Amoxicillin trihydrate Impuirty: (2S,5R,6R)-6-((R)-2-(4-hydroxyphenyl)-2-pivalamidoacetamido)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid (N-Pivaloyal Amoxicillin Impurity).