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Type of information:
experimental study
Adequacy of study:
key study
Study period:
07 Sept. 2010-15 Nov. 2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No information available on substrate

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report date:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
equivalent or similar to guideline
Guideline:
other: Soil samples prepared equivalent to OECD315 (Bioaccumulation in sediment-dwelling benthic oligochaetes).
Deviations:
not applicable
Qualifier:
equivalent or similar to guideline
Guideline:
other: Soil suspensions analysis equivalent to USEPA method 8260 (Measurement of purgeable organic compounds in water by capillary column GC/MS.
Deviations:
not applicable
Principles of method if other than guideline:
Water suspensions of spiked soils were analyzed by purge-and-trap GC/MS to assess whether CAS# 297730-93-9 concentrations could be stably maintained in an aqueous system.
GLP compliance:
no
Type of study:
volatility
Media:
other: water - sediment - air

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): HFE 7500
- Substance type: Pure active substance
- Analytical purity: 99.7%
- Stability under test conditions: Stable
- Storage condition of test material: Room temperature

Results and discussion

Any other information on results incl. tables

Test 1a) No standard curve was run, but duplicate 50 ng/mL standards agreed within ca. 2%. Average recovery from the sand spike triplicate was 50.1% (relative standard deviation [RSD], 12%).

Test 1b) The standard curve ranged from 1.0 ng/mL to 20.0 ng/ml in reagent water. Limit of quantitation is defined based on the lowest standard concentration, and for this this curve is equivalent to 10 % recovery of CAS# 297730-93-9 from the suspension. Average recovery from the sand:soil mixtures was 20.1% (RSD, 3.0%). Detailed results are given in Table 1. It is apparent that recovery from the soil:sand mixture is considerably less than from pure sand. Two additional samples were analyzed after overnight storage. The sample which was left capped until analysis had a recovery of 22.7%, demonstrating that the analyte was stable in the mixture when in a closed system. The sample which was uncapped had 5.8% recovery.

Table 1, Individual recoveries for CAS# 297730-93-9 spiked to soil:sand mixtures at 10 ng/g

Matrix/Replicate

Measured concentration (ng/g)

Percent recovery

Spike 1

2.05

20.5

Spike 2

1.94

19.4

Spike 3

2.03

20.3

Spike 4

2.08

20.8

Spike 5

1.99

19.9

Spike 6

1.95

19.5

Spike 7

1.96

19.6

Spike 8

1.93

19.3

Spike 9

2.02

20.2

Spike 10

2.01

20.1

Spike 11

2.11

21.1

Spike 12

2.08

20.8

Average recovery

20.1

% RSD, recovery

 

3.0

Test 2a) Limit of quantification was 10% recovery based on standard curve. Detailed results are given in Table 2. Loss of analyte from the triplicate stored capped 2 h was little different than the triplicate analyzed immediately. 2-Hour loss of analyte was greatest from the triplicate which was allowed to stand open after addition of water.

Table 2, Recovery of CAS# 297730-93-9 from spiked soil:sand and soil:sand:water mixtures

Test condition

Soil mixture capped between aliquot and water addition?

Soil:water mixture capped after water addition?

Average recovery for replicate

Replicate i)

yes, samples analyzed immediately

yes

18.8%

Replicate ii)

yes, water added immediately

no, samples held 2 hours after water addition

<10 % (LOQ)

Replicate iii)

yes, samples held 2 hours prior to water addition

yes

17.8%

Replicate iv)

no, samples held 2 hours prior to water addition

yes

11.4%

Test 2b) Recovery of CAS# 297330-93-9 from artificial sediment (soil:sand:5 mL water) in continuously-capped vials (Vials 1A-3A, see Table 3) was 20.2% - 23.0% at up to 12 hours standing before analysis, demonstrating that loss of analyte was avoided when vials were tightly capped. Analytical results for uncapped samples were mostly below limit of quantitation, so results are based on SIM area counts. Details are provided in Table 3. Dissipation evidently follows 2nd-order kinetics based on linearity of the characteristic plot in Figure 1. Half-lives based on 2nd-order kinetics depend on initial concentration as t½ = 1/k[A0], and therefore cannot be generalized. A rough estimate of half-life for CAS# 297730-93-9 based on the 1st –order approximation in Figure 2 is 13.7 ± 64.8 min.

