Charcoal

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-08-03 to 2010-08-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted in accordance OECD no. 121 resp. EU method C.19

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Test guideline 1

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))

Deviations:

no

Test guideline 2

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))

Deviations:

no

Principles of method if other than guideline:

HPLC is performed on analytical columns packed with a commercially available cyanopropyl solid phase containing lipophilic and polar moieties. A moderately polar stationary phase based on a silica matrix is used. While passing through the column along with the mobile phase the test substance interacts with the stationary phase. As a result of partitioning between mobile and stationary phases the test substance is retarded. The dual composition of the stationary phase having polar and non-polar sites allows for interaction of polar and non-polar groups of a molecule in a similar way as is the case for organic matter in soil or sewage sludge matrices. This enables the relationship between the retention time on the colum and the adsorption coefficient on organic matter to be established.

GLP compliance:

no

Type of method:

HPLC estimation method

Media:

other: no aplicable

Test material

Test material information

Constituent 1

Reference substance name:

Charcoal

EC Number:

240-383-3

EC Name:

Charcoal

Cas Number:

16291-96-6

IUPAC Name:

Carbón vegetal

Details on test material:

Name: Charcoal (Probe 2: C-Fix =80.5%)
Batch no.: 29004
Appearance: Charcoal typic
Composition: Charcoal
CAS no.: 16291-96-6
EINECS-no.: 240-383-3
Purity: C-Fix: 80.5%
Expiry date: Dec. 2030
Storage: Room temperature 20 ± 5 °C, keep away from humidity

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
no aplicable

Radiolabelling:

no

Study design

Test temperature:

25±1°C

HPLC method

Details on study design: HPLC method:

Pump: Dionex P580 Pump
Injector: Rheodyne 8125)
Column: Reprosil-Pur CN Dr. Maisch, 4.6 mm i.D., 125 mm length, particle size 3 µm
Detector: Dionex, UVD 170S
Column temperature was room temperature, 25 ± 1 °C.
Wavelength for evaluation: 220 nm
Mobile phase: Methanol/water (55/45% v/v)

Batch equilibrium or other method

Analytical monitoring:

not required

Details on sampling:

no aplicable

Details on matrix:

no aplicable

Details on test conditions:

no aplicable

Results and discussion

Adsorption coefficient

Type:

log Koc

Value:

< 1.5

Temp.:

25 °C

Results: HPLC method

Details on results (HPLC method):

The log KOC-value of the test item charcoal (Probe 2: C-Fix = 80.5%) lies outside the calibration range obtained with the used reference substances (1.32-5.63) and also outside the determinable log Koc-range of the HPLC screening method (according to OECD guideline 121: 1.5 - 5.0). Therefore, the log KOC of the test item should be stated as < 1.5.

Results: Batch equilibrium or other method

Adsorption and desorption constants:

no aplicable

Recovery of test material:

no aplicable

Concentration of test substance at end of adsorption equilibration period:

no aplicable

Concentration of test substance at end of desorption equilibration period:

no aplicable

Details on results (Batch equilibrium method):

no aplicable

Statistics:

no aplicable

Any other information on results incl. tables

Calculation of the capacity factor k’:

The capacity factor k´ for every peak was calculated as follows:

 

k' = (t_R - t₀)/t₀ 

with   t_R        retention time

           t_o       dead time (retention time of sodium nitrate)

Calibration log k’ vs. log K_OC

The calibration function was drawn up from the six measurements of the capacity factors of the reference items. By plotting the (known) log K_OC values of the reference items against the mean log capacity factors and performing linear regression, a calibration function was obtained in the following form:

y = ax + b

Calculation of log K_OC:

Using the determined equation of linear regression and the calculated capacity factors for the test item, for each of the three measurements the log K_OC was calculated.

Finally, mean and standard deviation of the log K_OC were calculated.

Equation of the regression line:

log k’ = 0.2934 * log K_OC– 0.32 
with a correlation coefficient r²   = 0.986.

Test item charcoal (Probe 2: C-Fix =80.5%):

Measurement data

The retention times of the peak obtained after injection of the test item solution are presented in the following table:

Retention times - test item

Peak Test Item	TR
	[min]
Measurement 1	2.270
Measurement 2	2.256
Measurement 3	2.236
Mean	2.254
Standard deviation	0.017

 

Calculated values:

Capacity factor k’, log k’, and log K_OC- test item

Peak Test Item	k’	logk’	log KOC
Measurement 1	0.7606	-0.1188	0.686
Measurement 2	0.7497	-0.1251	0.664
Measurement 3	0.7342	-0.1342	0.633
Mean			0.661
Standard deviation			0.026

 

log K_OCwas calculated from the capacity factor k’ as follows:

 

log K_OC= (log k’ + 0.32) / 0.2934

Applicant's summary and conclusion

Validity criteria fulfilled:

no

Remarks:

no log Koc values of test item are outside the range of calibration

Conclusions:

The log Koc of the test item charcoal (Probe 2: C-Fix = 80.5%) is stated as <1.5.