Disodium 2-(2,4,5,7-tetrabromo-6-oxido-3-oxoxanthen-9-yl)benzoate

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Experimental test result performed using standard test guidelines

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))

Principles of method if other than guideline:

To determine Adsorption coefficient (KOC) on soil and on sewage sludge of the test chemical using HPLC.

GLP compliance:

no

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Radiolabelling:

not specified

Test temperature:

25°C

Details on study design: HPLC method:

HPLC Procedure:
The solutions of the test substance and reference substances were prepared in solvent mentioned in 4.3. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(table 3).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor.

Operating Conditions:
HPLC Model No. : Agilent Technologies,1260 Infinity
Flow Rate : 1.0ml/min
Column : ZORBAX Eclipse Plus C18, 4.6×100mm, 3.5 μm
Mobile phase : ACN : water (55:45)
Temperature : 25°C
Detector : Diode Array Detector @210nm
Injector : Autosampler
Injector volume : 10μl
Data Acquisition software : ChemStationOpen lab Control Panel

Analytical monitoring:

not specified

Details on sampling:

- Concentrations: 400 mg/l
- Sampling interval: A test item solution was prepared by accurately weighing 4 mg of test item and diluted with 5 ml water and make the volume with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 6.4.

Key result

Sample No.:

#1

Type:

log Koc

Value:

1.024 dimensionless

pH:

6.4

Temp.:

25 °C

Remarks on result:

other: logKoc was reported to be 1.024±0.010

Details on results (HPLC method):

The Adsorption coefficient (KOC) on soil and on sewage sludge of the test chemical was determined to be 1.024±0.010 at 25°C

Transformation products:

not specified

Test substance		K	LogK	Log Koc by Generalized Calibration Graph	Mean of Log Koc ± S.D.
tR1	0.963	0.086	-1.067	1.018	1.024±0.000
tR2	0.965	0.088	-1.056	1.031

Validity criteria fulfilled:

yes

Conclusions:

The Adsorption Coefficient of test chemical was determined as per the HPLC method (OECD Guideline-121). The Log Koc value was determined to be 1.024±0.010 at 25°C.

Executive summary:

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with 5 ml water and make the volume with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 6.4. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances were Acetanilide, Benzamide, 4-methylaniline(p-Tolouidine), Nmethylaniline, p-toluamide, Aniline, 2,5-Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4-Nitrobenzamide, 1-naphthylamine, 1-naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3 -trichlorobenzene, Pentachlorophenol, N,N-dimethylbenzamide, 3,5-dinitrobenzamide, phenanthrene, DDT having Koc value ranging from 1.25 to 5.63. The Log Koc value of test chemical was determined to be 1.024±0.010 at 25°C. This log Koc value indicates that the test chemical has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.

Description of key information

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with 5 ml water and make the volume with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 6.4. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances were Acetanilide, Benzamide, 4-methylaniline(p-Tolouidine), Nmethylaniline, p-toluamide, Aniline, 2,5-Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4-Nitrobenzamide, 1-naphthylamine, 1-naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3 -trichlorobenzene, Pentachlorophenol, N,N-dimethylbenzamide, 3,5-dinitrobenzamide, phenanthrene, DDT having Koc value ranging from 1.25 to 5.63. The Log Koc value of test chemical was determined to be 1.024±0.010 at 25°C. This log Koc value indicates that the test chemical has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.

Key value for chemical safety assessment

Koc at 20 °C:

10.568

Additional information

Various experimental key and supporting studies of the test chemical were reviewed for the adsorption end point which are summarized as below:

 

In an experimental key study from study report (2018),adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 4 mg of test item and diluted with 5 ml water and make the volume with Acetonitrile up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 6.4. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k(Annex - 2).The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances were Acetanilide, Benzamide, 4-methylaniline(p-Tolouidine), Nmethylaniline, p-toluamide, Aniline, 2,5-Dichloroaniline, 4-nitrophenol, 2 - nitrophenol, 2-nitrobenzamide, 3-nitrobenzamide, Nitrobenzene, 4-Nitrobenzamide, 1-naphthylamine, 1-naphtol, Direct Red 81, Benzoic acid methylester, Carbendazim, Benzoic acid phenylester, Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3 -trichlorobenzene, Pentachlorophenol, N,N-dimethylbenzamide, 3,5-dinitrobenzamide, phenanthrene, DDT having Koc value ranging from 1.25 to 5.63. The Log Koc value of test chemical was determined to be 1.024±0.010 at 25°C. This log Koc value indicates that the test chemical has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.

