reaction mass of: 7-amino-3,8-bis-[4-(2-sulfoxyethylsulfonyl)phenylazo]-4- hydroxynaphthalene-2-sulfonic acid, Na/K salt; 7-amino-3-[4-(2-sulfoxyethylsulfonyl)phenylazo]-4-hydroxy-8-[4-(2-sulfoxyethylsulfonyl)-2- sulfophenylazo]naphthalene-2-sulfonic acid, Na/K salt; 7-amino-8-[4-(2-sulfoxyethylsulfonyl)-phenylazo]-4-hydroxy-3-[4-(2-sulfoxyethylsulfonyl)- 2-sulfophenylazo]naphthalene-2-sulfonic acid, Na/K salt; 7-amino-3,8-bis-[4-(2-sulfoxyethylsulfonyl)-2-sulfophenylazo]-4-hydroxynaphthalene-2- sulfonic acid, Na/K salt

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:

December 17,1998 to February 9,1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Remarks:

Switzerland GLP

Type of method:

batch equilibrium method

Media:

soil

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: TVR50
- Expiration date of the lot/batch: September 1,2004

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature
- Stability under test conditions: Stable for 24 hours
- Solubility of the test substance in the solvent/vehicle: > 80 g/l (at 20 °C)

Radiolabelling:

no

Test temperature:

20 ± 1 °C.

Details on study design: HPLC method:

The following HPLC conditions were developed in a preliminary test. The aqueous phases of all tubes were analysed for parent concentration. Standard solutions were analysed before a series; of samples at each sampling. For each series a linear regression curve was calculated using the standard solution concentrations and the corresponding peak areas. With this linear regression curve the concentrations in the aqueous samples were calculated.

Operating Conditions
Column: 12.5 cm x 4.0 mm, 5 urn Supersphere 100 C18
Flow: 1 ml/minute
Mobile phase:
Solvent A: 1 g TBAPC + 100 ml acetonitrile + 50 ml buffer solution (pH 7) add 1 litre distilled water
Solvent B: 1 g TBAPC + 250 ml distilled water + 50 ml buffer solution (pH 7) add 1 litre acetonitrile
TBAPC: Tetrabutylammoniumperchlorat
Buffer: Merck Titrisol-buffer, Art. no. 9887
Gradient:
Time [min.] 0 20 21 25
%A 95 20 95 95
%B 5 80 5 5
Injection: 50 µl
Retention time: approx. 17 to 18 min.

Analytical monitoring:

yes

Details on matrix:

Three soils: Speyer (loamy sand) Sisseln (sandy loam) and Les Barges (silt loam).

Type:

Koc

Remarks:

Mean of three soil types

Value:

506 other: ml/g

Temp.:

20 °C

% Org. carbon:

2.55

Remarks on result:

other: mean value of the three type of soils (666, 433 and 420 ml/g)

Adsorption

The adsorption test was performed with an application solution (0.01 mol CaCI₂) with 8.21 mg FAT 40'571/A per litre. The volumes of the CaCI₂solutions were determined gravimetrically. The total volume (V₀) of the aqueous phase is the sum of 15 ml application solutions and the 10 ml CaCI₂solution of equilibration of the soil. After 16 h of adsorption, the CaCI₂solution was removed for analysis. Two control tubes without soil were treated correspondingly. The quantity of the test item recovered from the controls was determined to be 120.15 mg/l. This corresponded to 97.6% of the application. No relevant

adsorption of FAT 40'571/A on the tube was observed.

Soils Speyer, Sisseln and Les Barges adsorbed 75.3%, 58.0% and 76.2%, respectively, of FAT 40'571/A within 16 h.

 

Desorption

After 16 hours of adsorption, two desorption steps were performed. From soils Speyer, Sisseln and Les Barges less than 22.5%, 31.6% and 16.8% of the adsorbed FAT 40'571/A was desorbed. The concentrations of FAT 40'571/A desorbed were below the limit of quantification (0.5 mg/l) for the second desorption from all soils and for the first desorption of soil Les Barges. For the calculation of percent desorbed the limit of quantification was used for these concentrations to give an estimation of maximum

desorption.

Correspondingly in the three soils more than 77.4%, 69.8% and 83.2% of the adsorbed amount remained adsorbed. Thus, it can be stated that FAT 40'571/A is strongly adsorbed to the soils tested.

 

Determination of the Adsorption Coefficient

The adsorption coefficient was calculated taking into account the quantity of FAT 40'571/A adsorbed after 16 h, the soil dry mass and the concentration of FAT 40'571/A remaining in solution after 16 h.

