Carbamic acid, N-[(1R)-2-hydroxy-1-phenylethyl]-, 1,1-dimethylethyl ester

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 04 2016 to Dec 06 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EU Method C.18 (Adsorption / Desorption Using a Batch Equilibrium Method)

Version / remarks:

EC Directive 2001/59, C.18 Adsorption/desorption using a batch equilibrium method. 0. J. L225, 2001.

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)

Version / remarks:

Guideline for the testing of chemicals 106. Adsorption - Desorption Using a Batch
Equilibrium Method. Paris: OECD, 2000.

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: GB/T 21851

Version / remarks:

GB/T 21851-2008, Chemicals-Adsorption-desorption using a batch equilibrium method [SJ.Beijing: SAC, 2008.

Deviations:

no

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: 2013:47-81

Version / remarks:

Chemical Registration Center of MEP. The Guidelines for the Testing of Chemicals, PhysicChemical Properties and Physical Hazards [M]. 2nd edition. Beijing: China Environment Press. 2013:47-81.

Deviations:

no

Test guideline 5

Qualifier:

according to guideline

Guideline:

other: HJ/T 153-2004

Version / remarks:

HJ/T 153-2004, The guidelines for the testing of chemicals [SJ. Beijing: SEPA, 2004.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

batch equilibrium method

Media:

soil

Test material

Test material information

Constituent 1

Reference substance name:

Carbamic acid, N-[(1R)-2-hydroxy-1-phenylethyl]-, 1,1-dimethylethyl ester

EC Number:

600-273-1

Cas Number:

102089-74-7

Molecular formula:

C13H19NO3

IUPAC Name:

Carbamic acid, N-[(1R)-2-hydroxy-1-phenylethyl]-, 1,1-dimethylethyl ester

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

Purity. 99.99%

Radiolabelling:

not specified

Study design

Test temperature:

The soils were air-dried at ambient temperature (20°C ~ 25°C)

Batch equilibrium or other method

Analytical monitoring:

not specified

Details on sampling:

4.2 Preparation of the Standard Stock Solution
The standard stock solution I of the test substance (10011 mg/L) was prepared by dissolving 1.0011 g test substance into 100 mL acetonitrile.

4.3 Test 1 - Preliminary Study
(1) Selection of optimal soil/solution ratios
Two soil types (A, B) were selected.
Three soil/solution ratios described as follows for A, B soil was adopted:
- 50 g soil and 50 mL aqueous solution (0.01 mol/L CaCh solution) of the test substance (ratio
1/1);
- 10 g soil and 50 mL aqueous solution (0.01 mol/L CaCh solution) of the test substance (ratio
1/5);
- 2 g soil and 50 mL aqueous solution (0.01 mol/L CaCh solution) of the test substance (ratio
1/25).
One control sample with only the test substance in 0.01 mol/L CaCh solution (no soil) was subjected to precisely the same steps as the test systems, in order to check the stahility of the test substa.r1c~ in CaCb solution and its possible adsorption on the surfaces of the test vessels.
A blank run per soil with the same amount of soil and total volume of l 00 mL 0.01 mol/L CaCh solutions (without test substance) were subjected to the same test procedure. This serves as abackground control during the analysis to detect interfering compounds or contaminated soils.
All the experiments, including controls and blanks, were performed in duplicate.
The air-dried soil samples were equilibrated by shaking with a minimum volume of 49.75 mL of 0.01 mol/L CaCb overnight (12 h) before the day of the experiment, respectively. Afterwards, 0.250 mL of the stock solution (10011 mg/L) of the test substance was added to prepare the test solution of 50.0 mg/L, respectively.
In the preliminary study, samples were collected sequentially over a 48 h period of mixing (in the test at 2h, 4h, 6h, 1 Oh, 24h and 48 h). After centrifugation and separation, the water phase and soil phase of the first tube was measured after 2 h, that of the second tube after 4 h, that of the third after 6 h, etc.

(2) Determination of adsorption equilibration time and of the amount of test substance adsorbed at equilibrium
As already mentioned above, plots of Aii or C :~s versus time permit estimation of the achievement of the adsorption equilibrium and the amount of test substance adsorbed at equilibrium. Equilibration time was the time the system needs to reach a plateau.

