Reaction mass of 2-ethylhexyl (3-isocyanato-4-methylphenyl)carbamate and 2-ethylhexyl (5-isocyanato-2-methylphenyl)carbamate and 2-ethylhexyl (3-isocyanato-2-methylphenyl)carbamate

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 24, 2018 to October 23, 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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))

Version / remarks:

Organisation for Economic Cooperation and Development. 2001. OECD Guideline for Testing of Chemicals, 121: Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge using High Performance Liquid Chromatography

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

Version / remarks:

Annex to Commission Directive 2001/59/EC. 2001. Estimation of the Adsorption Coefficient (KOC) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC). Official Journal of the European Communities No. L225, Method C.19.

Deviations:

not specified

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

soil

Specific details on test material used for the study:

No further details specified in the study report.

Radiolabelling:

no

Test temperature:

COLUMN TEMPERATURE: 40.0°C

Details on study design: HPLC method:

EXPERIMENTAL DESIGN
In this experiment, the interaction of the test substance containing polar and/or non-polar functional groups with a dual composition (polar and non-polar sites) HPLC stationary phase mimicked the interaction of the test substance with organic matter present in soil and sludge matrices. The HPLC method was applicable to the test substance since an appropriate detection system (e.g. UV absorbance) was available and the test substance did not react with either the eluent or the stationary phase. The test substance met the other applicability criteria specified in the study protocol for use of the HPLC-estimation method. For a given mobile phase composition and pH, capacity factors were calculated for reference standards of known log KOC using urea to estimate column dead time (i.e., the retention time of an unretained organic compound). The logarithms of the calculated capacity factors were then plotted against published log KOC values to establish a linear regression equation.
One solution of Trixene AS was prepared in 55% Methanol (MeOH): 45% reagent H2O v/v at a nominal concentration of 25.0 mg/L. The test substance solution was prepared from a freshly prepared stock solution in MeOH. Six reference standards were prepared in the respective mobile phase at a nominal concentration range (5.00 to 300 mg/L) selected to provide desired ultraviolet (UV) detector response. Of these reference substances, one was used for dead time determination and the other five had known log KOC values given in the OECD 121 guideline and were used as calibration standards. The reference standard preparations were sequentially injected into an HPLC system followed by triplicate injections of the test substance preparation. The calibration reference standards injection sequence was repeated following the test substance injections. The HPLC system was operated under standardized isocratic, reverse-phase operating conditions per the guideline.

Mobile Phase Preparation
The mobile phase was prepared by combining 550 mL of methanol with 450 mL of reagent water in a glass bottle. The HPLC mobile phase composition was 55% MeOH: 45% reagent water (v/v) as specified in the guideline. An aliquot of the eluent leaving the analytical column was collected under the guideline condition of 55:45 (v/v) MeOH: reagent water and the pH was measured. The pH of the mobile phase flowing through the column was determined to be 5.

Reference Stocks and Standards Preparation
A primary stock of each reference substance was prepared in either ACN or MeOH. An appropriate amount of each reference stock was fortified into separate 10.0-mL volumetric flasks preloaded with 4.5 milliliters of reagent water and was brought to a 10.0 milliliters final volume with MeOH. The reference standard solutions yielded a final solution composition of 55% MeOH: 45% reagent water (v/v), and the selected standard nominal concentrations gave an appropriate detector response for each reference substance.
Since the test material is known to hydrolyze quickly based on discussions with the Sponsor, the Log KOC of a reference material consisting of the hydrolysis products of the test material, Trixene AS, was determined in a similar manner as the test material. A primary stock solution of the reference material was prepared at a nominal concentration of 1.00 mg/mL by accurately weighing 0.1000 g of the reference material into a 100 mL volumetric flask and bringing to volume with MeOH. A single subsample of the stock preparation was prepared at a nominal concentration of 50.0 mg/L for analysis by fortifying an appropriate amount (500 μL) of the primary stock into a 10.0 mL volumetric flask, preloaded with 4.50 mL of reagent water. The volumetric flask was then brought to final volume with MeOH. An aliquot of the final volume from the reference material solution was transferred to and sealed in an autosampler vial and submitted for HPLC/UV analysis. Each of the solution injections (10.0 μL) gave an acceptable UV response.

