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Administrative data

Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
October 24, 2002 till October 25, 2002
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study according to OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC)) under GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report date:
2009

Materials and methods

Test guideline
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 (incl. QA statement)
Type of method:
HPLC estimation method
Media:
soil

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Identity: ZP-TIX 1014
Batch: NW-01-028
Purity > 99%,
Appearance: Solid
Expiration date: 30.12.2001
Storage: At room temperature at about 20°C

The test item consists of three components, which appears as three peaks in the HPLC-chromatogramm
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
PHYSICO-CHEMICAL PROPERTIES
- Water solubility < 0.9 mg/L using the column elution method
- No test item was detectable in the n-octanol samples measured by HPLC
Radiolabelling:
no

Study design

HPLC method

Details on study design: HPLC method:
Principle:
For the estimation of the adsorption coefficient, the HPLC-method was used. Therefore, an analytical column packed with a commercially available, cyanopropyl solid phase containing lipophilic and polar moleties was used. A moderately polar stationary phase based on a silica matrix was used.
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 the 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 adsorption coefficient on organic matter to be established.

Definitions:
Kd: Distribution coefficient defined as the ratio of equillbrium concentrations Ce of a dissolved substance in a two-phase system consisting of a solid (soil or sewage sludge) and an aqueous phase; it is a dimensionless value varying with solid properties.

Kd=(Csoil/sludge) / (Cwater)

C = Concentration of the test item at equillbrium (µg/g)

Koc: Distribution coefficient (Kd) normalised to the organic carbon content (OC) of a solid; particularly for non-ionised chemicals, it is an approximate indicator for the strength of adsorption between a substance and the solid and allows comparisons to be made between different chemicals.

Koc=Kd/oc

The adsorption coefficient (Koc) is deduced from the capacity factor (k') using a calibration plot of log k' versus log Koc of the selected reference items.

k'= (tR-tO)/tO

k' = HPLC retention time of test or reference items (min.)
tR = HPLC dead time (min.)
(measurement of the retention time of sodium nitrate)

The adsorption coefficient (Koc) of the test item will be interpolated from the calibration curve which will be established by correlation of the log Koc values of various reference items with their log k' values.

Test System:
This method utilises a high performance liquid chromatograph with UV-VIS detector,
reversed phase column and an aqueous mobile phase. Details are given below.

Performance of the Test:
Test Item Solution:
ZP-TIX 1014 (22 mg) was dissolved in THF (10 mL) to prepare a stock solution of 2200 µg/mL. The stock solution (1000 µL) was diluted with THF to 10 mL to obtain a standard solution of 220 µg/ml. The pH value of the test item solution was determined to be 6.1. The test item solution was injected three times.

Reference Solutions:
The reference items were chosen from the list given in the OECD Guidellne No. 121.
Stock solutions of the reference Items In acetonitrile were prepared as described:
10 mg of the reference item phenol were dissolved in 10 mL acetonitrile. 24 mg of the reference items isoproturon and linuron and 25 mg of the reference Items 2,4-DDT, pyrazophos and diclofop-methyl were each dissolved in 25 mL acetonitrile.
A combined reference solution was prepared by transferring 145 µL of the phenol stock solution, 150 µL of the isoproturon stock solution, 75 µL of the linuren stock solution, 180 µL of the diclofop-methyl stock solution, 1250 µL of the pyrazophos stock solution and 335 µL of the DDT stock solution into one volumetrie flask and diluting to a volume of 10 mL with a solvent mixture of acetonitrile and water (55:45; vIv). This reference solution was injected six times.
Sodium nitrate (25.5 mg) was diluted to 100 mL with acetonitrile to obtain a stock solution. The stock solution (100 J.l1) was diluted to 1 mL with a solvent mixture of acetonitrile and water (55:45; v/v). This sodium nitrate solution was injected two times for the determination of the dead time of the HPLC system.

HPLC-Conditions:
The firsts test to determine the adsorption coefficient (Koc) of ZP- TIX 1014 were performed with methanol as organic solvent. The solvent mixture of methanol and water was not sufficient to elute the test item from the column. Referring to this, acetonitrile was used as organic solvent.

Apparatus: Varian Autosampier 9095 Varian Pump ProStar 230 Varian Detector 9050
Jones column oven 7990
Column: LiChrospher 100 CN, Part. Size 5 µm, 250 mm . 4 mm
Mobile Phase: Water (MiIIi-Q) / Acetonitrile (45:55; v/v); pH 7.0
Detection: 220 nm for the test item solution
210 nm for the reference items and for sodium nitrate
Temperature: 25°C
Injection Volume: 10 µL
Flow: 1.0 mL/min

Results and discussion

Adsorption coefficientopen allclose all
Type:
Koc
Value:
> 583 737 - < 13 753 387
Type:
log Koc
Value:
> 5.8 - < 7.1

Results: HPLC method

Details on results (HPLC method):
In conclusion tho log of the adsorption coefficient ( log Koc) of ZP-TIX 1014) was estimated to be
log Koc = 5.8 (Koc = 583737) first test item peak
log Koc = 6.4 (Koc = 2717413) second test item peak
log Koc = 7.1(Koc = 13583387) third test item peak

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The test item ZP-TIX 1014 was found to have a adsorption coefficient (Log Koc) between 5.8 and 7.1.

log Koc = 5.8 which is equal to Koc value of 583737 (first test item peak)
log Koc = 6.4 which is equal to Koc value of 2717413 (second test item peak)
log Koc = 7.1 which is equal to Koc value of 13583387 (third test item peak)

These values indicate that ZP-TIX 1014 is immobile and remains preferably in soil.
Executive summary:
The determination of the adsorption coefficient (Koc) of ZP-TIX 1014 according to the OECD Guideline for the Testing of Chemicals, No. 121, Estimation of the Adsorption Coefficient (Koc) on Soil and Sewage Sludge using High Performance Liquid Chromatography (HPLC), January, 2001 and the EC Directive 2001/59, C.19.

 

The test item solution was injected three times and the combined reference solution was injected six times.

 

The test item consists of three components, which appear as three peaks in the HPLC¬chromatogram. The calculation was performed for each component of ZP-TIX 1014.

 

The retention time of each test item component was larger than the largest retention time of the reference item 2.4-DDT. Therefore, the log Kocwas extrapolated from the regression curve (log k' vs. log Koc) and was found to be 5.8 (first test item peak), 6.4 (second test item peak) and 7.1 (third test item peak). In the present study the reference items covered the range of log Koc= 1.32 to log Koc= 5.63.

 

The chromatography of the test item resulted in three main peaks with well-defined and reproducible retention times. The HPLC method was therefore considered to be suitable for the purpose of the study. Based on the chromatographic data, ZP-TIX 1014 was considered to be stable during the test procedure.

 

In conclusion, the log of the adsorption coefficient (Koc) of ZP-TIX 1014 was estimated to be

log Koc= 5.8 which is equal to Koc value of 583737 (first test item peak)

log Koc= 6.4 which is equal to Koc value of 2717413 (second test item peak)

log Koc= 7.1 which is equal to Koc value of 13583387 (third test item peak)

using the HPLC method. These values indicate that ZP-TIX 1014 is immobile and remains preferably in soil.

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