For China new chemical notification, as an important Environmental behavior parameter, adsorption /desorption studies are used in environmental quantitative risk assessment, which is bonding capability between the substance and a soil surfaces parameter, furthermore, it is data necessary requirement for regular chemical notification (≥Level I, which is above 10 tons per year). In China Guidelines for the Testing of Chemicals-Physical-Chemical Properties and Physical Hazard Volume, below testing methods were provided:
1. Batch Equilibrium Method (OECD 106) uses several typical soils to determine the distribution coefficient which is the ratio between the content of substance in the soil phase and the mass concentration of the substance in the aqueous solution and the organic carbon normalized adsorption coefficient Koc that relates the Kd to the content of organic carbon of the soil. Generally, direct method and indirect method will be selected.
2. HPLC Method (OECD 121) measures the log Koc with the retention time on the reverse phase column via the calibration with reference substances.
In  accordance with date requirements of China notification, OECD 106 is preferred method for adsorption /desorption study. Only when OECD 106 cannot be carried out, HPLC Method (OECD 121) can be used as an alternative. This is different from the requirement of REACH, where HPLC Method is widely adopted. And questions are frequently asked by dossier review experts regarding the reasons for choosing HPLC Method. Each method has its own advantages and disadvantages, and whether OECD 121 can be recognized by experts depends on how to address the special properties of the testing substance scientifically. Insolubility alone is not solid enough. More substance properties and testing factors have to be taken into consideration for a statement in order to convince experts OECD 121 testing is the appropriate method to evaluate the adsorption /desorption of the notified substance.