Paraffin waxes (Fischer-Tropsch), isomerization

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:

03 and 08 June 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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:

no

GLP compliance:

yes

Remarks:

The work described was performed in compliance with UK GLP standards (Schedule 1, Good Laboratory Practice Regulations 1999 (SI 1999/3106 as amended by SI 2004/0994)).

Type of method:

HPLC estimation method

Media:

sewage sludge

Radiolabelling:

no

Test temperature:

Column temperature = 40.0 ºC

Details on study design: HPLC method:

EQUIPMENT
- Apparatus:
- Type: Agilent Technologies 1100, incorporating autosampler and workstation
- Type, material and dimension of analytical (guard) column: Genesis CN 120Å (250 x 4.6 mm id)
- Detection system: Refractive index


MOBILE PHASES
- Type: tetrahydrofuran:water (55:45 v/v)
- Experiments with additives carried out on separate columns: no
- pH: 7.0, adjusted using 0.1 m sodium hydroxide
- Solutes for dissolving test and reference substances: tetrahydrofuran


DETERMINATION OF DEAD TIME
- Method: by means of homologous series / by inert substances which are not retained by the column
The dead time was determined by measuring the retention time of formamide

REFERENCE SUBSTANCES
- Identity: Acetanilide, Phenol, Atrazine, Isoproturon, Triadimenol, Linuron, Naphthalene, Endosulfan-diol, Fenthion, -Endosulfan, Phenanthrene , Diclofop-methyl and DDT


DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 0.5070 g
- Quantity of reference substances:
- Intervals of calibration:


REPETITIONS
- Number of determinations: 2


EVALUATION
- Calculation of capacity factors k': >2.22
- Calculation of retention times: >9.5
- Determination of the log Koc value: >5.63

Type:

Koc

Value:

> 427

Type:

log Koc

Value:

> 5.63

Details on results (HPLC method):

- Retention times of reference substances used for calibration:
- Details of fitted regression line (log k' vs. log Koc):
- Graph of regression line attached
- Average retention data for test substance:

A calibration curve was created using the following results as reference standards:

Dead Time	Retention Time (mins)		Mean Retention Time (mins)
	Injection 1	Injection 2
Formamide	2.947	2.949	2.948

Standard	Retention Time (mins)		Mean Retention Time (mins)	Capacity Factor (k)	Log10k	Log10 Koc
	Injection 1	Injection 2
Acetanilide	3.754	3.753	3.754	0.237	-0.563	1.25
Phenol	4.215	4.218	4.217	0.430	-0.366	1.32
Atrazine	4.612	4.616	4.614	0.565	-0.248	1.81
Isoproturon	4.198	4.199	4.199	0.424	-0.372	1.86
Triadimenol	4.694	4.690	4.692	0.592	-0.228	2.40
Linuron	4.635	4.645	4.640	0.574	-0.241	2.59
Naphthalene	5.263	5.263	5.263	0.785	-0.105	2.75
Endosulfan-diol	4.981	4.985	4.983	0.690	-0.161	3.02
Fenthion	5.537	5.542	5.540	0.879	-5.60 x 10^-2	3.31
a-Endosulfan	6.948	6.947	6.948	1.36	0.132	4.09
Phenanthrene	5.604	5.601	5.603	0.900	-4.55 x 10^-2	4.09
Diclofop-methyl	6.325	6.322	6.324	1.15	5.88 x 10^-2	4.20
DDT	7.954	7.946	7.950	1.70	0.230	5.63

The retention times, capacity factors and log₁₀K_ocvalues determined for the sample are shown in the following table:

Injection	Retention Time (mins)	Capacity Factor (k)	Log10k	Log10Koc
1	>9.5	>2.22	>0.347	>5.63
2	>9.5	>2.22	>0.347	>5.63

Mean log₁₀K_oc:                       >5.63
Adsorption coefficient: >4.27 x 10⁵

Validity criteria fulfilled:

yes

Conclusions:

adsorption coefficient (Koc): >4.27 x 10E5, log10 Koc >5.63

Executive summary:

The determination was carried out for the substance GTL waxy raffinate [C15-50; CAS 848301-87-1, EC 482-130] using the HPLC screening method, Method C.19 of Commission Directive 2001/59/EC (which constitutes Annex V of Council Directive 67/548/EEC).

The adsorption coefficient (Koc) of the test material has been determined to be > 4.27 x 10⁵, log₁₀ Koc > 5.63.

Description of key information

- Estimated log K_OC at 25 °C of the closely related substance GTL waxy raffinate [C15-50; CAS 848301-87-1, EC 482-130] covering the low molecular weight fraction of the registration substance up to C50 [determined using EU Method C.19, HPLC method; GLP]: log₁₀ K_OC >5.63;

- Based on the fact that the experimentally determined value for GTL waxy raffinate is based on the highest calibration standard [DDT, limit value of 5.63], it can be safely concluded that the result for the registration substance 'Paraffin waxes (Fischer-Tropsch), isomerization' containing higher molecular weight constituents (C25-150, about 30-55 % >C50) would be the same: log₁₀ K_OC >5.63;

- The conclusion is supported by the identical test result for the closely related substance GTL base oil (CAS 848301-69-9, EC 482-220-0), which consists of linear and branched alkanes (paraffins) with a small amount of cycloalkanes in the carbon range from C18 to C50;

- The high adsorption coefficient indicates that constituents of these UVCB substances will have high likelihood of partitioning to sediments, organic matter in soil or sludge in the sewer system.

Additional information

Measured data are not available for the registration substance 'Paraffin waxes (Fischer-Tropsch), isomerization'.

However, reliable data of the closely related substance GTL waxy raffinate (CAS 848301-87-1, EC 482-130-1) can be used to address the endpoint, which is suitable to draw conclusions on the adsorption coefficient of the registration substance.
The test item GTL waxy raffinate - consisting of linear and branched alkanes (paraffins) in the carbon range from C15 to C50 - covers the low molecular weight fraction of the registration substance.

Based on the fact that the experimentally determined value of this closely related substance is based on the highest calibration standard [DDT, limit value of 5.63], it can be safely concluded that the experimental result for the registration substance containing higher molecular weight constituents (C25-150, about 30-55 % >C50) would be the same: greater than 4.27 x 10⁵, log₁₀ K_OC >5.63.

The conclusion is supported by the identical test result for the closely related substance GTL base oil (CAS 848301-69-9, EC 482-220-0), which consists of linear and branched alkanes (paraffins) with a small amount of cycloalkanes in the carbon range from C18 to C50; see supporting study).

The high adsorption coefficient indicates that constituents of these UVCB substances will have high likelihood of partitioning to sediments, organic matter in soil or sludge in the sewer system.