3,20-bis(ethylenedioxy)pregna-5,7-diene

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18 December 2012 to 12 March 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: In accordance with OECD method and GLP, substance well characterised.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

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:

During method validation the stability of analytical system & end solutions at 0.04 mg/L didn't meet requirements . Evaluation: calibration should be checked frequently during subsequent analyses at this level;study integrity wasnt adversely affected.

Test guideline 2

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))

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Test material

Test material information

Constituent 1

Reference substance name:

3,20-bis(ethylenedioxy)pregna-5,7-diene

EC Number:

243-175-0

EC Name:

3,20-bis(ethylenedioxy)pregna-5,7-diene

Cas Number:

19592-55-3

Molecular formula:

C25H36O4

IUPAC Name:

(1S,3aR,9aR,9bS,11aS)-9a,11a-dimethyl-1-(2-methyl-1,3-dioxolan-2-yl)-1,2,3,3a,6,8,9,9a,9b,10,11,11a-dodecahydrospiro[cyclopenta[a]phenanthrene-7,2'-[1,3]dioxolane]

Test material form:

solid: crystalline

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Batch 0385
Purity/Composition 95.9%

Radiolabelling:

no

Study design

HPLC method

Details on study design: HPLC method:

Analytical conditions

Instrument Acquity UPLC system (Waters, Milford, MA, USA) Detector
Acquity UPLC PDA detector (Waters)Column ,
Acquity UPLC HSS Cyano column, 100 x 2.1 (i.d.) mm, dp =1.8 µm.
Column temperature 35°C +- 1°C
Mobile phase 55/45 (v/v) methanol/water
Flow 0.4 mL/min
Injection volume 5 µL
UV detection 210 nm

A 470 mg/L stock solution of the test substance was prepared in methanol. In order to dissolve the test substance the stock solution was ultrasonicated for 20 minutes. The stock solution was diluted to obtain an end solution of 55/45 (v/v) methanol/water. The final concentration of the test substance solution was 6.016 mg/L.

The test substance blank solution was 55/45 (v/v) methanol/water.
The reference substance and test substance solutions were injected in duplicate. Blank solutions were analysed by single injection.

Batch equilibrium or other method

Computational methods:

Calculation of pKa values: No pKa values were calculated in the logarithm range of 1 – 14 using the Perrin calculation method.
Determination of the Koc: The results of the HPLC method are given in the Table 8. Figure 12 shows the calibration curve of the log k’ of the reference substances as function of log Koc. The equation of the regression line was: log k’ = 0.3179  log Koc – 0.812 (r = 0.98, n = 12).

Results and discussion

Adsorption coefficient

Adsorption coefficient 1

Type:

log Koc

Value:

5.31

Remarks on result:

other: at neutral PH

Adsorption coefficient 2

Type:

Koc

Value:

200 000

Remarks on result:

other: at neutral pH

Results: HPLC method

Details on results (HPLC method):

According to the guidelines, the determination of the Koc for test substances that are ionized for at least 10% within pH 5.5 to 7.5 should be performed with both the ionized and non-ionized form. Therefore, the pKa values of the test substance were calculated using the Perrin calculation method (pKalc 5.0, module in Pallas 3.0, CompuDrug International San Francisco, CA, USA). Based on the calculations, the HPLC analysis was performed at neutral pH.

The test substance is a salt. These types of compounds are ionized in solution at each pH value. The HPLC analysis was therefore only performed at neutral pH. Calculations on the pKa values using the Perrin calculation method were not performed. Solutions of reference substances with known log Koc values based on soil adsorption data and the test substance were analysed. The capacity factor (k') of each compound was calculated from its retention time. The log k’ values of the references substances were plotted against the known log Koc values. A linear regression program was used to calculate the calibration curve. Linear regression analysis was performed using the least squares method. The coefficient of correlation (r) was calculated. The log Koc value for the test substance was calculated by substituting its mean log k’ in the calibration curve. The value of log Koc obtained from duplicate measurements was within  0.25 log units.

Any other information on results incl. tables

The results of the HPLC method are given below. The equation of the regression line was :log k’=0.3179´logKoc– 0.812(r=0.98, n =12).

Koc of the test substance

 

Substance	tr,1 [min]	tr,2 [min]	meantr (n=2)	logKoc	Koc	Area %
Formamide(t0) Acetanilide Monuron Benzoicacid phenylester Fenthion Phenanthrene 4,4’-DDT TS204476-Peak1	0.650  0.857 1.053   1.637   2.192 2.425 6.041   5.513	0.647  0.855 1.047   1.634   2.189 2.422 6.049   5.512	0.649                 5.513	1.26 1.99 2.87   3.31 4.09 5.63   5.31	2.0 x105	100

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The HPLC method using soil-adsorption-reference data was applied for the determination of the adsorption coefficient (Koc) of Proketal.

The Koc and log Koc value of the test substance at neutral pH was:
Koc 2.0 x 10E5
log Koc 5.31
Area %: 100