Humic acids and fulvic acids extracted from leonardite, reaction product with formaldehyde, potassium hydrogen sulfite, sodium hydrogen sulfite and potassium hydroxide

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

from November 19, 2007 to Januar 15, 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study was carried out in accordance with internationally valid GLP principles.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

Deviations:

yes

Remarks:

The HPLC is only applic. to subst. with log Koc values from 1.5 to 5.0. This subst. does not meet this requirement, at all. The reten. time of the subst. was comparable to the dead time of the column and it was much lower than references substances.

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:

Humic acids, potassium salts

EC Number:

271-030-1

EC Name:

Humic acids, potassium salts

Cas Number:

68514-28-3

IUPAC Name:

68514-28-3

Details on test material:

- Name of test material (as cited in study report): Humic acids, potassium salts
- Molecular formula: not known - UVCB substance
- Molecular weight: not known - UVCB substance
- Substance type: technical product
- Physical state: solid
- Lot/batch No.: 16. 5. 2007/R
- Expiration date of the lot/batch: 05/2022
- Stability under test conditions: stable
- Storage condition of test material: dry conditions

Radiolabelling:

no

Study design

Test temperature:

25ºC

HPLC method

Details on study design: HPLC method:

EQUIPMENT
- Apparatus:
- Type: Liquid chromatograph – Shimadzu LC-2010AHT
- Type, material and dimension of analytical (guard) column: Column – ZORBAX CN, 5um, 150 x 4.6 mm
- Detection system: UV/VIS detector
Detection: 210 nm - NaNO3
240 nm - the reference substances
300 nm - the test substance
Flow: 1.0 mL / min
Injection volume: 10 uL - NaNO3 and calibration mixtures
20 uL - the test substance
Column temp.: 25°C

MOBILE PHASES
- Type: water-methanol
Mobile phase
550 mL of 0.01M citrate-buffer pH = 6.1 was mixed with 450 mL of methanol.
Mobile phase preparation
0.01M citrate-buffer pH = 6.1
0.96g of citric acid was dissolved in ca 400 mL water; pH of this solution was adjusted to 6.1 with 1M NaOH and diluted to 500 mL with water.

- Experiments with additives carried out on separate columns: no
- pH: 6.1
- Solutes for dissolving test and reference substances: mobile phase

DETERMINATION OF DEAD TIME
- Method: by inert substances which are not retained by the column
dead time =“retention” time of natrium nitrate

REFERENCE SUBSTANCES
- Identity:
Acetanilide
Aniline
Atrazin
Benzamide
2,5-Dichloraniline
Phenyl benzoate
2-Nitrobenzamide

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 4 micrograms
- Quantity of reference substances: cca 10 micrograms

REPETITIONS
- Number of determinations: 4

Results and discussion

Adsorption coefficient

Type:

log Koc

Value:

< 1.3

Temp.:

25 °C

Results: HPLC method

Details on results (HPLC method):

Adsorption coefficient of Humic acids, potassium salts on soil:
log Koc (soil) < 1.3 (pH = 6.1, 25°C)

Adsorption coefficient of Humic acids, potassium salts on sewage sludge:
log Koc (sludge) < 1.5 (pH = 6.1, 25°C)

Applicant's summary and conclusion

Validity criteria fulfilled:

no

Conclusions:

Only one validity criterium was not fulfilled:
The HPLC method is only applicable to chemical substances with log Koc values ranging from 1.5 to 5.0. The test substance, Humic acids, potassium salts, does not meet this requirement, at all. The retention time of the test substance was comparable to the dead time of the column and it was much lower than that of any reference compound.
It can be concluded with an assurance, that a value of the log Koc of the test substance is lower than the lowest value used for calibration.

Executive summary:

The adsorption coefficient of test substance on soil and on sewage sludge was estimated.

The HPLC method with reference compounds was used.

The test was performed according to the Method C.19, Estimation of the adsorption coefficient (K_OC) on soil and sewage sludge using high performance liquid chromatography (HPLC), Directive 2001/59/EC. Published in O.J. L 225, 2001.

Adsorption coefficient of Humic acids, potassium salts on soil:

log Koc (soil) < 1.3 (pH = 6.1, 25ºC)

Adsorption coefficient of Humic acids, potassium salts on sewage sludge:

log Koc (sludge) < 1.5 (pH = 6.1, 25ºC)

The retention time of the test substance, Humic acids, potassium salts, was much lower than that of any reference compound and thus it is not possible to calculate its adsorption coefficients. Furthermore, neither their approximate estimation is allowed to be done because the retention time of the test substance is even shorter than the dead time determined and therefore the capacity factor of the test substance is not defined.