(3) Adsorption on the surface of the test vessel and stability of the test substance
Some information on the adsorption of the test substance on the surface of test vessels, as well as its stability, could be derived by analyzing the control samples.

Matrix properties

Matrix properties 1

Matrix no.:

#1

Matrix type:

other: Jilin (black soil)

% Org. carbon:

6.54

pH:

7.28

CEC:

28.87 other: cmol/kg

Matrix properties 2

Matrix no.:

#2

Matrix type:

other: Jiangxi (red soil)

% Org. carbon:

1.36

pH:

4.6

CEC:

11.53 other: cmol/kg

Matrix properties 3

Matrix no.:

#3

Matrix type:

other: Jiangsu (paddy soil),

% Org. carbon:

5.36

pH:

6.81

CEC:

22.9 other: cmol/kg

Matrix properties 4

Matrix no.:

#4

Matrix type:

other: Shandong (yellow soil)

% Org. carbon:

1.39

pH:

7.84

CEC:

7.08 other: cmol/kg

Matrix properties 5

Matrix no.:

#5

Matrix type:

other: Gansu (meadow soil)

% Org. carbon:

1.39

pH:

7.96

CEC:

22.13 other: cmol/kg

Details on matrix:

The soils were characterized by four parameters considered to be largely responsible for the adsorptive capacity: organic carbon, clay content, soil texture, and pH. The soils selected for this study is from Jilin (A black soil), Jiangxi (B red soil), Jiangsu (C paddy soil), Shandong (D yellow soil) and Gansu (E meadow soil) and the properties of soil which were determined by Institute of soil science, Chinese academy of sciences were shown in Table 1. The soil samples were transported using containers and under temperature conditions which guarantee that the initial soil properties were not significantly altered.
The soils were air-dried at ambient temperature (20°C ~ 25°C). The soils were sieved to a particle size 0.3 mm. The moisture content of each soil was determined on three aliquots with heating at 105°C until there is no significant change in weight. For all calculations the mass of soil refers to oven dry mass, i.e. the weight of soil corrected for moisture content.

Duration of adsorption equilibration

Duration of adsorption equilibration 1

Sample No.:

#1

Duration:

48 h

Initial conc. measured:

10 mg/kg soil d.w.

Duration of adsorption equilibration 2

Sample No.:

#2

Duration:

48 h

Initial conc. measured:

20 mg/kg soil d.w.

Duration of adsorption equilibration 3

Sample No.:

#3

Duration:

48 h

Initial conc. measured:

50 mg/kg soil d.w.

Duration of adsorption equilibration 4

Sample No.:

#4

Duration:

48 h

Initial conc. measured:

70 mg/kg soil d.w.

Duration of adsorption equilibration 5

Sample No.:

#5

Duration:

48 h

Initial conc. measured:

100 mg/kg soil d.w.

Duration of desorption equilibration

Duration of desorption equilibration 1

Sample no.:

#1

Conc. of adsorbed test mat.:

10 mg/kg soil d.w.

Duration of desorption equilibration 2

Sample no.:

#2

Conc. of adsorbed test mat.:

20 mg/kg soil d.w.

Duration of desorption equilibration 3

Sample no.:

#3

Conc. of adsorbed test mat.:

50 mg/kg soil d.w.

Duration of desorption equilibration 4

Sample no.:

#4

Conc. of adsorbed test mat.:

70 mg/kg soil d.w.

Duration of desorption equilibration 5

Sample no.:

#5

Conc. of adsorbed test mat.:

100 mg/kg soil d.w.

