CATO Reference Standards — technical guides https://www.cato-standard.com/guides/ 2026-10-07T08:00:00+00:00 How to Choose a Reference Standard Supplier https://www.cato-standard.com/guides/choosing-a-reference-standard-supplier/ 2026-10-05T08:00:00+00:00 A practical checklist for evaluating reference standard suppliers on documentation, traceability, lot consistency, logistics, and technical support. How to Read a Certificate of Analysis (COA) https://www.cato-standard.com/guides/how-to-read-a-certificate-of-analysis/ 2026-10-05T08:00:00+00:00 A field-by-field guide to reading a certificate of analysis for reference standards, covering identity, purity, content basis, and what to query. Stable Isotope-Labelled Standards and When to Use Them https://www.cato-standard.com/guides/isotope-labelled-standards-guide/ 2026-10-05T08:00:00+00:00 When stable isotope-labelled standards earn their place in an analytical method, what to specify when ordering, and the traps in LC-MS and GC-MS work. What Analytical Labs Need to Know About Nitrosamines https://www.cato-standard.com/guides/nitrosamine-impurities-guide/ 2026-10-05T08:00:00+00:00 Where nitrosamine impurities come from, how laboratories detect and quantify them, and the documentation regulators now expect to see. What Is an Impurity Reference Standard? A Lab Guide https://www.cato-standard.com/guides/what-is-an-impurity-reference-standard/ 2026-10-05T08:00:00+00:00 Learn what an impurity reference standard is, how it is characterised, how it differs from a working standard, and how to use one correctly.