Inter-laboratory evaluation of instrument platforms and experimental workflows for quantitative accuracy and reproducibility assessment

•Reproducibility of MRM with SIS peptides for plasma protein quantitation was studied.•This was an international study featuring 16 laboratories and 19 LC–MS/MS platforms.•The 3 evaluated kits were designed for platform and/or workflow evaluation.•For qualified peptides, instrument type did not affect the quality of the results.•Technician skill was a factor, as well as sub-optimal LC–MS performance.•This study emphasized the importance of proper training and routine quality control.

The reproducibility of plasma protein quantitation between laboratories and between instrument types was examined in a large-scale international study involving 16 laboratories and 19 LC–MS/MS platforms, using two kits designed to evaluate instrument performance and one kit designed to evaluate the entire bottom-up workflow. There was little effect of instrument type on the quality of the results, demonstrating the robustness of LC/MRM-MS with isotopically labeled standards. Technician skill was a factor, as errors in sample preparation and sub-optimal LC–MS performance were evident. This highlights the importance of proper training and routine quality control before quantitation is done on patient samples.

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