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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
29-11-2011 to 21-12-2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study performed according to OECD guideline and following GLP principles
Justification for type of information:
The data is read across from a similar substance in a category approach. See chapter 13 for more details
Reason / purpose for cross-reference:
read-across source
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))
Deviations:
yes
Remarks:
Only the ionized form of the test substance was tested
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC estimation method
Test temperature:
30°C
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: HPLC
- Type: Separations model 300 HPLC pump
- Type, material and dimension of analytical (guard) column: Platinum CN 100A 5 µ, 150 mm without guard column
- Detection system: UV/VIS detector Smartline 2500 215 nm

MOBILE PHASES
- Type: Methanol : Buffer solution pH7 15 : 85 (v/v)
- Experiments with additives carried out on separate columns: no
- pH: 7
- Solutes for dissolving test and reference substances: Buffer solution pH7 15 : 85 (v/v)

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

REFERENCE SUBSTANCES
- Identity:
Sodium nitrate
CAS No: 7631-99-4
Supplier: Sigma
Purity: 99.8%
Lot: MKBC9119

Acetanilide
CAS No: 103-84-4
Log Koc = 1.25 (Ref 7)
Supplier: Sigma-Aldrich
Purity: 99.9%
Lot: STBC3743V

Phenol
CAS no: 108-95-2
Log Koc = 1.32 (Ref 7)
Supplier: Sigma-Aldrich
Purity: 99.99%
Lot: BCBB6865

Methylbenzoate
CAS No: 93-58-3
Log Koc = 1.80 (Ref 7)
Supplier: Sigma-Aldrich
Purity: >99.9%
Lot: STBB1195

Naphthalene
CAS no: 91-20-3
Log Koc = 2.75 (Ref 7)
Supplier: Acros
Purity: 99.6%
Lot: A020301301

1,2,3-Trichlorobenzene
CAS no: 87-61-6
Log Koc = 3.16 (Ref 7)
Supplier: Acros
Purity: 99.4%
Lot: A0043055001

Phenantrene
CAS no: 85-01-8
Log Koc = 4.09 (Ref 7)
Supplier: Acros
Purity: 98.7%
Lot: A19660501

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column:
Test substance Concentration injected

aromatic hydrocarbons, C10-13, reaction products with
branched nonene, sulphonated, sodium salts, peak 1 301.5
aromatic hydrocarbons, C10-13, reaction products with
branched nonene, sulphonated, sodium salts, peak 2 7538

- Quantity of reference substances:

(mg/L)
Acetanilide 39.9
Phenol 54.6
Methylbenzoate 112.8
Naphthalene 115.2
1,2,3-Trichlorobenzene 12.1
Phenantrene 7.8
Sodium nitrate (dead time) 153.0
- Intervals of calibration:

REPETITIONS
- Number of determinations: 2

EVALUATION
- Calculation of capacity factors k': k'= (tR- t0)/t0
where tR was the retention time of the test substance, and t0 was the dead-time
- Calculation of retention times:
- Determination of the log Koc value: Log Koc = 1.7531Log k' + 1.5784
Analytical monitoring:
yes
Type:
log Koc
Value:
< 1.25
Temp.:
30 °C
Remarks on result:
other: C1 -C3 alkyl chain part of test substance
Type:
log Koc
Value:
3.5
Temp.:
30 °C
Remarks on result:
other: C10 - C11 alkyl chain part of test substance
Details on results (HPLC method):
- Retention times of reference substances used for calibration:
Substance Avg net retention time (min)
Sodium nitrate 0
Acetanilide 1.25
Phenol 0.81
Methylbenzoate 3.12
Naphthalene 8.05
1,2,3-Trichlorobenzene 10.75
Phenantrene 41.54

- Details of fitted regression line (log k' vs. log Koc):
Log Koc = 1.7531Log k' + 1.5784
R² = 0.9702
- Graph of regression line attached
- Average retention data for test substance:
Substance Avg net retention time (min)
Test substance, peak 1 0.66
Test substance, peak 2 17.27
Validity criteria fulfilled:
yes
Conclusions:
Aromatic hydrocarbons, C10-13, reaction products with branched nonene, sulphonated, sodium had a Koc range of <1.8E+01 – 2.4E+03 (Log Koc <1.25 - 3.4)
Executive summary:

The adsorption coefficient (Koc) of aromatic hydrocarbons, C10-13, reaction products with branched nonene, sulphonated, sodium salts was estimated using the High Performance Liquid Chromatography (HPLC) method. The Koctest was performed in accordance with the OECD guideline 121 with one modification. Despite the test substance was ionisable only the ionized form was tested. The test was performed using a buffer solution pH 7 as aqueous part of the mobile phase in the HPLC set up in order to keep the pH stable during the test. The data on Koccan be used to predict the potential of the test substance to partition to soil, sediment or sewage sludge.

 

During the study two peaks for the test substance were detected. Based on the information provided by the sponsor the peak with the lowest retention time was considered to be representative for the C1 – C3 alkyl chain part of the substance structure whereas the peak with the highest retention time was considered to be representative for the C10 – C11 alkyl chain part of the substance structure.The measured log Kocvalueas calculated from the test for the first peak was <1.25 and for the second peak 3.4.

Description of key information

No sorption/desorption data is available for Sodium diisobutylnaphthalenesulphonate. The sorption data from a structurally similar substance aromatic hydrocarbons, C10-13, reaction products with branched nonene, sulphonated, sodium salts will be read across to Sodium diisobutylnaphthalenesulphonate.

This source substance has a slightly longer alkyl chain than the target substance; Sodium diisobutylnaphthalenesulphonate and is therefore expected to have a slightly stronger sorption. The use of the Koc of the source substance aromatic hydrocarbons, C10-13, reaction products with branched nonene, sulphonated, sodium salts can therefore be considered as a worst-case approach (will lead to higher PECsoil and sediment concentrations).

The log Koc of aromatic hydrocarbons, C10-13, reaction products with branched nonene, sulphonated, sodium salts of 3.5 L/kg was experimentally determined in an adsorption/desorption study according to OECD Guideline 121 under GLP conditions, performed on a substance in the same category.

Key value for chemical safety assessment

Koc at 20 °C:
3 162

Additional information

The adsorption coefficient (Koc) of aromatic hydrocarbons, C10 -13, reaction products with branched nonene, sulphonated, sodium salts was estimated using the High Performance Liquid Chromatography (HPLC) method. The Koctest was performed in accordance with the OECD guideline 121 with one modification. Despite the test substance was ionisable only the ionized form was tested. The test was performed using a buffer solution pH 7 as aqueous part of the mobile phase in the HPLC set up in order to keep the pH stable during the test. The data on Koccan be used to predict the potential of the test substance to partition to soil, sediment or sewage sludge.

 

During the study two peaks for the test substance were detected. Based on the information provided by the sponsor the peak with the lowest retention time was considered to be representative for the C1 – C3 alkyl chain part of the substance structure whereas the peak with the highest retention time was considered to be representative for the C10 – C11 alkyl chain part of the substance structure.The measured log Kocvalueas calculated from the test for the first peak was <1.25 and for the second peak 3.5. The latter value has been used as key value for the CSA.

[LogKoc: 3.5]