Hydrocarbon waxes (petroleum), oxidized, Me esters

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:

04 Dec 2017 to 21 Dec 2017

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

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:

no

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Specific details on test material used for the study:

Test facility test item number: 208736/A
Test item storage: At room temperature

Radiolabelling:

no

Test temperature:

35°C +/- 1°C

Details on study design: HPLC method:

PERFORMANCE OF STUDY
The principle of the test method is similar to that of the OECD guideline no. 117: "Partition coefficient (n-octanol/water), high performance liquid chromatography (HPLC) method". While passing through the column along with the mobile phase the test item interacts with the stationary phase. As a result of partitioning between mobile and stationary phases, the test item is retarded. The dual composition of a cyanopropyl stationary phase, having polar and non-polar sites allows for interaction of polar and non-polar groups of a molecule in a similar way as is the case for organic matter in soil or sewage sludge matrices. This enables the relationship between the retention time on the column and the Koc on organic matter to be established.

ANALYTICAL CONDITIONS
Instrument:
Alliance Separation Module 2695
(Waters, Milford, MA, USA)
Detector:
Dual λ Absorbance detector 2487 (Waters)
Column:
Hypersil BDS-CN,
150 mm * 4.6 mm i.d., dp = 5 μm
(Thermo Fisher Scientific, Waltham, MA, USA)
Column temperature:
35°C +/- 1°C
Injection volume:
10 μL
Mobile phase:
75/25 (v/v) THF/buffer pH 7
Flow:
1 mL/min
UV detection:
210 nm

PREPARATION OF SOLUTIONS
Solution of the Unretained Compound:
A 5 g/L stock solution of formamide (99.2%, [75-12-7], Alfa Aesar, Karlsruhe, Germany) in methanol was used. The stock solution was diluted 10-times with 75/25 (v/v) THF/buffer
pH 7. The formamide blank solution was 75/25 (v/v) THF/buffer pH 7.

Reference Substance Solution:
Stock solutions of the reference substances at concentrations of approximately 1 g/L in methanol were used. The stock solutions were diluted to obtain an end solution of 75/25 (v/v) THF/ buffer pH 7. The blank solution for the mixture of reference substances was 75/25 (v/v) THF/ buffer pH 7.

Test Solution:
A 30 g/L stock solution of the test item was prepared in THF. The stock solution was 100-fold diluted with 75/25 (v/v) THF/ buffer pH 7. The final concentration of the test item
solution was 500 mg/L. The test item blank solution was 10% MeOH in 75/25 (v/v) THF/ buffer pH 7.

REFERENCE SUBSTANCES
See Table 2 attached.

SAMPLE INJECTIONS
Reference substance and test item solutions were injected in duplicate. Blank solutions were analyzed by single injection.

Analytical monitoring:

yes

Details on sampling:

Reference substance and test item solutions were injected in duplicate. Blank solutions were analyzed by single injection.

Computational methods:

System name: Empower 3
Version No. 7.21
Description of Data Collected and/or Analyzed: System control, data acquisition and integration

System: REES Centron
Version No. SQL 2.0
Description of Data Collected and/or Analyzed: Temperature, relative humidity and/or atmospheric pressure monitoring

Key result

Sample No.:

#1

Type:

log Koc

pH:

7

Temp.:

35 °C

Remarks on result:

not determinable

Details on results (HPLC method):

The test item was barely soluble in acetonitrile or methanol. Tetrahydrofuran was found to be the most suitable to dissolve the test item. Dilution solvents containing 55/45 (v/v) MeOH/phosphate buffer pH 7, 55/45 (v/v) THF/buffer pH 7 and 75/25 (v/v) THF/phosphate buffer at pH 7 were tested. Solution of 75/25 (v/v) THF/ buffer at pH 7 was found to be the most suitable.

