Are HEPES, MOPS and PIPES buffers compatible with QIAGEN's PhosphoProtein Purification kit?

No, these buffers are not recommended for use with the PhosphoProtein Purification Kit. The PhosphoProtein Lysis Buffer supplied in the kit is essential for optimal binding conditions of phosphoproteins to the purification columns. If other lysis buffers must be used, we recommend to dialyse the samples against the PhosphoProtein Lysis Buffer, which can be ordered separately (1000 ml) using catalogue number 1031358.

Alternatively, you can also dilute your lysed sample 1:10 with the PhosphoProtein Lysis Buffer before loading the column.