1,6-Bis(methoxybenzoyloxy)hexane

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:

March 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to OECD test methd and to GLP standards

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:

yes

Remarks:

For calculation of pKa values from the structural formula, different hardware and a previous version of the software were used. Results and therefore study integrity were not affected by this deviation.

Principles of method if other than guideline:

For calculation of pKa values from the structural formula, different hardware and a previous version of the software were used. Results and therefore study integrity were not affected by this deviation.

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Radiolabelling:

no

Test temperature:

A temperature controlled column compartment at 35°C was used.

Details on study design: HPLC method:

A High Performance Liquid Chromatograph with a spectrophotometric detector was used. The stationary phase was a cyanopropyl chemically bound resin on silica basis (Hypersil BDS-CN). The mobile phase was 55/45 (v/v) methanol/water. A temperature controlled column compartment at 35°C was used.

Reagents
Methanol HPLC-grade, Labscan, Dublin, Ireland
Acetonitrile HPLC-grade, Labscan, Dublin, Ireland
Milli-Q water Tap water purified by reversed osmosis and subsequently passed over activated carbon and ionexchange cartridges; Millipore, Bedford, MA, USA
Formamide >/=99.5%, Acros Organics, Geel, Belgium

Refrence substances (with log Koc Values)

Phenol (99%, Acros organics, Geel, Belgium) 1.32
N,N-dimethylbenzamide (98%, Acros organics, Geel, Belgium) 1.52
Methylbenzoate (99%, Acros organics, Geel, Belgium) 1.80
3,5-Dinitrobenzamide (97%, .Acros organics, Geel, Belgium) 2.31
Naphtalene (99%, Acros organics, Geel, Belgium) 2.75
Mercaptodimethur (98.5%, Dr. Ehrenstorfer, Augsburg, 3.10
Germany)
Fenthion (96%, Riedel-de Ha1en, Seelze, Germany) 3.31
Phenantrene (>98%, Acros organics, Geel, Belgium) 4.09
2,4-DDT (97%, Dr. Ehrensto1fer, Augsburg, Germany) 5.63

Analytical conditions
Column Hypersil BDS-CN; 150 x 4.6 (l.D.) mm; dμ= 5 μm (Alltech, Deerfield, IL, USA)
Column temperature 35 °C
Mobile phase 55/45 (v/v) methanol/Milli-Q water
Flow 1 ml/min
Detection UV at J..= 210 nm
Injection volume 10 μI

Preparation of the solutions

Solutions of the reference substances in methanol, at concentrations between 0.99 and 6.4 g/I, were used. From these solutions, two mixtures of reference substances were prepared. One mixture contained 5 reference substances and was prepared by adding 50 μI of each reference substance solution to a volumetric 5 ml flask. The other mixture contained 4 reference substances and was prepared by adding 50 μI of each reference substance solution and 50 μI methanol to a volumetric 5 ml ·flask. Subsequently, the flasks were filled up to the mark with mobile phase. As reference blank solutions, 95/5 (v/v) mobile phase/methanol was used.
A 5.4 g/I solution of formamide~ in methanol was diluted by a factor 10 with mobile phase. This solution was used for the determination of to (retention time of the unretarded component). As blank formamide solution, 90/10 (v/v) mobile phase/methanol was used.
A 1.1 g/I stock solution of Seta1fix X 11342 was prepared in acetonitrile. In order to dissolve the test substance completely, this solution was ultrasonicated for 5 minutes. The test solution was prepared by diluting the stock solution by a factor 100 with mobile phase. As blank solution 99/1 (v/v) mobile phase/acetronitrile was used.

Injections
The solutions were injected in the following sequence: mobile phase, the mixtures 1 and 2 of reference substances, the reforence blank solution, the formamide solution, the formamide blank solution, the test solution (in duplicate), the corresponding blank solution, the mixtures 1 and 2 of reference substances and the formamide solution. The chromatograms were recorded for 10 minutes, except for the 'formamide solution and the formamide blank solution which were recorded for 5 minutes.

Type:

Koc

Value:

50 000 dimensionless

Temp.:

35 °C

Details on results (HPLC method):

Calculation of pKa values
According to pKa calculations using a computer calculation program, the test substance does not contain ionizable groups. Therefore, the mobile phase was not buffered during the performance of the test.
Determination of Koc
In the HPLC chromatograms of Setafix X 11342, using detection at 210 nm, one large and seven small test substance peaks were observed. It was assumed that the large peak derives from the major component of test substance whereas the small peaks derive from impurities.
The ‘t0’ was determined to be 1.925 minutes as a mean value of both measurements (i.e. 1.923 and 1.926 minutes).
The mean values of the retention times, k’ values, log k’ values, log Koc and Koc values are summarized below.

tr k' log k' log Koc
Reference substance
Phenol 2.281 0.185 -0.732 1.32
N,N-dimethylbenzamide 2.135 0.109 -0.961 1.52
Methylbenzoate 2.442 0.269 -0.570 1.80
3,5-Dinitrobenzamide 2.615 0.359 -0.445 2.31
Naphtalene 3.111 0.617 -0.210 2.75
Mercaptodimethur 2.928 0.521 -0.283 3.10
Fenthion 4.449 1.312 0.118 3.31
Phenantrene 4.358 1.264 0.102 4.09
2,4-DDT 7.134 2.707 0.432 5.63

tr k' log k' log Koc Koc Area%
Test substance
Peak 1 1.317 -0.316 - <1.32 <21 0.5
Peak 2 2.778 0.443 -0.353 2.64 440 1.2
Peak 3 3.230 0.678 -0.169 3.24 1800 0.5
Peak4 3.387 0.760 -0.119 3.40 2500 0.8
Peak 5 3.757 0.952 -0.021 3.72 5300 0.2
Peak 6 4.664 1.423 0.153 4.29 20000 0.3
Peak 7 (major) 5.586 1.903 0.279 4.70 50000 95.1
Peak 8 6.816 2.542 0.405 5.11 130000 1.4

For seven impurities, the adsorption coefficient (Koc) was determined to be:

<21 (log Koc <1.32), 440 (log Koc= 2.64), 1800 (log Koc= 3.24 ), 2500 (log Koc= 3.40),

5300 (log Koc= 3.72), 20000 (log Koc= 4.29) and 130000 (log Koc= 5.11) at 35°C.

Conclusions:

The adsorption coefficient (Koc:) of Setafix X 11342 was determined to be 50000 (log Koc= 4. 70) at 35°C.

Executive summary:

The adsorption coefficient (Koc:) of Setafix X 11342 was determined to be 50000 (log Koc= 4. 70) at 35°C.

Description of key information

The adsorption coefficient (Koc:) of Setafix X 11342 was determined to be 50000 (log Koc= 4. 70) at 35°C.