The adsorption/desorption characteristics of [test material] was studied in a (a) – (texture) soil(s) [pH --, organic carbon -- %] from [Country] in a batch equilibrium experiment.  The experiment was conducted in accordance with the – (specify the Guideline followed), and in compliance with the – GLP standard (specify the GLP standard(s) followed e.g., OECD-GLP).  The adsorption phase of the study was carried out by equilibrating air-dried/fresh soil with [test material] at 0, x1, c2, --, and Xn mg a.i./kg soil in dark at -- ēC for – hr.  The equilibrating solution used was 0.01 M CaCl2/other, with a soil/solution ratio of --.  Desorption phase of the study was carried out by – [Describe the desorption method including the number of desorption cycles used].

 

The supernatant solution after adsorption and desorption was separated by centrifugation/other and, extracted with – (specify the solvent and/or method used; indicate if the supernatant was not extracted), and the [test material] residues were analysed by – [TLC/HPLC – (detector)/GC-(detector)].  [Indicate whether 14C in the soil residue after the adsorption and desorption steps was determined by combustion].  The adsorption parameters were calculated using the Freudlich adsorption isotherm.

 

[Indicate the stability of [test material] during the adsorption/desorption phase of the experiment].  The mass balance at the end of adsorption phase of the study was – and -- % of the applied in soil 1 and soil 2, respectively.  The mass balance at the end of desorption phase was – and -- % of the applied in soil 1 and soil 2, respectively.

 

After – hr of equilibration, and – and -- % of the applied [test material] was adsorbed in soil 1 and soil 2, respectively.  The adsorption Kd or K values were – and – in soil 1 and soil 2, respectively.  The adsorption Koc values ranged from – to --.  At the end of the desorption, -- and -- % of the adsorbed amount was desorbed in soil 1 and soil 2, respectively.  The desorption Kd or K values were -- and –, in soil 1 and soil 2, respectively. Kd or K and Koc values were higher/similar/lower than those obtained for adsorption.

 

Results Synopsis:

 

Soil type:

Amount adsorbed:             as % of the applied – (range)

Adsorption Kd:

Adsorption Koc:

Amount desorbed:             as % of the adsorbed – (range)

Desorption Kd:

Desorption Koc:

 

Study Acceptability:  This study is classified [acceptable/unacceptable/supplemental] and satisfies/does not satisfy the guideline requirement for an adsorption/desorption study in soil.