Computational methods:

5 Data Processing
5.1 Adsorption
( 1) Calculation of Ati
The adsorption Ati was defined as the percentage of substance adsorbed on the soil related to the quantity present at the beginning of the test, under the test conditions. If the test substance was stable and did not adsorb significantly to the container wall, Ati was calculated at each time point ti according to the equation:
Ati = msads(ti)*100 / mo
where:
Ati = adsorption percentage at the time point ti (% );
msads (ti)= mass of test substance adsorbed on the soil at the time ti (μg);
mo= mass of test substance in the test tube, at the beginning of the test (μg).
The terms of this equation could be calculated as follows:
mo= C0 * Vo (μg)
msads (ti) = m0 -Cadsaq(ti) * V0 (μg)
Where:
Co= initial mass concentration of the test solution in contact with the soil (μg cm-3);
Cadsaq(ti)= mass concentration of the substance in the aqueous phase at the time ti that the analysis is performed (μg cm-3); this concentration is analytically determined taking into account the values given by the blanks.
Vo = initial volume of the test solution in contact with the soil ( cm3).
The values of the adsorption percentage Ati orc:~s(tJ are plotted versus time and the time after which the sorption equilibrium attained was determined.

(2) Calculation of Distribution Coefficient Kct
The distribution coefficient Kct was the ratio between the content of the substance in the soil phase and the mass concentration of he substance in the aqueous solution, under the test conditions, when adsorption equilibrium was reached.
K = Cadsaq(eq) = msads(eq) .~ (cm3 -1)
d caadq s( eq ) maaqd s( eq ) msoil g
where:
c:ds ( eq) =content of the substance adsorbed on the soil at adsorption equilibrium (μg g-1
);
c:~s ( eq) = mass concentration of the substance in the aqueous phase at adsorption equilibrium
(μg cm-3
); this concentration is analytically determined taking into account the values given by
the blanks.
m:ds ( eq) = mass of the test substance adsorbed on the soil at adsorption equilibrium (μg);
m:~s ( eq) = mass of the test substance in the solution at adsorption equilibrium (μg);
msoil =quantity of the soil phase, expressed in dry mass of soil (g);
V0 =initial volume of the aqueous phase iri contact with the soil (cm3
).
The relation between Aeq and Kct is given by:
Kd = Aeq .~ (cm3g-1)
100-A.q m,0il
wht:rn: Aeq =percentage of adsorption at adsorption equilibrium,%.

(3) Calculation of organic carbon normalized adsorption coefficient Koc
The organic carbon normalized adsorption coefficient Koc relates the distribution coefficient Kct to
the content of organic carbon of the suil samplt:.
100 3 -1 K 0c =Kd ·~·-(cm g )
%oc
where: %oc =percentage of organic carbon in the soil sample (g i 1
).

5.2 Adsorption Isotherms .
The Freundlich 11rlsorption isotherms equation re.lated the amount of the test substance adsorbed
to the concentration of the test substance in solution at equilibrium.
The data were treated as under "Adsorption" and, for each test tube, the content of the test
substance adsorbed on the soil after the adsorption test ( c:ds ( eq) ), elsewhere denoted as x/m)
was calculated. It was assumed that equilibrium had been attained and that c:ds ( eq) represented
the equilibrium value:
ads( ) [C c•ds(e )] V
C
ads( ) m, eq 0 - aq q . 0 ( -1)
s eq = = μgg
msoil msoil
The Freundlich adsorption equation was shown as followed:
c:ds ( eq) = K~ds . c::s ( eq)11n (μg g-1)
or in the linear form:
where:
K~ds = Freudlich adsorption coefficient; its dimension was cm3 i 1 only if 1/n = 1; in all other
cases, t h e s l ope 1/ n was m· tro d uce d m· t h e d1' mens1· 0n o f KaFd s ( μg 1-1/n ( cm3 )1/n g -1) ;
n =regression constant; 1/n generally ranges between 0.7 - 1.0, indicating that sorption data was
frequently slightly nonlinear.
The equations above were plotted and the values of K~ds and l/n were calculated by regression
analysis using the second equation. The correlation coefficient r2 of the log equation was also
calculated.

