Automatic filtration and filter flush for robust online solid-phase extraction liquid chromatography

Online solid-phase extraction-liquid chromatography (SPE-LC) with microbore or capillary columns was significantly improved regarding robustness, as an easily installed automatic filtration and filter flushing (AFFL) procedure was added to avoid system clogging. Specifically, an injected sample is passed through a union containing a stainless steel filter prior to SPE trapping. The filter stops any particulate matter from reaching the SPE. When the SPE is subsequently connected to the LC column by column switching, a separate pump backflushes the filter-union, removing the particulate matter off the filter after each injection. This feature greatly reduced backpressure buildup over the entire system.