Global and specific migration

What is a global migration test in simulants? (Standard NF EN 1186)

According to standard NF EN 1186, in a global migration test, the analytical laboratory determines the mass of all migrating products, without differentiating their nature.
The results obtained are expressed in mg/kg of foodstuffs or in mg/dm² of material.

How is the overall migration test carried out? 

The sample is weighed and then placed in contact with the simulant under defined test conditions (time and temperature). The volume of simulant and the sample's contact surface are known. 
At the end of the test, the simulant is evaporated and the sample weighed again. 
The difference in weight indicates the amount of substance released after overall migration, expressed in mg / dm² of packaging. 
The overall migration limit is 10 mg/dm².

What is specific migration? (NF EN ISO 13130 standard)

For these tests, the laboratory targets certain defined substances.
Results are expressed in mg target molecule/kg foodstuff.

How does the specific migration test work? 

Based on the same principle as global migration, here the search is targeted and known in advance. The aim is to quantify a substance whose use is authorized by EU regulation 10/2011, but whose migration must not exceed a certain limit (SML or specific migration limit) expressed in mg/kg (mg of substance/kg of food or simulant).
Bisphenol A, PFAS, MOSH/MOAH, formaldehyde, etc. are often tested for.

Migration analyses (overall and specific) are used to check compliance of tested products with European regulations on products in contact with foodstuffs.