 

Another adsorption study (from peer reviewed journal Yi Wang et. al., 2006) was conducted for150 mins for evaluating the adsorption capacity of test chemical on anaerobic sludge. The study was performed using the batch equilibrium method under anaerobic conditions at a temperature of 38 °C and pH 7.0, respectively. Test chemical concentration used for the study was50 µmol/l. The anaerobic sludge used in this study was collected from a full-scale upflow anaerobic sludge blanket reactor treating citrate-producing wastewater in Bengpu, China. Prior to use, the sludge was first washed with tap water twice, and was then sieved to remove stone, sand and other coarse matters. Adsorption experiments were conducted using 250-ml screwtopped flasks to which 150 ml of dye-containing wastewater and biomass were added. One flask with dosage of dye solution but no biomass was used as control .Before shaking, nitrogen was sparged into the flasks and then the flasks were sealed with rubber plugs to ensure the anaerobic condition in the biosorption process. These flasks were then reciprocated in a water-bath shaker with a shaking rate of 150 rpm. Samples were taken at given time intervals and were then centrifuged at 12,000 rpm for 10 min. The supernatant was used for analysis of the residual test chemical concentration. Each run of the experiments was replicated at least three times. The concentrations of the test chemical was determined using a UV–vis spectrophotometer (UV751GD) at an absorbance wavelength of 516 nm. The concentration of volatile suspended solids (VSS) was measured according to the StandardMethods. Since anaerobic sludge has negative charges, the repulsive electrostatic interaction between test chemical with negative charges and sludge might be responsible for the lower adsorption density (q).Adsorption density (q) of the test chemical was determined to be 2.4 mg/g at a temperature of 38 °C. Anaerobic sludge had a much lower equilibrium adsorption density for test chemical. Based on this adsorption density, it indicates that test chemical has a low sorption and therefore have moderate migration to groundwater.

 

For the test chemical, adsorption experiment was conducted for evaluating the adsorption capacity of test chemical on Iraqi clay. Iraqi clay used in the study was obtained from river in Baghdad and supplied from general company of geological survey and mining Iraq. Soil was prepared by mechanical grinding and sieving to obtain a relatively narrow range of particles passing a no. 500 μm. After sieving Iraqi clay was washed with acidic solution then was washed with distilled water to remove dust and fines (impurities compounds), and dried to constant weight at 100°C.The adsorption isotherms have been determined by allowing eosin solution of known initial concentration to be mixed with accurately weighted amount of Iraqi clay in a tightly closed flask at a certain temperature and pH. The amount of Iraqi clay in the slurry has been 0.2 gm/10 ml solution. A constant mixing at a constant temperature and PH was achieved using a shaker water bath. The Iraqi clay–solution have been then equilibrated for two hours , clay suspensions have been then filtered and the supernatant solution was subjected to analysis using ultra violet –visible technique at (516)nm. Freundlich adsorption constant (Kf) of the test chemical was determined. The high Kf values indicate that the saturation time for adsorption of a test chemical is attained quickly due to high affinity of Iraqi clay towards adsorbate, while low Kf values indicate low adsorption rate of the test chemical. The Freundlich isotherm constant (Kf) value of the test chemical was determined to be 0.025, 0.024, 0.021 and 0.0152 at temperature 20.85 °C, 29.85 °C, 39.85 °C and 49.85 °C, respectively. This low kf indicates that the test chemical has a low adsorption to soil and therefore have moderate migration potential to ground water.

 

On the basis of above overall results for test chemical (from study report and peer reviewed journals), it can be concluded that thetest chemicalhas a negligible to low sorption to soil and sediment and therefore have rapid to moderate migration potential to ground water.