Rodenticide–humic acid adsorption mechanisms and role of humic acid on their toxicity on human keratinocytes: chromatographic approach to support the biological data

Humic substances are the most important soil components affecting the behaviour and performances of herbicides in the soil–water–organism system. In this paper, a chromatographic approach was used for analysis of anticoagulant rodenticide–humic acid adsorption mechanisms. Using an equilibrium perturbation method, it was clearly shown that: (i) humic acid can be adsorbed on the C18 stationary phase, and (ii) all the rodenticides can be adsorbed on the humic acid adsorbed on the C18 stationary phase. This approach allowed the determination of the adsorption constant values between the anticoagulant rodenticides and humic acid as well as the corresponding thermodynamic data of this adsorption mechanism. The role of humic acid on the toxicity of these rodenticides on human keratinocytes was also clearly described in relation to these physico-chemical data.