Specific migration is a term that indicates the amount of a particular ingredient that can pass from food contact materials (eg, food packaging) to the foodstuff. Total migration refers to the total migration of all components while specific migration focuses on a particular component.

For example, a plasticizer or an additive used in a plastic packaging material may migrate from the food contact material to the food. In this case, specific migration testing is done to determine how much of this specific ingredient is passed into the food.

**How is the Specific Migration Test Performed?**

1. **Sample Preparation:** The packaging material to be tested is sampled.

2. **Simulant Selection:** Simulants are also used in specific migration tests. However, these simulants are chosen to assess the migration of the specific component.

3. **Incubation:** The packaging sample is left in contact with the simulant at a specified temperature and time.

4. **Analysis:** After the incubation period, the specific migrant substance contained in the simulant is analyzed. This analysis is usually done by gas chromatography (GC), liquid chromatography (LC) or other analytical methods.

5. **Evaluation of Results:** Analysis results are compared with the determined limits. These limits are determined by national or international regulations according to the specific component.

**What is Content?**

Content generally refers to the composition of a material or product. The content of food packaging or other materials is defined as the list of ingredients contained in that material or product. Content information provides information about the safety, suitability and quality of the product.

The contents of a package may contain polymers, plasticizers, colorants, stabilizers and other additives used in the production of that package. The content is usually specified in documents such as the product label, technical data sheet or safety data sheet.

In summary, specific migration measures the passage of a particular ingredient into food, while ingredient refers to the composition of a material or product. Both concepts provide important information regarding the safety and quality of products and materials.