Table 3, Kinetic results for CAS# 297730-93-9 in vials open to air

Sample

Volatilization time (min)

Sample weight (g)

Area count

Percent recovery

Raw

Weight normalized

Vial 1A

none

5.215

11400

10930

108

Vial 13

10

5.214

1361

1305

12.9a

Vial 1

20

5.162

1745

1690

16.7

Vial 2

20

5.170

693

670

6.6

Vial 3

30

5.238

448

428

4.2

Vial 4

45

5.333

312

293

2.9

Vial 5

45

5.381

316

294

2.9

Vial 2A

none

5.411

10910

10081

99.9

Vial 6

60

5.407

239

221

2.2

Vial 7

75

5.211

226

217

2.1

Vial 8

75

5.323

194

182

1.8

Vial 9

90

5.125

failed

failed

failed

Vial 10

105

5.130

136

133

1.3

Vial 11

120

5.021

138

137

1.4

Vial 12

0

5.243

6930

7267

68.6b

Vial 3A

none

5.075

9414

9275

91.9

a, final aliquot withdrawn from spiked soil:sand mixture.  Volatilization losses of up to 35% may have occurred during sample aliquotting.

b, Penultimate aliquot withdrawn from spiked soil:sand mixture, used to assess volatilization losses during aliquotting.

Figure 1, see attachment 1

Figure 2, see attachment 2

Test 2c) Samples which had been previously analyzed under Test 1b were retained 13 days and subjected to an additional purge & trap analysis with no additional spiking. Comparative results are provided in Table 4. As amount of analyte recovered is approximately the same at both times, it is evident that the analyte redistributes to an extractable form.

Table 4, Comparative results for spike samples (see Table 1) reanalyzed after 13 days

Sample

Day 1 results

Day 13 results

Measured concentration (ng/g)

% recovery

Measured concentration (ng/g)

% recovery

Spike 1

2.05

20.5

2.20

22.0

Spike 2

1.94

19.4

2.13

21.3

Test 3) Sample substrates (10 mL water plus 0 g to 5.0 g soil mixture) were equilibrated 4 days with 3386 ng CAS# 297730-93-9 vapor injected to the sample vial headspace. Vials were allowed to settle, and a sample of the aqueous supernatant only was withdrawn and subjected to purge & trap analysis. CAS# 297730-93-9 levels were below quantification limits in all cases. However, neither the vial headspace nor the suspended material was analyzed.

In addition, soil mixtures which had been exposed to CAS# 297730-93-9 vapor without additional water were analyzed. Results (Table 5) were in excess of the quantification limit. A rough estimate of mass per gram of soil indicates that adsorption is impacted by amount of soil present.

Table 5, Concentration of CAS# 297730-93-9 sorbed to 90% soil:10% sand mixture from the gas phase

Mass of mixture

Headspace purge

Concentration (ng/mL water phase)a

Total amount recovered (ng)b

Percent recoveryc

Concentration on soil (ng/g)

0.5 gram

N2 stream

393

1965

58%

3930

0.5 gram

15 seconds passive air contact

356

1780

53%

3560

5.0 gram

N2 stream

165

825

24%

165

5.0 gram

15 seconds passive air contact

193

965

28%

193

a, based on 5 mL reagent water added for purge & trap analysis

b, based on concentration and 5 mL total volume analyzed

c, Percent recovery = 100% * amount recovered / 3386 ng spike

Taken together, these results suggest that CAS# 297730-93-9 concentrations can only be stably maintained in tightly closed systems. CAS# 297730-93-9 in a sealed vessel was able distribute from the gas phase to the moist soil, however in an open container the tendency is to volatilize from the moist soil to the gas phase. Similarly, CAS# 297730-93-9 volatilizes quickly from the soil-water suspension used to represent sediments.

Applicant's summary and conclusion

Conclusions:
CAS# 297730-93-9 cannot be stably maintained in open test systems.
Executive summary:

Volatilization of CAS# 297730-93-9 from a soil:sand and soil:sand:water mixtures used to represent aquatic sediment was examined to address the feasibility of testing of bioconcentration in Oligochaete worms under OECD315. CAS# 297730-93-9 could be maintained in tightly capped vials, but in open systems analyte was lost in a fashion that appears to depend on water tension. CAS# 297730-93-9 volatilized from uncapped artificial sediment with a half-life of 13.7 ± 64.8 minutes. The substance was lost more slowly from uncapped moist soil. CAS# 297730-93-9 injected to the gas phase above artificial sediment could not be detected in the water phase (solids not tested). The substance partitioned to moist soils when injected to the gas phase in a sealed container, however in open containers the flux was out of the soil. Based on these results, CAS# 297730-93-9 cannot be stably maintained in open test systems.

The test was conducted using materials equivalent to those described in OECD TG315 and TG207. Analysis was by purge & trap GC/MS according to USEPA method 8260. The soil analysis is out of date and for a different lot of the soil. The headspace was not analyzed, nor were water and solid phases analyzed separately. No mass balance is therefore possible. This study is classified as reliable with restrictions.