5.3 Desorption
( 1) Calculation of Di;
The desorption is defmed as the percentage of the test substance which is desorbed, related to the
quantity of substance previously adsorbed, under the test conditions:
m des (t . ) · 100
__aq -"--...,....--1 __ (%)
m fds (eq )
where:
Dti = desorption percentage at a timtl point L (% );
m~~· (t;) =mass of the test substance desorbed from soil at a time point ti, (μg);
m:ds ( eq) = mass of the test substance adsorbed on soil at adsorption equilibrium (μg).
At a time point t;, the mass of the test substance is measured in the aqueous phase taken from the
tube i (Vr;), and the mass desorbed is calculated according to the equation:
des{,) des{, )(Vol maq A \f; = m,,, \f; I - maq
v,.
At desorption equilibrium ti= teq and therefore m~:· (ti)= m~:· ( eq)
m:s (ti) = mass of the test substance analytically measured at a time ti in a solution volume Vr
which is taken for the analysis (μg);
111,~1 =mass or I.he l.esl. suhsl.arn:e Jen. over from I.he adsorpl.ion equilihriurn due l.o im:mnplel.e
volume replacement (μg);
v; = volume of the solution taken from the tube(i) for the measurement of the test substance, in
desorption kinetics experiment ( cm3
).
m:" = m:~' (eq )[Vo :
0
VR J
m::s =mass of the test substance in the solution at adsorption equilibrium (μg);
VR = volume of the supernatant removed from the tube after the attainment of adsorption
equilibrium and replaced by the same volume of a 0.01 mol/L CaC12 solution (cm3
);
The values of the desorption D1; (according to the needs of the study) are plotted versus time and
the time after which the desorption equilibrium is attained is determined.

(2) Calculation of distribution coefficient Kdes
The apparent desorption coefficient (Kdes) is, under the test conditions, the ratio between the
content of the substance remaining in the soil phase and the mass concentration of the desorbed
substance in the aqueous solution, when desorption equilibrium is reached:
m~ds (eq)- mg&s (eq) VT
Kdes = x--
mg&s (eq) msoil
where:
Kdes =desorption coefficient (cm3g-1
);
m~~8 (eq) =total mass of the test substance desorbed from soil at desorption equilibrium (~tg);
VT= total volume of the aqueous phase in contact with the soil during the desorption kinetics test
(cm3).

5.4 Desorption isotherms
The Freundlich desorption isotherms equation relates the content of the test substance remaining
adsorbed on the soil to the concentration of the test substance in solution at desorption
equilibrium.
For each test tube, the content of the substance remaining adsorbed on the soil at desorption
equilibrium is calculated as follows:
m ads (eq) _ m des (eq)
C sd es (eq) = __s __m _s_o_ial_q, __ _ ( μg g - 1 )
where:
c~es ( eq) = content of the test substance remaining adsorbed on the soil at desorption equilibrium
(μg ti);
m::s ( eq) = mass of the substance in the solution at adsorption equilibrium (μg);
The Freundlich desorption equation is shown as follow:
or in the linear form:
where:
K~es =Freundlich desorption coefficient;
n = regression constant;
c~:s ( eq) = mass concentration of the substance in the aqueous phase at desorption equilibrium
(μg cm-3
).
The equations above can be plotted and the value of K~es and l/n are calculated by regression
analysis using the equation.

5.5 Mass balance
The mass balance (MB) is defined as the percentage of substance which can be analytically
recovered after an adsorption test versus the nominal amount of substance at the beginning of the
test. The mass balance for the adsorption is calculated as follows:
( ads( ) )lOO MB= Vrec·Caq eq +me (%)
Vo·Co
Where:
MB = mass balance (% );
me= total mass of test substance extracted from the soil and walls of the test vessel in two steps
(μg);
Co= initial mass concentration of the test solution in contact with the soil (μg cm-3
);
Yrec =volume of the supernatant recovered after the adsorption equilibrium (cm3
).

Results and discussion

Adsorption coefficient

Adsorption coefficient 1

Sample No.:

#1

Type:

Kd

Value:

0.53 other: Cm3g-1

pH:

839

Temp.:

20 °C

% Org. carbon:

6.54

Adsorption coefficient 2

Sample No.:

#2

Type:

Kd

Value:

0.088 other: Cm3g-1

pH:

4.6

Temp.:

20 °C

% Org. carbon:

1.36

Adsorption coefficient 3

Sample No.:

#3

Type:

Kd

Value:

1.68 other: Cm3g-1

pH:

6.81

Temp.:

20 °C

% Org. carbon:

