2-tert-butyl-1,4-dimethoxybenzene

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:

2018-07-06 to 2018-07-07

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:

OECD Guidelines for the Testing of Chemicals; Guide 121 Estimation of the Adsorption Coefficient (KOC ) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

other: cyanopropyl stationary phase with methanol:water eluent

Specific details on test material used for the study:

Test item name: Vetimoss
Laboratory master schedule: 4419
Chemical name: 2-tert-butyl-1,4-dimethoxybenzene
Batch: A180118C
Appearance: Clear, pale yellow liquid
Expiry date: 6 June 2019
Purity: 98.0%
Storage conditions: Protected from humidity (tight closed container) and under inert gas

Radiolabelling:

no

Test temperature:

Column temperature: 55°C

Details on study design: HPLC method:

The purpose of this study was to estimate the adsorption coefficient of Vetimoss test item. The determination is based on the measurement of the retention time of the test item on cyanopropyl stationary phase with methanol:water eluent (according to OECD 121 guideline).

APPARATUS
- HPLC-UV instrument: Dionex Ultimate 3000 UHPLC
- Balance: Sartorius-CPA225D
- Ultrasonic bath: Sonis 10
- Micropipette 20 – 200 µL: Eppendorf Research
- Micropipette 100 – 1000 µL: Eppendorf Research

SOLUTIONS AND MIXTURES
- Blank: The Diluent was injected as blank sample.
- Diluent: HPLC water and methanol was mixed in 45:55 (V/V) ratio.
- t0 Solution: Approx. 100 mg Urea was weighed with 0.01 mg precision into 10 mL volumetric flask and filled up with Diluent. The solution was mixed well by hand. The concentrations of the urea was approx. 10 mg/mL.
- Stock Solution of Reference Standards: Individual stock solutions were prepared from the selected reference standards. Approx. 10 mg reference compounds were weighed with 0.01 mg precision into 10 mL volumetric flask and filled up with Diluent. The solution was mixed well by hand. The concentrations of the reference substances were approx. 1 mg/mL (cStock).
- Reference Solutions: Reference Solutions (one reference standard per solution) were prepared from the Stock Solutions of Reference Standards to identify the compounds in the Reference Mixture. Calculated volume from the stock solutions (VStock) was pipetted into 10 mL volumetric flask (VMix) and filled up to volume with Diluent. The concentrations of the reference standards in the Reference Solutions referred to as cRefSt.
- Reference Mixture-1 and Reference Mixture-2: Reference Mixture-1 (containing five reference standards in one solution) and Reference Mixture-2 (containing two reference standards in one solution) was prepared from the Stock Solutions of Reference Standards. Calculated volumes from the stock solutions (VStock) were pipetted into 10 mL volumetric flask (VMix) and filled up to volume with Diluent. The concentrations of the reference standards in the Reference Mixture referred to as cRefSt.
- Stock Solution of Test Item: Approx. 10 mg test item was accurately weighted by analytical balance into 10 mL volumetric flask and filled up with Diluent and mixed well by hand.
- Test Item Solution: 100 µL Stock Solution of Test Item was pipetted into 10 mL volumetric flask, filled up to volume with Diluent and mixed well by hand.

HPLC INSTRUMENT PARAMETERS
Instrument: Dionex Ultima 3000 UHPLC with DAD detection
Column: YMC-Pack CN; 2.1x150 mm; S-3 µm, 12 nm
Column temperature: 55°C
Eluent A: Water
Eluent B: Methanol
Flow rate: 0.5 mL/min
Elution: Isocratic, 45:55 A:B
Detection: 210 nm
Run time: 3 min

DETERMINATION OF DEAD-TIME: Urea was injected for the determination of dead-time.

CALIBRATION RESULTS: The reference compounds in the Reference Mixture-1 and Reference Mixture-2 were identified based on the retention times measured in the Reference Solutions. The known logKOC values were figured as a function of calculated log k and a linear calibration curve was fitted.

Key result

Type:

log Koc

Value:

3.22 dimensionless

Remarks on result:

other: Temperature, pH, matrix and % organic carbon not reported

Details on results (HPLC method):

The test item was detected in 1.59 min retention time. The logKOC of the Vetimoss is estimated to be 3.22.

Retention times of the Urea

Component	tR(min)
Urea	0.917
	0.917
	0.917
Average	0.917

Retention times (UV) of the reference compounds

Component	logKOC	tR-UV (min)	k	log k
Acetanilide	1.25	1.070	0.167	-0.778
		1.070	0.167	-0.778
		1.070	0.167	-0.778
Phenol	1.32	1.090	0.189	-0.724
		1.090	0.189	-0.724
		1.087	0.185	-0.732
3,5-Dinitrobenzamide	2.31	1.210	0.320	-0.496
		1.210	0.320	-0.496
		1.210	0.320	-0.496
Naphthalene	2.75	1.480	0.614	-0.212
		1.480	0.614	-0.212
		1.480	0.614	-0.212
1,2,3-trichlorobenzene	3.16	1.663	0.814	-0.090
		1.663	0.814	-0.090
		1.663	0.814	-0.090
Pyrazophos	3.65	1.840	1.007	0.003
		1.840	1.007	0.003
		1.840	1.007	0.003
Phenanthrene	4.09	2.017	1.200	0.079
		2.017	1.200	0.079
		2.017	1.200	0.079

Summary of regression analysis

Summary Table
Regression Statistics
r value	0.9871
r square	0.9744
Corrected r square	0.9731
Standard Error	0.1704
Observations	21
ANOVA
	df	SS	MS	F	F significance
Regression	1	21.012	21.012	723.25	1.380E-16
Resuidual	19	0.5520	0.0291
Sum	20	21.564
	Coefficient	SE	t value	p value	Lower 95%	Upper 95%
Intercept	3.6267	0.0521	69.665	2.357E-24	3.518	3.736
logk	3.0892	0.1149	26.893	1.38E-16	2.849	3.330

 Partition results of the test item

Component	tR(min)	k	logk	logKOC	logKOC- Mean
Vetimoss	1.597	0.742	-0.1299	3.23	3.22
	1.593	0.737	-0.1324	3.22
	1.593	0.737	-0.1324	3.22

Validity criteria fulfilled:

yes

Conclusions:

The logKOC of the Vetimoss is estimated to 3.22.

Executive summary:

The log Koc of Vetimoss was determined using HPLC and according to OECD guideline 121. The Log Koc of Vetimoss was determined to be 3.22.

Description of key information

The log Koc of Vetimoss was determined using HPLC and according to OECD guideline 121. The Log Koc of Vetimoss was determined to be 3.22.

Key value for chemical safety assessment

Koc at 20 °C:

1 660