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Environmental fate & pathways

Adsorption / desorption

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Administrative data

Endpoint:
adsorption / desorption: screening
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
10-Nov-1994 to 11-Jan-1995
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study OECD 106, GLP, Preliminary test.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1995
Report Date:
1995

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Principles of method if other than guideline:
PROTOCOL DEVIATIONS
1. The protocol states that sorption is investigated in three soils, and that desorption as well as adsorption is evaluated in the screening test For this
study, due to analytical difficulties resulting from the low solubility of the test substance, the screening test was not conducted.
As a result, only adsorption was evaluated, using a single soil.

2. The protocol states that the test concentrations, analytical standard CAS or Lot #, dosing solvent used CAS or Lot # and proposed expermiental
start, termination and draft report dates will be provided by amendment. An amendment was inadvertently not provided.
These deviations are not expected to alter the results of this study.
GLP compliance:
yes
Type of method:
batch equilibrium method
Media:
other: soil - biota

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Test temperature:
20 ± 2 °C

Batch equilibrium or other method

Details on matrix:
COLLECTION AND STORAGE
- Geographic location: soils were obtained from agricultural research sites or private gardens in Arkansas, Kansas and Washington (ultimately only
the Kansas soil (silty clay loam) was used
- Storage conditions: at room temperature in plastic bags prior to use

PROPERTIES
- Soil texture (Kansas silty clay loam)
- % sand: 11
- % silt: 58
- % clay: 31
- pH: 6.0
- Organic matter %: 3.0
- Organic carbon (%): 1.8 calculated from % organic matter using the formula: % organic carbon = % organic matter/1.7
- CEC (meq/100 g): 21.0
Details on test conditions:
Stock solutions were prepared in methanol to provide a concentration of 5.01 mg/mL.

Results and discussion

Adsorption coefficient
Type:
Koc
Value:
2 040 - 51 000

Results: Batch equilibrium or other method

Recovery of test material:
The recovered concentration of the prepared test solution was approximately 1.13 mg/L in the solution prepared at 2.0 mg/L in 0.01 M CaCl2.
The soil-less control concentration was 0.246 mg/L in extracted samples, indicating that some of the test substance adhered to the glass or to the
plastic caps.
Concentration of test substance at end of adsorption equilibration period:
In test systems containing soil, average aqueous concentrations were 0.0342, 0.0744, 0.118 and 0.0449 mg/L at solution:soil ratios of 5:1, 50:1,
100:1 and 200:1, respectively. Each value presented is the average of two measurements made from separate vessels, or from calculations thereof.

Any other information on results incl. tables

Aqueous lauryl methacrylate concentrations (mg/L) and calculated soil concentration and sorption coefficients from the preliminary test using Kansas silty clay loam.(a)

Test Solution                   Aqueous Phase After Equilibration

--------------------------------------------------------------------------------

Test       Percent              Soil conc.

Ratio   Vessels    Sorbed              Concentration    Kd        Koc

(mg/L)(b)   (%)                  (mg/kg)

--------------------------------------------------------------------------------

5:1    0.0342(c) 86.1                 1.06            36.0       2040

50:1    0.0744    69.8                 8.59            181       10200

100:1   0.118    52.1                  12.8            221       12500

200:1   0.0449   81.8                  40.2            899       51000

--------------------------------------------------------------------------------

(a) Test solution prepared at 2.00 mg/L had a measured concentration (average of 2 analyses) of 1.13 mg/L. Soil-less controls agitated in glass test vessels overnight had a measured aqueous concentration of 0.2462 mg/L. Soil-less control concentrations are used in calculation of percent sorbed, concentration in soil and Kd.

(b) Each value presented is the average of two measurements made from separate vessels, or from calculations thereof.

(c) For this ratio, the aqueous concentration in one replicate was below the established detection limit of 0.0262 mg/L; however, a peak was observed, and the concentration was calculated from the peak area in order to calculate an average

For Lauryl methacrylate, measured Koc values ranged from 2040 to 51000 and averaged 18900 +/- 21800 were determined in silty clay loam 

using solution:soil ratios ranging from 5:1 to 200:1. These values suggests that 

Lauryl methacrylate would be relatively "immobile".

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Lauryl methacrylate demonstrated high but variable sorption in this test. Koc, values at all solution:soil ratios were > 1000 which, in spite of the
variability, indicate a tendency of the material to sorb strongly to solids. This tendency indicates that the material may be expected to be
immobilized in soil when introduced into the environment. Desorption concentrations were not determined in this test.
Executive summary:

The sorption properties of lauryl methacrylate were determined in accordance with OECD Guideline 106 (1981). Preliminary testing was performed in duplicate with Kansas silty clay loam using 0.01 M CaCl2, and solution:soil ratios ranging from 5:l to 200:l. The initial solution concentration of 5 mg/L proved to be in excess of water solubility for lauryl methacrylate: measurement of test substance concentration in prepared solutions by HPLC-UV typically resulted in values around 1 mg/L. Following 16 hours of equilibration, the majority of the test substance had sorbed to the glass test vessels and/or Teflon-lined caps. Of the amount not sorbed to glass, 52.1 to 86.1% had sorbed to the soil at the varying solution:soil ratios, with no apparent relationship between sorption rate and soil mass. Koc-, values ranging from 2040 at a 5:1 solution:soil ratio to 51000 at a 200:l solution:soil ratio were calculated. Neither desorption from the silty clay loam nor sorption to other soil types was evaluated, due to the low solubility of the test substance and highly variable analytical results. Based on the estimates obtained, lauryl methacrylate is highly sorbed and may be expected to be immobilized in soil when introduced into the environment.

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