A Branched Chain Amino Acid (BCAA) contains a branch structure side chain with one central carbon connected to at least three other carbon atoms. The three BCAAs coded by the human genome are leucine, valine, and isoleucine. BCAAs play key roles in animal metabolism and physiology; they enhance protein synthesis, signaling pathways, and glucose metabolism. Cell Biolabs’ Branched Chain Amino Acid Assay Kit is a simple colorimetric assay that measures the total amount of free BCAAs present in foods or biological samples in a 96-well microtiter plate format. BCAAs in polypeptide chains (peptides and proteins) are not detected. Sample BCAA concentrations are determined by comparison with a known L-Leucine standard. The kit has a detection sensitivity limit of 15.6 uM. Each kit provides sufficient reagents to perform up to 192 assays, including blanks, L-Leucine standards and unknown samples. Note each sample replicate requires 2 wells: one positive well and one endogenous control well.