What does “≥99% purity” mean?

“≥99% purity” means that, in laboratory analytical testing, the primary compound of interest makes up at least 99% of the measured sample, and the remaining portion consists of trace-level impurities (typically minor byproducts from synthesis, residual reagents, salts/counter-ions, moisture, or other small related compounds). The exact method and reporting details are shown on the product’s Certificate of Analysis (COA), which is the most specific, lot-level documentation.

In research chemical manufacturing, 99%+ is generally a high benchmark because it indicates the sample is overwhelmingly composed of the intended compound, with only small amounts of other detectable material. Lower purities can imply a higher proportion of secondary peaks/unknowns on analytical testing, which may introduce more variability in lab results.