4-(4-nitrophenylazo)-2,6-di-sec-butyl-phenol

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:

2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted under GLP

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

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:

no

Principles of method if other than guideline:

N/A

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

other: ultrapure water

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
N/A

Radiolabelling:

no

Test temperature:

30°C

Details on study design: HPLC method:

EQUIPMENT
- Apparatus: HPLC System
- Type: Agilent 1290 Series
- Type, material and dimension of analytical (guard) column: Agilent ZORBAX SB-CN; 4.6 x 100 mm; 1.8-micron
packing
- Detection system: G4212A Diode Array Detector (at 210 nm)

MOBILE PHASES
- Type: methanol/water (55%/45%; v/v)
- Solutes for dissolving test and reference substances: methanol followed by secondary dilutions in methanol/water (55%/45%; v/v)

DETERMINATION OF DEAD TIME
-Method: analysis of Urea which is not retained by the column

REFERENCE SUBSTANCES
- Identity: acetanilide, methyl benzoate, naphthalene, 1,2,3-trichlorobenzene,
phenanthrene and DDT

REPETITIONS
- Number of determinations: 2

EVALUATION
- Calculation of capacity factors k': k’ = (tR-to)/to
- Calculation of retention times: per Agilent integration software
- Determination of the log Koc value: The log Koc data for the reference materials were plotted against their associated log k’
values and a linear regression line was determined. Estimated log Koc values for the test
material were determined from its measured capacity factor using the equation for the
linear regression line.

Details on sampling:

N/A

Details on matrix:

N/A

Details on test conditions:

N/A

Computational methods:

N/A

Type:

log Koc

Value:

> 5.63

Temp.:

30 °C

Details on results (HPLC method):

- Retention times (min.) of reference substances used for calibration:
Acetanilide: Std 1 (1.294, 1.294), Std 2 (1.296, 1.294)
Methyl Benzoate: Std 1 (1.637, 1.638), Std 2 (1.639, 1.641)
Napthalene: Std 1 (2.364, 2.365), Std 2 (2.367, 2.368)
123 TCB: Std 1 (3.087, 3.091), Std 2 (3.091, 3.092)
Phenathrene: Std 1 (4.904, 4.906), Std 2 (4.904, 4.905)
DDT: Std 1 (13.397, 13.333), Std 2 (13.400, 13.335)

- Details of fitted regression line (log k' vs. log Koc): y = 2.9853x + 2.1266, R² = 0.9952
- Average retention data for test substance: >13.4 minutes

Adsorption and desorption constants:

N/A

Recovery of test material:

N/A

Concentration of test substance at end of adsorption equilibration period:

N/A

Concentration of test substance at end of desorption equilibration period:

N/A

Details on results (Batch equilibrium method):

N/A

Statistics:

N/A

N/A

Validity criteria fulfilled:

not applicable

Conclusions:

In the defined HPLC assay of OECD Guideline 121, no clear chromatographic peak for
the test material was observed under the specified elution conditions. Additional analyses
were performed using an eluent containing a higher organic solvent (methanol)
concentration and showed that MORTRACE™ SB Conc has a log Koc value of > 5.63
(i.e., the highest log Koc value from among the reference materials). This result is
consistent with an estimate based on correlation of estimated log Kow and log Koc values
(KOCWIN v2.00) which gives a log Koc value of 5.8. The MORTRACE™ SB Conc is
therefore concluded to have very high affinity for partitioning from water to organic
matter associated with soil, sediment, and activated sludge biosolids.

Executive summary:

The soil adsorption coefficient (Koc) for MORTRACE™ SB Conc was estimated using the OECD Guideline 121: “Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC).” This method compares the retention time of the test material in a defined HPLC assay to the retention times of a series of reference materials with known Koc values. The reference materials included acetanilide, methyl benzoate, naphthalene, 1,2,3-trichlorobenzene, phenanthrene, and DDT. The HPLC capacity factors (k’) for the test and reference materials were derived from their retention times, as corrected for the dead volume in the HPLC column. The log Koc values of the reference materials were plotted against their corresponding log k’ values and a linear regression line was obtained. The Koc of the test material was then estimated from its measured HPLC capacity factor k’ using the equation for the regression line (log Koc vs. log k’). In the guideline-defined HPLC assay, no chromatographic peak for the test material was observed under the specified elution conditions. Additional analyses were performed using an eluent containing a higher organic solvent (methanol) concentration, which showed that MORTRACE™ SB Conc has a log Koc value of >5.63 (i.e., the highest log Koc value from among the reference materials). Therefore, the substance can be concluded to have a high affinity for partitioning from water to organic carbon associated with soil, sediment, and activated sludge biosolids.

Description of key information

Based on the experimental data, the log Koc for Mortace SB Conc was determined to be >5.63.

Key value for chemical safety assessment

Koc at 20 °C:

426 580

Additional information

The soil adsorption coefficient (Koc) for MORTRACE™ SB Conc was estimated using the OECD Guideline 121: “Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC).” This method compares the retention time of the test material in a defined HPLC assay to the retention times of a series of reference materials with known Koc values. The reference materials included acetanilide, methyl benzoate, naphthalene, 1,2,3-trichlorobenzene, phenanthrene, and DDT. The HPLC capacity factors (k’) for the test and reference materials were derived from their retention times, as corrected for the dead volume in the HPLC column. The log Koc values of the reference materials were plotted against their corresponding log k’ values and a linear regression line was obtained. The Koc of the test material was then estimated from its measured HPLC capacity factor k’ using the equation for the regression line (log Koc vs. log k’). In the guideline-defined HPLC assay, no chromatographic peak for the test material was observed under the specified elution conditions. Additional analyses were performed using an eluent containing a higher organic solvent (methanol) concentration, which showed that MORTRACE™ SB Conc has a log Koc value of >5.63 (i.e., the highest log Koc value from among the reference materials). Therefore, the substance can be concluded to have a high affinity for partitioning from water to organic carbon associated with soil, sediment, and activated sludge biosolids.

This experimentally derived Log Koc is consistent with that predicted using the QSAR algorithm implemented in KOCWIN v. 2.00 a module of the Epi Suite program (U.S. Environmental Protection Agency, 2000-2011). The predicted values for Log K_ocbased on the MCI and Log K_owmethods were 5.81 and 5.28, respectively. There was slightly better performance of the analogues in the Log K_owmodel; therefore, preference was given to the value calculated with the Log K_owmodel (i.e.Log K_oc= 5.28).

Confidence intervals were derived based on the error histogram provided by the developer that indicated that 95% of the substances in the training dataset were predicted within +/- 0.7 units of the experimental error.

[LogKoc: 5.63]