Formaldehyde derivatization, a Side Reaction During Filter-Aided Sample Preparation

The filter-aided sample preparation (FASP) method has been commonly used for proteomic sample preparation due to its high efficiency and convenience. Herein, we report an overlooked side reaction during FASP method, resulting in a mass increment of 12 Da. We confirmed that the side reaction is caused by formaldehyde released from the spin filter and devel-oped a pretreatment step to reduce the side reaction. We further examined spin filters from different vendors and offered suggestions for different experimental purpose. Our findings would benefit the deep screening of labeling proteomics analy-sis and offer a new direction to improve performance of filter devices used for different biological and proteomics studies.