not reported.

EVALUATION
- Calculation of capacity factors k': capacity factor, k, where k = (tr – t0)/t0
- Calculation of retention times: The retention time was determined for each of the reference and test substances, tr, in relation to that of the unretained solute, formamide, t0.
- Determination of the log Koc value: The retention times for a series of reference compounds were determined to form a correlation plot for the calculation of the log organic carbon-water adsorption coefficient for test substances. Linear regression of the organic carbon-water adsorption coefficient (log Koc) of reference substances against the log of capacity factors (log k) of the reference substances determines the linear regression coefficients (a and b). The organic carbon-water adsorption coefficient of a test substance can be calculated by inserting its experimentally determined capacity factor into the below equation:
Log Koc = a + b log k

Type:

log Koc

Value:

3.71

Remarks on result:

other: dodecan-1-ol

Type:

Koc

Value:

5 098

Remarks on result:

other: dodecan-1-ol

Details on results (HPLC method):

- Retention times of reference substances used for calibration: normal (refer to Table 1 below).
- Details of fitted regression line (log k' vs. log Koc): The data demonstrate a good correlation (R2 = 0.9907) between the experimentally derived capacity factor (k) and the literature log Koc values for the reference substances.
- Average retention data for test substance: mean retention time 6.89 min; log k = 0.00; Koc 5098, log Koc 3.71.

Table 1. Comparison of experimentally determined log k and literature log K_ocvalues for the reference substances

Substance	Mean retention time (tr) (min)	Log k (log(tr-t0/t­0))	Literature log Koc
Phenol	4.26	1.27	1.32
Methyl benzoate	4.50	1.70	1.80
3,5-Dinitrobenzamide	4.88	2.23	2.31
Naphthalene	5.58	2.90	2.75
1,2,3-Trichlorobenzene	6.27	3.37	3.16
DDT	13.44	5.49	5.63

Table 2. HPLC-derivedlog K_ocvalues for the range of alcohol test substances

Test substances (alcohols)	Mean retention time (tr) (min)	Log k (log(tr-t0/t0))	Koc	Log Koc
1-hexanol	4.25	-0.64	17.9	1.25
1-heptanol	4.48	-0.53	47.3	1.68
1-octanol	4.77	-0.43	123	2.09
1-nonanol	4.96	-0.36	211	2.32
1-decanol	5.58	-0.21	802	2.90
1-undecanol	6.15	-0.11	2006	3.30
1-dodecanol	6.89	0.00	5098	3.71
1-tridecanol	7.85	0.10	13149	4.12
1-tetradecanol	9.08	0.21	33983	4.53
1-pentadecanol	10.69	0.32	89883	4.95
1-hexadecanol	12.89	0.43	249732	5.40

Table 3. Experimentally derived log K_ocvalues for the test substances, comparison of HPLC and adsorption study results

Compound	Koc	Log Koc	Log Koc	Difference	Possible Correction factor^1
	Previous experimental data		HPLC
1-hexanol	10.2	1.01^2	1.25	-0.24	0.17+0.74
1-dodecanol	17980	4.25^3	3.71	0.55
1-tridecanol	50830	4.71^3	4.12	0.59
1-hexadecanol	143000	5.15^3	5.40	-0.24

1 = mean difference between the methods

2 = Gerstl and Helling (1987)

3 = van Compernolle et al. (2006)

Validity criteria fulfilled:

yes

Conclusions:

An adsorption coefficient (Koc) value of 5098 (log Koc 3.71) was determined in a reliable study conducted according to an appropriate test protocol (OECD 121).

Reference 3

Endpoint:

adsorption / desorption, other

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The study was well documented and meets generally accepted scientific principles, but was not conducted in compliance with GLP.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)

Principles of method if other than guideline:

The radiolabelled test substance was added to a system of natural river water and activated sludge solids (sterilised with mercuric chloride). The concentration of test substance in each phase was determined by LSC following an equilibration period.

GLP compliance:

no

Type of method:

batch equilibrium method

Media:

sewage sludge

Radiolabelling:

yes

Details on sampling:

- Sampling interval: 1,5,16, 30 and 72hrs.

Details on matrix:

- River water: Collected from the River Gowy, Ellesmere Port, UK on two successive daye and mixed and sterilised (0.01% (m/v) mercuric chloride). It contained 12 mg/L suspended solids (SS).

- Activated sludge: Chester, U.K. (United Utilities, Sealand Road) sewage treatment works, a plant that receives mainly (>90%) domestic derived wastewater. Stirred at 150 rpm and aerated for 5 days and then MLSS and mixed liquor volatile suspended solids (MLVSS) were determined according to Standard Methods (APHA, 1995) to be 2940 mg/L and 2210 mg/L, respectively. The total organic carbon was 880 mg/L. The mixture was sterilised and deactivated (mercuric chloride).

Details on test conditions:

TEST CONDITIONS
- Suspended solids concentration: 30 mg SS/L.


TEST SYSTEM
- Type, size and further details on reaction vessel: Four 20 ml of synthetic STP effluent from each 100 ml were pipetted into sperate 300 ml bottles for dilution with 180ml river water and agitated for the specified time period.

