German to English Science Chemistry; Chem Sci/Eng Product recovery after diafiltration

I have been translating a number of buffer manufacturing protocols for chromatography and related texts. I have come across the German words Ankonzentration and ankonzentrieren several times but cannot find translations for them. Linguee just translates them as concentration/concentrate. Is this adequate?
One section of the texts is dealing with product recovery after TFF. The protein is concentrated to its maximum concentration and then there is a heading saying Ankonzentrieren Produkt:
Vor Start ist die abzuführende Permeatmenge für die Ankonzentrierung und das berechnete Endvolumen... in der Phase einzugeben.