Reaction mass of 6-(2-ethyl-6-methylanilino)-5-(4-{4-[ethyl(3-sulfobenzyl) amino] phenylazo} phenylazo)-4-hydroxynaphthalene-2-sulfonic acid, sodium and/or disodium salt(s) and 6-(2-ethyl-6-methylanilino)-5-(4-{4-[ethyl(4-sulfobenzyl) amino] phenylazo} phenylazo)-4-hydroxynaphthalene-2-sulfonic acid, sodium and/or disodium salt(s)

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

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

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Test material

Test material information

Constituent 1

Reference substance name:

Acid Navy RN-2682

IUPAC Name:

Acid Navy RN-2682

Test material form:

solid

Study design

HPLC method

Details on study design: HPLC method:

HPLC with UV/vis detector
Reversed phase column and an aqueous mobile phase

Reference solutions
The reference items were chosen from the list given in the OECD guideline 121.
Stock solutions of the reference items were prepared as described:
11.95 mg of isoproturon, 10.58 mg of linuron, 10.59 mg of 2,4-DDT, 9.17 mg of pyrazophos, 9.69 mg of diclofop-methyl and 9.36 mg of acetanilide were each dissolved in 10 ml of methanol.
A combined reference solution was prepared by transferring 144 μl of the acetanilide stock solution, 115 μl of the isoproturon stock solution, 110 μl of the linuron stock solution, 1000 μl of the pyrazophos stock solution, 250 μl of the diclofop-methyl stock solution and 1000 μl of the 2,4-DDT stock solution into one volumetric flask and diluting to a volume of 10 ml with a solvent mixture of water and methanol (45:55; v/v). This reference solution was injected six
times.
Sodium nitrate (9.80 mg) was dissolved in 10 ml of methanol to obtain a stock solution. The stock solution (50 μl) was diluted to 1 ml with a solvent mixture of water and methanol (45:55; v/v). This sodium nitrate solution was injected twice for the determination of the dead time of the HPLC system.

HPLC-conditions
Column: LiChrospher CN, particle size 5 μm, 250 mm × 4 mm
Mobile phase: water / methanol (45:55; v/v); pH 6.55
Detection: test item: 254 nm
Reference items: 210 nm
Sodium nitrate: 254/ 210
Temperature: 25 °C
Injection volume: 10 μl
Flow: 1.0 ml/min
Run time: 15 minutes

Batch equilibrium or other method

Analytical monitoring:

yes

Details on test conditions:

The test item solution was injected three times and the reference solution was injected six times.

Results and discussion

Adsorption coefficient

Type:

log Koc

Value:

< 1.25 dimensionless

Results: HPLC method

Details on results (HPLC method):

Under the conditions of the test, the test item was found to elute as one peak at a retention time of about 1.06 minutes. Sodium nitrate, that was used for the dead time determination, was eluted at a retention time of about 1.18 minutes. The reference item with the lowest Koc was eluted at a retention time of about 2.83 minutes. Test item was not retained under the chromatographic conditions of the test and was eluted at the dead time. The Koc was therefore determined to be lower than that one of the lowest reference item used (acetanilide).

The chromatography of the test item resulted in one main peak with a well-defined and reproducible retention time. The HPLC method was therefore considered to be suitable for the purpose of the study. Based on the chromatographic data, test item was considered to be stable during the test procedure.

Applicant's summary and conclusion

Conclusions:

The log of the adsorption coefficient (Koc) of test item was found to be lower than that one of the lowest reference item acetanilide.
log Koc < 1.25 using the HPLC method.