Development of a fast LC-MS/MS protocol for combined measurement of six LSDs on dried blood spot in a newborn screening program.

New treatment options and improved strategies for Lysosomal Storage Disorders (LSDs) diagnosis on dried blood spot (DBS) have led to the development of several pilot newborn screening programs. Building on a previously published protocol, we devised a new 6-plex assay based on a single DBS punch incubated into a buffer containing a combination of substrates (GAA, GLA, ASM, GALC, ABG and IDUA). This new protocol incorporates a new trapping and clean-up procedure using perfusion chromatography connected on-line with an analytical column for analyte separation, after enzymatic reaction. Results are available after 4.5 min. Several incubation times were tested in order to reduce sample preparation times and to improve accuracy and reproducibility, also regarding the quenching of the reaction within the time window of linear product accumulation. The collected data demonstrate that an incubation time of 4 h is enough to achieve good reaction efficiency without any impact on sensitivity. The method proved versatile and robust for various instrument configurations. The fast sample preparation and running times allow a high sample throughput; an advantage in newborn screening procedures. This method can also be used for diagnostic purposes, allowing a rapid diagnosis in a few hours.