The detection with RI and UV detectors was tested. The sufficient signal response under these conditions was observed at the concentrations above 300 mg/L with UV detection. HPLC-UV chromatograms of the test item solution and corresponding blank are shown in Figure 1 and Figure 2 (see attached), respectively. A test item is a substance of unknown variable composition (UVCB), which was confirmed with broad distribution seen in the chromatogram.

Due to the strong elution solvent the reference substance solutions under the same analytical conditions were unretained. The chromatographic elution of the acetanilide (log Koc = 1.26)
and 4,4’-DDT (log Koc = 5.63) and of the unretained compound (formamide) are shown in Figure 3 (see attached).

Mentioned above results drive to conclusion that the estimation of the Adsorption Coefficient (Koc) of the test item cannot be performed.

Validity criteria fulfilled:

not applicable

Conclusions:

The HPLC method using soil-adsorption-reference data was applied for the determination of the adsorption coefficient (Koc) of the test item. Due to the properties of the test item and strong elution conditions for the analysis, the estimation of the adsorption coefficient was technically not possible.

Executive summary:

GUIDELINE

The determination was carried out using the HPLC screening method and was designed to be compatible with OECD 121 (22 January 2001) and EU Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 (30 May 2008). The test system utilised a High Performance Liquid Chromatograph (HPLC). A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used.

RESULTS

The test item was barely soluble in acetonitrile or methanol. Tetrahydrofuran was found to be the most suitable to dissolve the test item. Dilution solvents containing 55/45 (v/v) MeOH/phosphate buffer pH 7, 55/45 (v/v) THF/buffer pH 7 and 75/25 (v/v) THF/phosphate buffer at pH 7 were tested. Solution of 75/25 (v/v) THF/ buffer at pH 7 was found to be the most suitable. The detection with RI and UV detectors was tested. The sufficient signal response under these conditions was observed at the concentrations above 300 mg/L with UV detection. Due to the strong elution solvent the reference substance solutions under the same analytical conditions were unretained. The chromatographic elution of the acetanilide (log Koc = 1.26) and 4,4’-DDT (log Koc = 5.63) and of the unretained compound (formamide) were reported. The results drive to conclusion that the estimation of the Adsorption Coefficient (Koc) of the test item cannot be performed.

CONCLUSION

The HPLC method using soil-adsorption-reference data was applied for the determination of the adsorption coefficient (Koc) of the test item. Due to the properties of the test item and strong elution conditions for the analysis, the estimation of the adsorption coefficient was technically not possible.

Description of key information

Due to the properties of the test item and strong elution conditions for the analysis, the estimation of the adsorption coefficient was technically not possible.

Additional information

GUIDELINE

The determination was carried out using the HPLC screening method and was designed to be compatible with OECD 121 (22 January 2001) and EU Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 (30 May 2008). The test system utilised a High Performance Liquid Chromatograph (HPLC). A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used.

RESULTS

The test item was barely soluble in acetonitrile or methanol. Tetrahydrofuran was found to be the most suitable to dissolve the test item. Dilution solvents containing 55/45 (v/v) MeOH/phosphate buffer pH 7, 55/45 (v/v) THF/buffer pH 7 and 75/25 (v/v) THF/phosphate buffer at pH 7 were tested. Solution of 75/25 (v/v) THF/ buffer at pH 7 was found to be the most suitable. The detection with RI and UV detectors was tested. The sufficient signal response under these conditions was observed at the concentrations above 300 mg/L with UV detection. Due to the strong elution solvent the reference substance solutions under the same analytical conditions were unretained. The chromatographic elution of the acetanilide (log Koc = 1.26) and 4,4’-DDT (log Koc = 5.63) and of the unretained compound (formamide) were reported. The results drive to conclusion that the estimation of the Adsorption Coefficient (Koc) of the test item cannot be performed.

CONCLUSION

The HPLC method using soil-adsorption-reference data was applied for the determination of the adsorption coefficient (Koc) of the test item. Due to the properties of the test item and strong elution conditions for the analysis, the estimation of the adsorption coefficient was technically not possible.