Test Solution Preparation
A primary stock solution of Trixene AS was prepared at a nominal concentration of 1.00 mg a.i./mL by weighing 0.1003 g of the test substance into a beaker and quantitatively transferring into a 100-mL volumetric flask. The volumetric flask was then brought to final volume with MeOH. One subsample of the stock solution was prepared at a nominal concentration of 25.0 mg a.i./L for analysis by fortifying an appropriate amount (0.250 mL) of the primary stock into separate 10.0 mL volumetric flasks pre-loaded with 4.50 mL of reagent water. The volumetric flask was then brought to final volume with MeOH. Three aliquots of the final volume from the test solution was transferred to and sealed in autosampler vials and submitted for HPLC/UV analysis. Each of the solution injections (10.0 μL) gave an acceptable UV response at 210 nm.

Test Procedure
Retention times of the test substance and reference substances were determined using an Agilent Series 1100 High Performance Liquid Chromatograph (HPLC) equipped with an Agilent Series 1100 variable wavelength UV detector. Chromatographic separations were achieved using an Agilent Technologies InfinityLab Poroshell 120 EC-CN analytical column (100 mm x 3.0 mm, 2.7-μm particle size). The column temperature was maintained at 40°C. The flow rate was 0.500 mL/minute. Prior to test substance analyses, the dead time was determined by injecting the urea reference standard.
For each analytical sequence, the set of six reference standards (including urea) were injected prior to and after the test substance injections to determine retention times. All injection volumes were 10.0 μL. The test substance solutions were analyzed under the same chromatographic conditions as for the reference standard solutions. All of the standards and samples were analyzed at 210 nm.

Data Analysis
For each analytical sequence, the capacity factor (k), was calculated for the test substance and each reference substance using the following equation:
k = (tR – t0)/t0
where tR was the retention time of the test substance or reference substance and t0 was the column dead time established with urea. A correlation graph of Log k versus Log KOC for the reference standards was plotted and fitted to a regression equation in the form y = mx + b. Log KOC values for each test substance peak were calculated by substituting the calculated logarithm of the capacity factor for the test substance peak into the linear regression equation for the applicable calibration curve.

Key result

Type:

log Koc

Value:

3.38 dimensionless

Temp.:

40 °C

Remarks on result:

other: pH, % Org. Carbon & Matrix not specified

Key result

Type:

log Koc

Value:

3.78 dimensionless

Temp.:

40 °C

Remarks on result:

other: pH, % Org. Carbon & Matrix not specified

Key result

Type:

log Koc

Value:

3.99 dimensionless

Temp.:

40 °C

Remarks on result:

other: pH, % Org. Carbon & Matrix not specified

Key result

Type:

log Koc

Value:

> 5.63 dimensionless

Temp.:

40 °C

Remarks on result:

other: pH, % Org. Carbon & Matrix not specified

Details on results (HPLC method):

A total of six reference substances were prepared and injected in duplicate (once at the beginning and once near the end of the HPLC sequence). The retention times for one of the reference substances, urea, was used to determine the HPLC system dead time (t0) for use in calculating capacity factors (k) of the remaining reference substances and the test substance. The mean retention time of the duplicate urea standard injections was 1.017 minutes.
Five additional reference substances were analyzed. The capacity factors of all the reference substances were calculated based upon their retention times.
Before the injection of the reference standards, an injections of a reagent blank solution (55% MeOH: 45% reagent water (v/v)) showed that the reagents used were free of any contaminants and confirmed the peak retention assignments for the reference substances.
The 25.0 mg/L Trixene AS solutions were sequentially injected. Trixene AS eluted as four peaks on the UV detector. The mean retention times of the peaks were 2.13, 2.50, 2.76, and 8.99. The corresponding Log KOC values for the test substance peaks were 3.38, 3.78, 3.99, and >5.63 (6.07 extrapolated). Since the test material is known to hydrolyze quickly based on discussions with the Sponsor, the Log KOC of a reference material consisting of the hydrolysis products of the test material, Trixene AS was determined in a similar manner as the test material.

