Updated project metadata. Data sets are used for benchmarking, pChem, a modification-centric, blind-search tool to provide a streamlined pipeline for unbiased assessing of the performance of chemoproteomic probes. Data were produced from the IPM-based QTRP (quantitative thiol reactivity profiling) experiments where light and heavy IPM-tagged samples mixed in different ratios (L/H = 1:10, 1:5, 1:2, 1:1, 2:1, 5:1 and 10:1). IPM is a clickable thiol reactive reagent with the iodoacetamide warhead.