When purchasing acids (such as Sulfuric, Hydrochloric, or Citric acid), the most critical factor is Concentration/Purity levels. You must verify the assay percentage (e.g., 98% for industrial sulfuric acid) and the grade classification (e.g., Technical Grade, Food Grade, or Pharmaceutical Grade). Additionally, check for impurity profiles, specifically the presence of heavy metals like Arsenic or Lead, which must fall below industry-standard thresholds to ensure chemical stability and process safety.