Clorofene

Adsorption / desorption

Description of key information

Koc: 2511 (OECD 121, Jungheim, 2006)

log Koc: 3.43 (OECD 121, Jungheim, 2006)

Key value for chemical safety assessment

Koc at 20 °C:

2 511

Additional information

The adsorption coefficient Koc of Chlorophene (CAS 120-32-1) was estimated on soil via a screening test (A) and a test design with four different soil types (B).

A) Screening test

The adsorption coefficient Koc of chlorophene on soil was estimated using HPLC (Jungheim, R., 2006). The test was performed according to OECD guideline 121 (Proposal for New Guideline, 2001). Six reference standards of known Koc were analysed on a HPLC system to determine an average capacity factor k’. Sodium nitrate was used to determine the HPLC system dead time (t0). A regression curve was plotted, with determined k’ values and the known Koc values (log k’ versus log Koc). Chlorophene was analysed on the same HPLC system during the same sample sequence as the reference substances. The Koc value for chlorophene was estimated by interpolation from the reference substance regression line. The estimated Koc value for chlorophene is log 3.43 (Koc = 2511), (Jungheim, 2006) and summarised in Table 1.

Table 1: HPLC retention time data and Koc calculations for chlorophene and reference substances obtained in an OECD screening test (Jungheim, 2006)

Calibration substance	Retention time [tr] = min*	Capacity factor k’*	Log k’*	Log Koc
2-Nitrobenzamide	5.535	0.678	- 0.169	1.45
3-Nitrobenzamide	5.680	0.722	- 0.141	1.95
3,5-Dinitrobenzamide	6.018	0.824	- 0.084	2.31
Triazoxide	7.389	1.240	0.093	2.44
Naphthalene	8.276	1.509	0.179	2.75
Phenanthrene	9.550	1.896	0.278	4.09
Chlorophene (Test item)	8.532	1.587	0.201	3.43

* mean value from 3 single values

B) Adsorption and desorption in at least three soil types

Aqueous solutions of Chlorophene were equilibrated with four soil types and the adsorption and desorption coefficients and constants were determined (Meinerling, M., 2007). The concentration of the test item was determined using HPLC method. The experiment was conducted according to OECD Guidelines for Testing of Chemicals, Guideline No. 106 and Commission Directive 2001/59/EC, Method C.18. No relevant deviations from the guidelines occurred.

In the screening test the adsorption kinetics were estimated at one concentration of the test item using four soil types. The percentage of adsorption was calculated after different time intervals. The equilibrium was reached after 24 h incubation time. The percent adsorbed was within 20% to 80% range.The calculated distribution coefficient was in the range of 16 to 98 mL/g. The corresponding adsorption coefficient was in the range from 1361 to 2974 mL/g. Desorption was estimated at one concentration of the test item using 4 different soil types. The desorption of the adsorbed test item after 24 h from the different soil types ranged from 18% up to 39% desorption. The Freundlich adsorption coefficients (KF ads values) varied between 7.8 and 41.6 mL/g. Related to organic carbon, adsorption coefficients between 650 and 1484 mL/g have been calculated. Freundlich coefficients determined for the desorption (KF des values) were lower as those determind for the adsorption (range of KFdes: 0.0-0.6 mL/g). Results are summarized within Table 2.

Table 2: Summary of Results

Soil description	% org C	Time to reach Ads.Equilibrium [h]	Adsorption(1) [%]	Distribution1 Coefficient Kd [mL/g]	Adsorption1 Coefficient Koc [mL/g]	Freundlich Intercept	Adsorption Isotherm Slope	Freundlich Ads. Coeff KFads [mL/g]	Freundlich Ads.Coeff KFoc [mL/g]
Lufa 2.1 -sand	1.2	24	38.4	15.7	1360.9	0.89	1.163	8	650
Lufa 2.2 – loamy sand	2.4	24	64.4	52.9	2239.4	1.48	1.148	30	1263
Lufa 6S –clayey loam	1.8	24	60.9	40.4	2205.0	1.43	1.097	27	1484
Eurosoil3 –loam	3.3	24	79.2	98.2	2974.2	1.62	1.261	42	1260

Mean value calculated from exact raw data

(1): calculated from adsorption kinetic experiment

[LogKoc: 3.4]