Reference Standards Retention Times, Capacity factors, and Log Koc Values

Reference Standard	Concentration (mg/L)	Retention Time (minutes)	Capacity Factor (k)^1,2	Log k^2	Log Koc
Urea	300	1.016 1.017	N/A	N/A	N/A^3
Acetanilide	20.0	1.224 1.225	0.204 0.205	-0.690 -0.688	1.25^3
Phenol	25.0	1.269 1.269 1.266	0.248 0.248 0.245	-0.605 -0.605 -0.610	1.32^3
Naphthalene	5.00	1.850 1.846	0.820 0.816	-0.0862 -0.0883	2.75^3
Phenanthrene	5.00	2.783 2.789	1.74 1.74	0.240 0.241	4.09^3
4,4’-DDT	50.0	6.656 6.641	5.55 5.53	0.744 0.743	5.63^3
^1Capacity factor (k) is the standard retention time minus the mean column dead time (1.017 minutes for urea) divided by the mean column dead time. ^2Values obtained utilizing Microsoft® Excel 2010 in full precision mode. Manual calculations may differ slightly. ^3Log Koc values are based on literature values provided in OECD Guideline 121.

 

Log Adsorption Coefficients (Log Koc) Based on UV Data for the Test Substance

Sample Number (796K-104-)	Peak Assignment	Retention Time (minutes)	Mean (ẋ) Standard Deviation (SD)^1	Capacity Factor (k)^1,2	Log k^1	Log Koc^1 (extrapolated)	Mean (ẋ) Standard Deviation (SD)^1,3
2	1	2.128 2.131 2.133	ẋ = 2.131 SD = 0.003	1.09 1.10 1.10	0.0388 0.0400 0.0408	3.38 3.38 3.38	ẋ = 3.38 SD = 0.003
2	2	2.501 2.504 2.508	ẋ = 2.504 SD = 0.004	1.46 1.46 1.46	0.164 0.165 0.167	3.77 3.78 3.78	ẋ = 3.78 SD = 0.003
2	3	2.756 2.760 2.764	ẋ = 2.760 SD = 0.004	1.71 1.72 1.72	0.233 0.234 0.235	3.99 3.99 4.00	ẋ = 3.99 SD = 0.003
2	4	8.988 8.970 9.001	ẋ = 8.986 SD = 0.016	7.84 7.82 7.85	0.894 0.893 0.895	>5.63 (6.07) >5.63 (6.07) >5.63 (6.08)	ẋ = >5.63 SD = N/A
^1Values obtained utilizing Microsoft® Excel 2010 in full precision mode. Manual calculations may differ slightly. ^2Capacity factor (k) is the sample retention time minus the mean column dead time (1.017 minutes for urea) divide by the mean column dead time. ^3N/A = Not Applicable.

 

Validity criteria fulfilled:

yes

Conclusions:

Under the chromatographic conditions specified, the test substance eluted as four peaks. The corresponding mean adsorption coefficients (Log KOC) for the test substance were 3.38, 3.78, 3.99, and >5.63.

Executive summary:

Trixene AS: Estimation of Adsorption Coefficient Using High Performance Liquid Chromatography (HPLC).

TEST SUBSTANCE: Trixene AS

TEST SYSTEM: Analytical Column: Aglient Technologies InfinityLab Poroshell 120 EC-CN (100 X 3.0 mm, 2.7-µm). Mobile Phase: Methanol: Reagent Water, 55:45 v/v

SUMMARY: Under the chromatographic condition specified, the test substance eluted as four peaks on the ultraviolet (UV) detector. The corresponding adsorption coefficients (Log Koc) for the test substance were 3.38, 3.78, 3.99 and >5.63.

Description of key information

Under the chromatographic condition specified, the test substance eluted as four peaks on the ultraviolet (UV) detector. The corresponding adsorption coefficients (Log Koc) for the test substance were 3.38, 3.78, 3.99 and >5.63.

Key value for chemical safety assessment

Koc at 20 °C:

5.63

Additional information

Trixene AS: Estimation of Adsorption Coefficient Using High Performance Liquid Chromatography (HPLC).

TEST SUBSTANCE: Trixene AS

TEST SYSTEM: Analytical Column: Aglient Technologies InfinityLab Poroshell 120 EC-CN (100 X 3.0 mm, 2.7-µm). Mobile Phase: Methanol: Reagent Water, 55:45 v/v

SUMMARY: Under the chromatographic condition specified, the test substance eluted as four peaks on the ultraviolet (UV) detector. The corresponding adsorption coefficients (Log Koc) for the test substance were 3.38, 3.78, 3.99 and >5.63.