The Whatman™ FF High Performance (HP) membrane is a diagnostic membrane that enables line separation and reproducible results for the detection of target molecules in liquids such as water, urine, blood, and saliva. The target molecules may include drugs, hormones, proteins, antibodies, nucleic acids, whole bacteria, and viruses. The FF HP membrane is suitable for use in lateral flow assay manufacture. It is produced using a casting method to yield a uniform, powder-free surface that can deliver a coefficient of variation in capillary rise of <10%. Its reproducibility can improve the consistency of assays and offer a reliable limit of detection.