Cyclohexyldimethylammonium dihydrogen phosphate

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

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:

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:

May 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Radiolabelling:

no

Test temperature:

25 °C (HPLC column temperature)

Details on study design: HPLC method:

EQUIPMENT
- Apparatus:
- Type: Agilent 1200 Series Liquid Chromatograph
- Type, material and dimension of analytical (guard) column: HyperClone 5µ CN (CPS) (25 cm x 4.6 mm internal diameter)
- Detection system: UV set at 210 nm

MOBILE PHASES
- Type: Acetonitrile:buffer solution (55:45 v/v), where a phosphate buffer solution was employed for the pH 4 test and a borate buffer solution for the pH 9 test
- Experiments with additives carried out on separate columns: no additives used
- pH: 4 and 9
- Solutes for dissolving test and reference substances: mobile phase

DETERMINATION OF DEAD TIME
- Method: by inert substances which are not retained by the column (formamide, retention time ca. 3 min)

REFERENCE SUBSTANCES
- Identity: Acetanilide, Nitrobenzene, Naphthalene, 2-Methylnaphthalene, Anthracene, DDT
- Known logKoc values: 1.3, 2.4, 2.8, 3.9, 4.4, 5.6

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 100 µg
- Quantity of reference substances:
Formamide (internal deadtime standard): 4 µg, Acetanilide: 0.2 µg, Nitrobenzene: 0.2 µg, Naphthalene: 0.06 µg, 2-Methylnaphthalene: 0.06 µg, Anthracene: 0.2 µg, DDT: 0.2 µg
- Intervals of calibration: before and after injections of the test substance

REPETITIONS
- Number of determinations: two

EVALUATION
- Determination of the log Koc value: A calibration plot of log10k versus log10Koc was constructed for the reference standards. The logarithms of the capacity factors for the test substance were calculated and the log10Koc values were determined by interpolation or extrapolation, as appropriate.

Analytical monitoring:

not required

Key result

Type:

log Koc

Value:

< 1.3 dimensionless

pH:

4

Temp.:

25 °C

Key result

Type:

log Koc

Value:

> 5.6 dimensionless

pH:

9

Temp.:

25 °C

Details on results (HPLC method):

pH 4 test
- Retention times of reference substances used for calibration: acetanilide 3.40 min, nitrobenzene 3.94 min, naphthalene 4.48 min, 2-methylnaphthalene 4.73 min, anthracene 5.19 min, DDT 7.30 min
- Details of fitted regression line: log10Koc = 4.83 log10k + 4.64
- Graph of regression line attached
- Average retention data for test substance: 3 min (with dead-time) for the amine component, 3.53 min for the phosphate counter-ion
The amine component of the test substance was found to have a retention time less than that of the lowest reference standard, acetanilide. It co-eluted with the deadtime standard, as indicated by an enhanced response of this peak versus that in the standard chromatogram (approximately 660 versus 610 area units). Its presence was also indicated by analysis of the more concentrated stock solution. The amine component chromatographed as a very broad peak in this injection matrix, but with an onset at the approximate retention time of the deadtime standard.

pH 9 test:
- Retention times of reference substances used for calibration: acetanilide 3.12 min, nitrobenzene 3.39 min, naphthalene 3.69 min, 2-methylnaphthalene 3.83 min, anthracene 4.11 min, DDT 5.30 min
- Details of fitted regression line: log10Koc = 3.32 log10k + 5.65
- Graph of regression line attached
- Average retention data for test substance: 8.69 min for the amine component, 3.18 min for the phosphate counter-ion
The amine component of the test substance was found to have a retention time greater than that of the highest reference standard, DDT.

The phosphate counter-ion at approximately 3.2 minutes was determined to have a log10Koc value of 1.5 at both pH-values.

Validity criteria fulfilled:

not applicable

Description of key information

Log Koc at 25°C (HPLC method): < 1.3 at pH 4, > 5.6 at pH 9, (OECD 121, EU C.19)

 

Additional information

Log Koc at 25 °C: < 1.3 at pH 4, > 5.6 at pH 9