1,4-Benzenediol, 2-(6-oxido-6H-dibenz[c,e][1,2]oxaphosphorin-6-yl)-

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 -May 2020

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))

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Radiolabelling:

no

Test temperature:

Room temperature

Details on study design: HPLC method:

Pre-Test
In a non GLP pre- test, a solution of the test item with a concentration of 68.75 mg/L was
injected in order to check retention time and the signal height. The solution gave one high
peak at 3.192 minutes.
Based on this result, a suitable mix of reference items was chosen (with 4,4´-DDT as substance
with the highest log KOC and a retention time of approx. 26.6 minutes).
The test item solution was diluted to 27.5 mg/L for the determination of the log KOC of the
test item, in the main test.

Determination of the Dead Time
The dead time t0 was measured by using an unretained compound (sodium nitrate) which
was included in the mix of the reference items.

Determination of the Log KOC of the Test Item
One vial was filled with solvent blank (methanol/water 55/45 % v/v), one vial with the reference
item mix and one vial with the test item solution. The vials were analysed using HPLC
with the program described in chapter 6.4.2. One injection was measured from the solvent
blank, three injections from the reference item mix, three injections from the test item solution
and again three injections from the reference item mix.
The data was saved, the retention times of the seven peaks of the reference item mix and
the retention time of the peak of the test item were used for further calculations.

HPLC_6 (HPLC Ultimate3000)
Components: Solvent Rack
Pump LPG-3400SD
Autosampler WPS-3000TSL
Column Compartment TCC-3200 with 6-fold column switch valve
UV-Detector MWD-3000
Manufacturer: Thermo Fisher Scientific
Software: CHROMELEON 6.80 SR15b Build 4981
Usage and calibration followed the corresponding SOP 114 005 29 in the current edition.

Instrument Parameters
Eluents: MeOH/H2O 55/45 (% v/v), ultrasonic and vacuum degassed
Flow rate: 0.8 mL/min
Injection volume: 10 μL
Column: Reprosil Pur CN 150*4.6 mm, 3 μm with guard column
Phenomenex SecurityGuard CN, 4*3 mm
Column temperature: 25 ± 0.5 °C
Wavelength for evaluation: 210 nm (reference item mix)
245 nm (test item)

Key result

Sample No.:

#1

Type:

log Koc

Value:

1.73 dimensionless

Remarks on result:

other: Mean value of three measurments

Details on results (HPLC method):

- Retention times of reference substances used for calibration:
- Details of fitted regression line (log k' vs. log Koc):
Table – Log k’ and log KOC of Reference Items
Compound log k’ log KOC
Acetanilide 0.204 1.25
Methylbenzoate 0.318 1.80
Naphthalene 0.577 2.75
1,2,3-Trichlorobenzene 0.689 3.16
Phenanthrene 0.880 4.09
4,4‘-DDT 1.378 5.63

- Graph of regression line attached


- Average retention data for test substance:
Table– Retention Times (RT) Test Item
Peak 1 Test Item RT
min
Measurement 1 3.237
Measurement 2 3.237
Measurement 3 3.237
Mean 3.237
Standard deviation 0.000

Validity criteria fulfilled:

yes

Conclusions:

Variations in the retention times of reference items and test item are very small. Therefore,
a stable configuration of the HPLC-column can be assumed.
The correlation log k’/log KOC is good: the coefficient of determination r2 was calculated with
0.9947. This value was considered as sufficiently high to use the calibration function for the
determination of the log KOC of the test item 10-(2,5-Dihydroxyphenyl)-10H-9-oxa-10-
phospha-phenantbrene-10-oxide (DOPO-Hydroquinone).
The test item 10-(2,5-Dihydroxyphenyl)-10H-9-oxa-10-phospha-phenantbrene-10-oxide
(DOPO-Hydroquinone) gave one peak with a retention time of 3.237 min (mean).
Using the correlation log k’ / log KOC, the log KOC of the peak of the test item 10-(2,5-
Dihydroxyphenyl)-10H-9-oxa-10-phospha-phenantbrene-10-oxide (DOPO-Hydroquinone)
was calculated as 1.73 ± 0.00 (mean ± standard deviation).
No observations were made which might give doubts concerning the validity of the study
outcome.

Description of key information

Log Koc measured by HPLC method, due to instability of the substance in water.

LogKoc=1.73

Key value for chemical safety assessment

Koc at 20 °C:

53.7