4,8-dicyclohexyl-6-hydroxy-2,10-dimethyl-12H-dibenzo[d,g][1,3,2]dioxaphosphocin

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:

2016-08-18 - 2016-10-28

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 Guideline for Testing of Chemicals No. Guideline No.121: ”Estimation of the Adsorption Coefficient on Soil and on Sewage sludge using High Performance Liquid Chromatography (HPLC)”,
adopted 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:

Commission Regulation (EC) No.440/2008, Annex, C.19: “Estimation of the Adsorption Coefficient 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: n/a

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At 4°C ± 4°C , in the dark

Radiolabelling:

no

Test temperature:

25°C

Details on study design: HPLC method:

EQUIPMENT
- Apparatus: A high performance liquid chromatograph with an UV-VIS detector or MS detector was used. The detection wavelength or MS conditions depended on the characteristics of the test item and the reference items.
- Type, material and dimension of analytical (guard) column: The stationary phase was a cyanopropyl phase.
- Detection system:
HPLC-Conditions:
Column: LiChrospher 100 CN (250*4 mm, 5 μm)
Eluent: 55% methanol / 45% pure water
Flow: 1.0 mL/min
Injection Volume: 5 μL
Temperature: 25 °C
UV-Detector: 205 nm

LC-MS-Conditions:
Column: LiChrospher 100 CN (250*4 mm, 5 μm)
Eluent: 55% methanol / 45% pure water
Flow: 1.0 mL/min
Injection Volume: 5 or 20 μL
Temperature: 25°C
MS-Detector: API3200
Turbo Spray
CUR: 20; Tem: 450; IS: ± 4500; DP: ± 45; EP: ± 10
Nitrate: Q1 Scan 50 to 100 amu, negative
Acetanilide: Q1 Scan 50 to 200 amu, positive
Test item: MRM, positive
439 amu to 275 amu, 439 amu to 357 amu

MOBILE PHASES
- Type: The mobile phase was 55% methanol / 45% pure water
- Experiments with additives carried out on separate columns: no
- Solutes for dissolving test and reference substances: A stock solution of the test item was prepared by dissolution in methanol. 50.26 mg of the test item were weighed, dissolved and made up to 50 mL.
A stock solution of each reference compound was prepared by dissolution of the reference item in methanol.

DETERMINATION OF DEAD TIME
- Method: Sodium nitrate was used as inert substance (not retained by the column) to determine the dead time. A stock solution of the compound was prepared by dissolution in pure water (1000 mg/L). This stock solution was diluted with solvent mixture of methanol/pure water (55%:45%, v:v) and was injected to determine the dead time t0 (t0 = retention time of the unretarded component).

REFERENCE SUBSTANCES
Six chemicals for which log Koc has been reported were used to calibrate the elution time in units of log Koc. Structurally heterogeneous reference items were chosen.
- Identity:
Reference Item Supplier Batch No. Purity [%] log Koc
Acetanilid VWR 10182588 99.9 1.25
Methylbenzoat Merck KGaA S4946930 99.9 1.80
Linuron Labor Dr. Ehrenstorfer 10418 99.5 2.59
1,2,3 Trichlorobenzene Labor Dr. Ehrenstorfer 10322 99.5 3.16
Pyrazophos VWR SZBD304XV 99.8 3.65
Diclofop-methyl VWR 40110 98.5 4.20
Sodium nitrate VWR 13B 120033 99.6 -

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: For application the stock solution was diluted in solvent mixture of methanol/pure water (55%:45%, v:v) to obtain standard solutions at the concentration of 10 mg/L and 100 mg/L.
- Quantity of reference substances: Appropriate volumes of the stock solutions were diluted using solvent mixture of methanol/pure water (55%:45%, v:v) to prepare standard solutions of these compounds at concentration of 50 mg/L. In addition, defined volumes of each of the stock solutions were diluted to prepare a reference item mixture.
The reference compound Acetanilide was diluted in solvent mixture of methanol/pure water (55%:45%, v:v) to obtain standard solution at the concentration of 10 mg/L used in LC-MS analysis.
- Intervals of calibration:

REPETITIONS
- Number of determinations: 3 replicates

EVALUATION
Result Evaluation
Calculations: In this study the adsorption coefficient Koc is deduced from the capacity factor k’ using a calibration plot of log k’ versus log Koc of selected reference items.
The capacity factor was calculated from the retention of the substance concerned (tr) and the unretarded component (t0):
k' = (tr - t0) / t0
where:
tr = retention time of the test item [min]
t0 = time a non-sorbed chemical needs to pass the column (dead time) [min]
k' = capacity factor
Rounding of Decimal Places: All calculations are performed by computer or electronic calculator with varying degrees of soft- and hardware dependent floating point precision. Numerical values are frequently rounded to a smaller degree of precision (number of digits).

Key result

Type:

log Koc

Value:

> 4.2 dimensionless

Temp.:

25 °C

Details on results (HPLC method):

- Retention times of reference substances used for calibration:
HPLC-UV-determination
Item Number of analysis Retention Time [min]* Capacity Factor1 log k'1 log KOC2
Sodium nitrate (=dead time) HPLC 3 1.23 n.a. n.a. n.a.
Sodium nitrate (=dead time) LCMS 3 1.35 n.a. n.a. n.a.
Reference Items:
Acetanilid 3 3.21 1.60 0.20 1.25
Methylbenzoat 3 3.65 1.97 0.29 1.80
Linuron 3 4.61 2.74 0.44 2.59
1,2,3 Trichlorobenzene 3 5.00 3.06 0.49 3.16
Pyrazophos 3 5.96 3.84 0.58 3.65
Diclofop-methyl 3 6.87 4.58 0.66 4.20

n.a. not applicable
1 values represent rounded results calculated from the exact raw data
2 log Koc values as given in the reference
* mean value of three measurements

- Details of fitted regression line (log k' vs. log Koc):
Calibration: The adsorption coefficient Koc was determined based on a calibration curve using 6 reference items. The calibration curve was obtained from data generated by HPLC-UV detection.
Calibration curve: y = 0.1535* x – 0.0184, regression coefficient r² = 0.9940
Linearity: The linearity of the method was proven in the log Koc-range from 1.25 to 4.20.
- Average retention data for test substance: 21.539 min

Validity criteria fulfilled:

yes

Conclusions:

The study was conducted under GLP according OECD TG 121 and is assessed with Klimisch 1. Hence, the results can be considered as sufficiently reliable to assess the absorption / desorption behaviour and to measure the Koc / logKoc of the test item. Based on the retention times of Nitrate and the test item and based on the calibration curve obtained by HPLC analysis, the capacity factor and LogKoc of the test item was calculated as Log Koc (estimated): >> 4.2. Based on the measured results, the actual logKoc was calculated as 7.8 resp. 6.8. However, as this value is out of the linearity range of the calibration curve, the logKoc is stated as >4.2 (highest logKoc of the reference items used).

Executive summary:

The Adsorption Coefficient (Koc) of 4,8-dicyclohexyl-2,10-dimethyl-12H-dibenzo[d,g][1,3,2] dioxaphosphocin-6-ol was estimated by the HPLC method [OECD 121] under GLP.

The purpose of the study was to estimate the adsorption coefficient Koc of the test item using HPLC-method. The measured retention time of the test item was correlated with its adsorption coefficient using a calibration graph. The test setup was a HPLC with UV and MS detection was used for estimation of the adsorption coefficient Koc.

Results: The present study estimated the log Koc of the test item using HPLC method. Based on calibration curves obtained by correlation of the retention time of 6 structurally heterogeneous reference items with their known adsorption coefficient, the log Koc of the test was estimated to be above 4.2.

Description of key information

Adsorption / desorption screening: LogKoc > 4.2 (HPLC method, OECD 121, GLP)

Key value for chemical safety assessment

Koc at 20 °C:

15 849

Additional information

[LogKoc: 4.2]