The adsorption coefficients K' for FAT 40'571/A in soils Speyer, Sisseln and Les Barges were 15.24 ml/g, 6.81 ml/g and 15.97 ml/g, respectively.

The adsorption coefficient K' can be related to the organic carbon content (in percent) of the soil resulting in a K'oc value. The K'oc value of FAT 40'571/A in soil Speyer, Sisseln and Les Barges was 666 ml/g, 433 ml/g and 420 ml/g, respectively. The respective K'OM values were calculated as 386 ml/g, 251 ml/g and 244 ml/g.

Validity criteria fulfilled:

yes

Conclusions:

The substance can be regarded as little mobile in all three soils (loamy sand, sandy loam and silt loam). The average KOC found was 506 ml/g.

Executive summary:

The adsorption and desorption behaviour of FAT 40'571/A was determined in a screening test by the batch equilibrium method using three soils: Speyer (loamy sand) Sissein (sandy loam) and Les Barges (silt loam). The study was carried out according to OECD 106 guideline. The soils chosen represented a range of organic carbon content, pH, cation exchange capacity and clay content.

A preliminary test was performed to establish a suitable analytical procedure. CaCI₂solutions were analysed for parent by High Performance Liquid Chromatography (HPLC). The substance could be analysed in a concentration range of 0.5 mg/l to 9.0 mg/l. The air-dried soils were conditioned with 0.01 mol CaCI₂per litre solution before the test.

For the screening test, 5 g dried soil equivalents were treated with 25 ml of a 0.01 mol CaCI₂per litre solution containing the test item. This adsorption was performed in duplicate at a concentration of 4.806 mg FAT 40'571/A per litre. The amount of FAT 40'571/A adsorbed to soil was 75.3% for soil Speyer, 58.0% for soil Sissein and 76.2% for soil Les Barges.

After the adsorption, two desorption steps were performed. Therefore, 20-23 ml of untreated 0.01 mol CaCI₂per litre solution was added to the soil sample and the mixture was shaken for 16 hours. From soils Speyer, Sissein and Les Barges less than 22.5%, 31.6% and 16.8% of the adsorbed FAT 40'571/A was desorbed. Corresponding in the three soils more than 77.4%, 69.8% and 83.2% of the adsorbed test item remained adsorbed. The adsorption coefficient K' was calculated as follows:

                                K'oc (ml/g)   Organic Carbon (g/100g dry soil) K'ow (ml/g)

 
- Spayer (loamy sand)      666                2.29                                  386

- Sisseln (sandy loam)     433                1.57                                              251

- Les Barges (silt loam)   420                3.80                                              244

The K'oc values show that FAT 40'571/A is little mobile in all three soils.

Description of key information

The Reactive Brown 49 is a little mobile in all three soils.

Key value for chemical safety assessment

Koc at 20 °C:

506

Additional information

The adsorption and desorption behaviour of Reactive Brown 49 was determined in a screening test by the batch equilibrium method using three soils: Speyer (loamy sand) Sissein (sandy loam) and Les Barges (silt loam). The study was carried out according to OECD 106 guideline. The soils chosen represented a range of organic carbon content, pH, cation exchange capacity and clay content.

A preliminary test was performed to establish a suitable analytical procedure. CaCI₂solutions were analysed for parent by High Performance Liquid Chromatography (HPLC). The substance could be analysed in a concentration range of 0.5 mg/l to 9.0 mg/l. The air-dried soils were conditioned with 0.01 mol CaCI₂per litre solution before the test.

For the screening test, 5 g dried soil equivalents were treated with 25 ml of a 0.01 mol CaCI₂per litre solution containing the test item. This adsorption was performed in duplicate at a concentration of 4.806 mg Reactive brown 49 per litre. The amount of Reactive brown adsorbed to soil was 75.3% for soil Speyer, 58.0% for soil Sissein and 76.2% for soil Les Barges.

After the adsorption, two desorption steps were performed. Therefore, 20-23 ml of untreated 0.01 mol CaCI₂per litre solution was added to the soil sample and the mixture was shaken for 16 hours. From soils Speyer, Sissein and Les Barges less than 22.5%, 31.6% and 16.8% of the adsorbed Reactive Brown 49 was desorbed. Corresponding in the three soils more than 77.4%, 69.8% and 83.2% of the adsorbed test item remained adsorbed. The adsorption coefficient K' was calculated as follows:

 

                               K'oc (ml/g)   Organic Carbon (g/100g dry soil) K'ow (ml/g)

 
- Spayer (loamy sand)      666                2.29                                 386

- Sisseln (sandy loam)     433                1.57                                              251

- Les Barges (silt loam)   420                3.80                                              244