tert-butylbenzene

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:

2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline 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))

Version / remarks:

Adopted 22. Jan. 2001

Deviations:

no

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))

Version / remarks:

Council Regulation (EC) No 440/2008 of 30 May 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Specific details on test material used for the study:

Batch no.: DJ3901A19018
Storage: Room Temperature (20 ± 5°C)

Radiolabelling:

no

Test temperature:

25 ± 0.5 °C

Details on study design: HPLC method:

-HPLC_6
Components: Solvent Rack, Pump LPG-3400SD, Autosampler WPS-3000TSL, Column Compartment TCC-3200 with 6-fold column switch valve UV-Detector MWD-3000
Manufacturer: Thermo Fisher Scientific
Software: CHROMELEON 6.80 SR15b Build 4981
Usage and calibration followed the corresponding SOP 114 00 529 in the current edition

-Method parameters HPLC
Column: Reprosil Pur CN 150*4.6 mm, 5μm with guard column Phenomenex SecurityGuard CN, 4*3 mm
Eluent: isocratic methanol/water 55/45 (% v/v), degassed
Flow rate: 0.8 mL/min
Injection volume: 10 μL
Column temperature: 25.0 ± 0.5 °C.
Wavelength for evaluation: 210 nm (reference item mix), 254 nm (test item)

-MOBILE PHASES
- Type: A mixture of 55% methanol and 45% water, isocratic, was used.
- Experiments with additives carried out on separate columns: no
- pH: 6-7
- Solutes for dissolving test and reference substances: A solution of the test item was prepared by weighing 20.0 mg tert-Butylbenzene into a 20 mL flask and filling up to 20.0 mL with methanol (HPLC Grade) 550 μL of this solution were mixed with 450μL water (HPLC grade), resulting in a solution with a concentration of 550.0 mg/L which was used for the measurements.

DETERMINATION OF DEAD TIME
- Method: by inert substances which are not retained by the column (Dead time marker: Sodium nitrate (CAS#7631-99-4))

REFERENCE SUBSTANCES
- Identity:Sodium nitrate (CAS#7631-99-4), Acetanilid (CAS#103-84-4), Methylbenzoate (CAS#93-58-3), Naphthalene (CAS#91-20-3), 1,2,3-Trichlor-benzene (CAS#87-61-6), Phenanthrene (CAS#85-01-8), 4,4’-DDT (CAS#50-29-3)

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 3
- Quantity of reference substances: 6

REPETITIONS
- Number of determinations: 3

EVALUATION
- Calculation of capacity factors k': k'=(tr-t0)/t0 with tr: retention time, t0: dead time (retention time of sodium nitrate)
- Calculation of retention times: Mean
- Determination of the log Koc value: With the calculated capacity factors for the test item, each log KOC from the three determinations was calculated. Finally, mean and standard deviation of the log KOC were calculated.

Details on sampling:

- Concentrations: 550.0 mg/L
- Sample storage before analysis: Stored in the test facility in a closed vessel at room temperature (20 ± 5 °C).

Key result

Sample No.:

#1

Type:

log Koc

Value:

ca. 2.888 dimensionless

pH:

6

Temp.:

25 °C

Key result

Sample No.:

#2

Type:

log Koc

Value:

ca. 2.888 dimensionless

pH:

6

Temp.:

25 °C

Key result

Sample No.:

#3

Type:

log Koc

Value:

ca. 2.888 dimensionless

pH:

6

Temp.:

25 °C

Details on results (HPLC method):

- Retention times of reference substances used for calibration: 1.024
- Details of fitted regression line (log k' vs. log Koc): log k’ = 0.1948 * logKOC – 0.1363 with a coefficient of determination r2 = 0.9674.
- Average retention data for test substance: 3.757

Validity criteria fulfilled:

yes

Conclusions:

Using the correlation log k’ / log KOC, the log KOC of the peak of the test item tert-Butylbenzene was calculated as 2.888 ± 0.000 (mean ± standard deviation) at a temperature of 25 ± 0.5 °C and a pH value of 6-7 (measured with pH paper).

Executive summary:

Variations in the retention times of reference items and test item are very small. Therefore, a stable configuration of the HPLC-column can be assumed.

The correlation log k’/log KOC is sufficiently accurate, as calibration gave a coefficient of determination r2 = 0.9674.

The chromatogram of the test item gave one peak (mean RT = 3.757 min). With the calibra-tion function log k’ versus log KOC, the corresponding log KOC could be calculated as

2.888 ± 0.000 (mean ± sd).

Therefore, the log KOC of the test item tert-Butylbenzene is stated as 2.89 (mean) at a temperature of 25 ± 0.5 °C and a pH value of 6-7 (measured with pH paper).

No observations were made which might give doubts concerning the validity of the study outcome.

Key value for chemical safety assessment

Koc at 20 °C:

758.579

Additional information

log Koc=2.888 ± 0.000 (mean ± sd) at 25 °C