Ziffer

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How to read a specification, a purity figure and a certificate — and how to check each one without taking a seller’s word for it.

  • 4 min read

    What an HPLC purity figure measures

    A purity percentage is a ratio of peak areas from one chromatographic run. What the figure covers, what it leaves out, and what to read beside it.

  • 4 min read

    Four figures that identify a peptide

    CAS number, sequence, molecular formula and molecular mass. What each one states, how the four check one another, and where to verify them yourself.

  • 3 min read

    Five things a certificate has to state

    A certificate of analysis is evidence only when it names its laboratory, batch, method, date and result. Why each field matters, and how to check one.