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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:
guideline study without detailed documentation
Remarks:
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:
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:
4.53
Remarks on result:
other: tetradecan-1-ol
Type:
Koc
Value:
33 983
Remarks on result:
other: tetradecan-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 9.08 min; log k = 0.21; Koc 33983, log Koc 4.53.

Table 1. Comparison of experimentally determined log k and literature log Kocvalues 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 Kocvalues 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 Kocvalues for the test substances, comparison of HPLC and adsorption study results

Compound

Koc

Log Koc

Log Koc

Difference

Possible Correction factor1

Previous experimental data

HPLC

1-hexanol

10.2

1.012

1.25

-0.24

 

 

0.17+0.74

1-dodecanol

17980

4.253

3.71

0.55

1-tridecanol

50830

4.713

4.12

0.59

1-hexadecanol

143000

5.153

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 33983 (log Koc 4.53) was determined in a reliable study conducted according to an appropriate test protocol (OECD 121).
Endpoint:
adsorption / desorption, other
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Remarks:
The result was obtained by the valid application of a well-established predictive method.
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.
GLP compliance:
no
Type of method:
other: QSAR calculation
Type:
Koc
Value:
96 500 L/kg
Remarks on result:
other: Predominantly hydrophobics method
Type:
Koc
Value:
14 300 L/kg
Remarks on result:
other: Non-hydrophobics method
Type:
Koc
Value:
710 L/kg
Remarks on result:
other: Alcohols method. Note, this method is validated only up to log Kow = 5 and is presented for comparison only.
Endpoint:
adsorption / desorption: screening
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:
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:
50 828
Type:
log Koc
Value:
4.71
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 50828 l/kg was determined in a reliable study conducted according to generally accepted scientific principles.

Description of key information

Adsorption/desorption for tetradecan-1-ol: 51300 (batch equilibrium results from WWTP sludge); 33983 (OECD 121).

Key value for chemical safety assessment

Koc at 20 °C:
33 983

Additional information

An estimated Koc value for tetradecan-1 -ol 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 results from this study 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 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.

It is notable that significant technical difficulties were encountered during method development for the study of decan-1 -ol (CAS 112-30-1) in natural standard soils, in that it was not possible to detect sufficient substance and establish equilibrium in non-sterilised soil samples, due to the rapid rate of biodegradation of the test substance by the soil microbiota. The HPLC technique avoids the complications of biodegradation in the soil test substrate.

Koc values in the range 710-97000 for tetradecan-1 -ol 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 Kowand 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 conducted with the structural analogue decan-1 -ol 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 hexan-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 under contract number EV5V-CT92-0211.

[LogKoc: 4.53]