- Number of reaction vessels/concentration: Four replicates for each of the sampling times. 100 ± 2 ¿g/L radiolabelled alcohol

- Method of preparation of test solution: 4L activated sludge in 10L aspirators were spiked with stock solution of radiolabelled alcohols and stirred for 24 hours. Spiked activated slude dispensed into five 500ml bottles and gently shaken and allowed to settle for 100 minutes. 100ml subsamples taken to create five synthetic STP effluent bottles having 30 mg SS/L.

Type:

Koc

Value:

17 980

Type:

log Koc

Value:

4.25

Recovery of test material:

Sorption onto the glass fiber filter resulted in 1, 9, 11, 25, and 21 % for the C12, C14, C15, C16 and C18 alcohols, respectively. These values were used to correct the sorption coefficient calculations for alcohols. The total recovery of radioactivity from the filtrate
and filters was 100, 75, 81, 85, and 89 % for C12, C14, C15, C16 and C18, respectively. The remainder of the radioactivity was assumed to be lost to adsorption of alcohols onto glass surfaces during the experiments.

Transformation products:

not measured

Table 1: Alcohol adsorption coefficients (72 hr results)

Carbon number	12	14	15	16	18
Kd	3000±80	8490±920	3080±270	23800±3200	78700±5400
Koc	17980	50830	-	143000	471000
LogKoc	4.25	4.71	-	5.15	5.67

 

C15 was found to be an unexplained outlier.

The results for five substances are considered alongside each other since the results of the whole study are useful for comparison purposes.

QSAR equation developed:

Log Koc = 0.11 + 0.77 log Kow

 

                 R2 = 0.994

Conclusions:

An adsorption coefficient of 17980 l/kg was determined in a reliable study conducted according to generally accepted scientific principles.

Description of key information

A log Koc value of 3.71 was obtained for dodecanol in a reliable study report.

Key value for chemical safety assessment

Koc at 20 °C:

5 098

Additional information

Estimated Koc value for dodecanol has been derived in the HPLC adsorption test (OECD 121), supported by various QSAR methods. A Koc study using HPLC (OECD 121) methodology was conducted for a range of linear aliphatic alcohols in accordance with ISO 17025 (Shell Global Solutions, 2013). The Koc result for dodecan-1-ol from this study was 5098 and the alcohols tested showed a predictable relationship with carbon number. The good performance of the OECD 121 method for alcohols in this category is demonstrated by the close results obtained for the analoguous substance decan-1-ol by OECD 121 as part of the same study and by the batch equilibrium method (OECD 106), which were within a factor of 2 for the same substance.

A recent and reliable study of adsorption and desorption to wastewater treatment plant sludge solids using the batch equilibrium method (in compliance with OECD 106 but not conducted with GLP) has been conducted with dodecan-1-ol. A measured Koc value of 17980 l/kg was obtained using a generally acceptable scientific method. The result is considered to be reliable and is useful for the understanding of the underlying physicochemical adsorption phenomena, but it is important to recognise that the fate and behaviour of alcohols in an active biological sludge system can only be modelled successfully if the important role and rapid degradation is also taken into consideration. The OECD 106 result in sludge is therefore not selected as Key in this data set because the value obtained in this case is higher than expected based on overall trends for the category (though still within a factor of approximately 3 of the expected value based on overall validation trends).

For comparison purposes, Koc values in the range 390-28000 (C12) were obtained using the well-established QSAR calculation method for 'predominantly hydrophobic' substances; the method for 'Alcohol' substances and the method for 'non-hydrophobic' substances, developed by Sabljić and Güsten (1995) for the European Commission, and recommended in EU Guidance. The 'non-hydrophobics' method prediction is closest to the HPLC value in each case. Further details are presented in the endpoint study record.

Discussion of trends in the Category of C6-24 linear and essentially-linear aliphatic alcohols:

Substantial evidence exists within the alcohols Category, in the form of sewage sludge adsorption measurements, literature values, High Performance Liquid Chromatography (HPLC) estimates conducted in accordance with OECD Guideline 121, and a recent OECD Guideline 106 test in soils and a wastewater treatment plant sludge. Predictive methods based on log Kow and MCI have also been explored for members of this Category. The available measured data supports the following conclusions:

- The HPLC predictions correlate very well with the available measured Koc data, requiring no additional correction.

- Adsorption results in the OECD Guideline 106 study indicate that the alcohol interacts only with the organic carbon in the soils. This confirms the expectation that setting a value of Koc is sufficient to understand adsorption to the relevant substrates (soil, sediment, sludges).

- There are no confounding factors anticipated for the alcohols in this Category (e.g. unusual interaction with the stationary phase). Based on the structure and simple physical chemistry of decan-1-ol, there is every reason to believe that the Koc value obtained from the OECD 121 guideline study is valid and fit-for-purpose.

- Different log Kow-based QSAR predictions of Koc vary widely depending on which equation is selected.

- HPLC measured Koc values across the series show a predictable increase in Koc value as the carbon number increases. Regression analysis shows that the linear relationship between carbon number and log Koc value measured using this method is extremely well correlated with very low error.

Reference:

Sabljić A and Güsten H (1995) QSARs for soil sorption. in: overview of structure-activity relationships for environmental endpoints. Hermens JLM (ed), report prepared wtihin the framework of the project "QSAR for prediction of fate and effects of chemicals in the environment", an international project of the Environmental Technologies RTD programme (DG XII/D-1) of the European Commission

[LogKoc: 3.71]