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Environmental fate & pathways

Adsorption / desorption

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Administrative data

Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
25 May 2000 to 30 May 2000
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study is performed according to OECD test guidance 121. However, the test substance was analyzed using a mobile phase that obscured a portion of the chromatogram. It is not established that the detection method is appropriate for the test substance. Further, it is not established that the reference substances provide an appropriate prediction of the sorptive behavior of the test substance.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report date:
2000

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
Principles of method if other than guideline:
Study predates adoption of the guideline and was based on a draft version of the guideline. The study as performed conforms to the guidance as adopted
GLP compliance:
yes
Type of method:
HPLC estimation method

Test material

Constituent 1
Chemical structure
Reference substance name:
-
EC Number:
435-790-1
EC Name:
-
Cas Number:
297730-93-9
Molecular formula:
C9H5F15O
IUPAC Name:
3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-(trifluoromethyl)hexane
Details on test material:
- Name of test material (as cited in study report): T-7145
- Physical state: Clear colourless liquid
- Analytical purity: Not reported, expected to be >99.5%
- Stability under test conditions: Stable
- Storage condition of test material: At room temperature in the dark
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
PHYSICO-CHEMICAL PROPERTIES
- Dissociation constant: No ionizable groups
- pKa: No ionizable groups
- Base or acid catalysis of test material: Stable under storage
- Stability of test material at room temperature: Stable

Study design

Test temperature:
35 °C

HPLC method

Details on study design: HPLC method:
EQUIPMENT
- Apparatus: Not reported
- Type: Hypersil BDS-CN; 150x4.6 (I.D.) mm; dp=5 um (AIItech, Deerfield, USA)
- Type, material and dimension of analytical (guard) column: None reported
- Detection system: Refractive index detection
MOBILE PHASES
- Type: isocratic, 55/45 (v/v) methanol/Milli-Q water
- Experiments with additives carried out on separate columns: No additives
- pH: unbuffered
- Solutes for dissolving test and reference substances: Test substance was dissolved in acetonitrile and diluted in acetonitrile for injection. Reference substances were dissolved in methanol to make stock solutions and diluted 20/80 (v/v) in mobile phase for injection.
DETERMINATION OF DEAD TIME
- Method: by use of formamide (inert substance which is not retained by the column) in 20/80 (v/v) methanol/mobile phase
REFERENCE SUBSTANCES
- Identity:
Phenol
N,N-dimethylbenzamide
Methylbenzoate
3,5-Dinitrobenzamide
Naphthalene
Mercaptodimethur
Fenthion
2,4-DDT
DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 10 microliters of a 618 mg/L solution
- Quantity of reference substances: 10 microliters of solution containing 140 mg/L to 530 mg/L
- Intervals of calibration: Not reported.
REPETITIONS
- Number of determinations: duplicate injections of test substance, four injections of reference substances and formamide
EVALUATION
- Calculation of capacity factors k':
k' = (tr - to)/to.
tr, retention time of test or reference substance.
to, retention time of formamide.
- Calculation of retention times: Not reported.
- Determination of the log Koc value: linear regression of log k' v. log Koc for reference substances.

Results and discussion

Adsorption coefficientopen allclose all
Type:
Koc
Value:
75 800
Type:
log Koc
Value:
4.88

Results: HPLC method

Details on results (HPLC method):
- Retention times of reference substances used for calibration: See Table 1
- Details of fitted regression line (log k' vs. log Koc): Iogk' = 0.285 * IogKoc - 1.455 (r=0.947, n=8)
- Graph of regression line attached: Prepared for this robust study summary, see Figure 1
- Average retention data for test substance: tr = 3.751 min
- Average retention data for unretarded component (formamide): to = 2.015 min

Any other information on results incl. tables

Table 1, Results of the HPLC method

Table 1, Results of the HPLC method
Substance tr k' Iog k' Iog Koc Koc
Reference substance          
Phenol 2.157 0.070 -1.152 1.32
N,N-dimethylbenzamide 2.187 0.085 -1.069 1.52
Methylbenzoate 2.313 0.148 -0.830 1.80
3,5-Dinitrobenzamide 2.224 0.103 -0.985 2.31
Naphthalene 2.593 0.287 -0.542 2.75
Mercaptodimethur 2.487 0.234 -0.631 3.10
Fenthion 3.018 0.498 -0.303 3.30
2,4-DDT 4.367 1.167 0.0671 5.63
Test substance          
major component 3.751 0.862 -0.0647 4.881 7.58E+04
1, Interpolated from the regression line: Iogk' = 0.285*IogKoc- 1.455 (r = 0.947)

Figure 1, Regression of log - capacity factor (k') v. log - Adsorption coefficient (Koc)

--> SEE ATTACHMENT 1 - in section attached background material

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
At 35°C, the adsorption coefficient Koc of CAS# 297730-93-9 on soil and sewage sludge is 7.58E+04 (Iog Koc = 4.88)
Executive summary:

The adsorption coefficient of CAS# 297730-93-9 on soil and sewage sludge (Koc) was studied by HPLC.  CAS# 297730-93-9 was dissolved in acetonitrile. Eight reference substances with retention times bracketing that of the test substance were dissolved in 20/80 methanol/mobile phase and used to create a standard curve.  HPLC conditions were: 10 microliter injection volume, 55/45 methanol/Milli-Q water mobile phase, 1 mL/minute flow rate, in a 35°C temperature controlled environment.  The column was a Hypersil BDS-CN; 150x4.6 (I.D.) mm; dp=5 um with no guard column. Formamide was used to establish the retention time of unretarded substances (to). Reference substances were injected four times to determine their retention times (tr), while CAS# 297730-93-9 was injected in duplicate. The regression curve of log-capacity factor (log k') v. log Koc for references substances was Iog k' = 0.285 * Iog Koc - 1.455 (r = 0.947), where k' = (tr-to)/to. At 35°C, the Koc of CAS# 297730-93-9 on soil and sewage sludge is 7.58E+04.

 

This study is classified as acceptable and satisfies the guideline requirements for test method OECD121, Estimation of the adsorption coefficient (Koc ) on soil and on sewage sludge using high performance liquid chromatography (HPLC).