5.36

Adsorption coefficient 4

Sample No.:

#4

Type:

Kd

Value:

0.16 other: Cm3g-1

pH:

7.84

Temp.:

20 °C

% Org. carbon:

1.39

Adsorption coefficient 5

Sample No.:

#5

Type:

Kd

Value:

5.33 other: Cm3g-1

pH:

7.96

Temp.:

20 °C

% Org. carbon:

7.96

Adsorption coefficient 6

Sample No.:

#1

Type:

Koc

Value:

8.12 other: Cm3g-1

Adsorption coefficient 7

Sample No.:

#2

Type:

Koc

Value:

6.47 other: Cm3g-1

Adsorption coefficient 8

Sample No.:

#3

Type:

Koc

Value:

31.3 other: Cm3g-1

Adsorption coefficient 9

Sample No.:

#4

Type:

Koc

Value:

11.5 other: Cm3g-1

Adsorption coefficient 10

Sample No.:

#5

Type:

Koc

Value:

77.8 other: Cm3g-1

Results: Batch equilibrium or other method

Adsorption and desorption constants:

The results of adsorption isotherms experiments show the Freundlich adsorption coefficient ( KFads) values in five soils (A, B, C, D, E) are 1.42, 0.173, 1.65, 0.727 and 7.23 μg^(1-1/u) cm^3^(1/n) g^-1 respectively. The 1/n values for different soils were 0.759, 0.882, 0.910, 0.574 and 0.793, respectively

The Freundlich desorption coefficient ( KFdes) values inthree soils (A, C, E) are 2.00, 4.07 and 19.2 μg^(1-1/u) cm^3^(1/n) g^-1 respectively, the 1/n values fordifferent soils were 0.964, 0.760 and 0.502 respectively

Recovery of test material:

The recoveries of the test substance from the whole. test procedure were 95.7%, 90.8%, 93.7%, 88.8% and 90.9% in soils A, B, C, D, E, respectively

Concentration of test substance at end of adsorption equilibration period:

Given in Table 8.

Concentration of test substance at end of desorption equilibration period:

Given in Table 10.

Mass balance (%) at end of adsorption phase

Mass balance (%) at end of adsorption phase 1

Sample no.:

#1

Duration:

48 h

Remarks on result:

other: Given in Table 12, not as percent

Mass balance (%) at end of adsorption phase 2

Sample no.:

#2

Duration:

48 h

Mass balance (%) at end of adsorption phase 3

Sample no.:

#3

Duration:

48 h

Mass balance (%) at end of adsorption phase 4

Sample no.:

#4

Duration:

48 h

Mass balance (%) at end of adsorption phase 5

Sample no.:

#5

Duration:

48 h

Mass balance (%) at end of desorption phase

Mass balance (%) at end of desorption phase 1

Sample no.:

#1

Duration:

48 h

Mass balance (%) at end of desorption phase 2

Sample no.:

#2

Duration:

48 h

Remarks on result:

not determinable

Mass balance (%) at end of desorption phase 3

Sample no.:

#3

Duration:

48 h

Mass balance (%) at end of desorption phase 4

Sample no.:

#4

Duration:

48 h

Remarks on result:

not determinable

Mass balance (%) at end of desorption phase 5

Sample no.:

#5

Duration:

48 h

Transformation products:

no

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

According to the above results, the Kd values in five soil types were 0.53, 0.088, 1.68, 0.16 and 5.33 cm3 g-1, respectively. The Koc values in the five soil types were 8.12, 6.47, 31.3, 11.5 and 77.8 cm3 g-1. The average Koc values oftest substance was 27.0 cm3 g-1.The Freundlich adsorption coefficient ( Kfads) values in five soils (A, B, C, U, E) are 1.42, 0.173, 1.65, 0.727 and 7.23 μg^(1-1/u) cm^3^(1/n) g^-1 respectively. The 1/n values for different soils were 0.759, 0.882, 0.910, 0.574, 0.793
for A, B, C, D, E soil respectively. The recoveries of the test substance from the whole test procedure were 95.7%, 90.8%, 93.7%, 88.8% and 90.9% in soils A, B, C, D, E, respectively.