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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
19 January 2004 to 24 February 2004
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Remarks:
A GLP compliant study performed to standardised guidelines with limited amount of detail on the materials and methods.
Qualifier:
according to
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:
(see below)
Principles of method if other than guideline:
The test substance eluted after the standard with the highest literature Koc. Therefore the sample was not bracketed by standards with higher and lower Koc values as per protocol. The test substance log Koc was reported as a value greater than the standard having the highest log Koc value. As per protocol, the dead time was not measured because it was not necessary to calculate the capacity factor since the test substance eluted after the highest log Koc reference standard. These protocol deviations had no effect on the outcome of the study.
GLP compliance:
yes
Type of method:
HPLC estimation method
Radiolabelling:
no
Test temperature:
26 ± 1 ºC
Details on study design: HPLC method:
INSTRUMENT CONDITIONS
The samples were analysed using HPLC/UV with the following instrument conditions:

Instrument: Waters Module I Plus liquid chromatograph
Detector: Waters Module I Plus (486 internal) at 254 nm
Column: ThermoHypersil-Keystone, CPS-2 Hypersil, 150 x 3 mm i.d., 5 µm particle size
Solvent A: 0.01 M citrate buffer in distilled, deionized water, pH adjusted to 3.00 with concentrated citric acid
Solvent B: methanol
Injection size: 20 µL
Flow: 0.5 mL/min
Elution conditions: isocratic at 75 % B for 5 minutes

The standard used in this study was: DDT (1,1-bis(4-chlorophenyl)-2,2,2-trichlorethane).

The standard and the test substance were dissolved in methanol at working concentrations of approximately 1500 mg/L and 1200 mg/L, respectively.
Key result
Type:
log Koc
Value:
> 5.63
Temp.:
26 °C
Details on results (HPLC method):
HPLC results of standard and test substance:
- Test substance: Mean retention time: 3.156 minutes; concentration: 1200 mg/L; Literature log Koc: not applicable
- DDT: Mean retention time: 2.859 minutes; concentration: 1460 mg/L; Literature log Koc: 5.63
Transformation products:
not specified

One standard with a known log Koc value was prepared and analysed with the test substance. The test substance was not bracketed by standards with higher and lower log Koc values. The test substance eluted after the DDT standard which is the standard having the highest literature log Koc value. Therefore, the log Koc of the test substance was estimated to be > 5.63. Since the log Koc value of the test substance was reported as a greater than value, an unretained organic compound was not analysed for the dead time determination.

The test substance was estimated to have three pKa values; 1.1, 7.5 and 13.1. Therefore the test substance is considered ionizable. Due to pH limits of the analytical column (pH 2 to 8) it was not possible to analyse the test substance in its nonionized form since this would require using a buffered water mobile phase at a pH one unit below 1. The test substance was analysed in its ionized form using a buffered water mobile phase at a pH of 3.00.

Validity criteria fulfilled:
not applicable
Remarks:
Due to the nature of the test material, the validity criteria of the testing guideline cannot be applied.
Conclusions:
Under the conditions of the test, the Koc of the test substance was estimated to be greater than 5.63.
Executive summary:

In a GLP adsorption-desorption study conducted in line with OECD Guideline 121, the Koc of butanoic acid, 4-[[4-[7-chloro-6 -(1,1-dimethylethyl)-3H-pyrazolo[1,5-b][1,2,4]triazol-2-yl]phenyl]amino]-4-oxo, tetradecyl ester was determined using HPLC. The Koc of the substance was estimated to be greater than 5.63.

Description of key information

Key study:- Isaacs (2004b) 'Estimation of the adsorption coefficient (Koc) on soil and on sewage sludge using high performance liquid chromatography' was conducted in line with OECD Guideline 121. The Koc of the test substance was estimated to be greater than 5.63.

Key value for chemical safety assessment

Additional information

The key study (Isaacs, 2004b) was performed in compliance with GLP and to OECD Guideline 121 with a sufficient level of detail to assess the quality of the presented data. The study was performed to a good standard in line with an accepted, standardised guideline and was assigned a reliability score of 2 using the principles for assessing data quality as set out in Klimisch et al. (1997). The Koc of the test substance was estimated to be greater than 5.63.