Pierce β-Glucan-Blocker is added to samples suspected of β-1,3-glucans contamination, preventing the occurrence of false positive results in endotoxin detection (LAL) assays. β-1,3-glucans contamination may arise from the presence of yeast and cellulosic materials. β-1,3-glucans, in sufficient amounts, can trigger a LAL response not emanating from an endotoxin-mediated response. This blocker contains <0.005 EU/mL endotoxin.