QLD Analytical blog https://qldanalytical.com/blog/ Independent testing guides for research samples. en-au What a certificate of analysis (COA) should show — and red flags to look for https://qldanalytical.com/blog/what-a-coa-should-show/ https://qldanalytical.com/blog/what-a-coa-should-show/ Sat, 17 Oct 2026 09:00:00 +1000 A useful COA ties results to a specific lot, names the methods, and lets you verify who tested the sample. HPLC purity vs net peptide content: why the two numbers differ https://qldanalytical.com/blog/purity-vs-net-peptide-content/ https://qldanalytical.com/blog/purity-vs-net-peptide-content/ Sat, 17 Oct 2026 09:00:00 +1000 High HPLC purity does not mean the vial is 100% peptide by weight — salts, counterions and moisture also affect the numbers.