Peptide testing methods explained: HPLC-UV vs LC-MS

What is HPLC-UV peptide purity testing?

High-performance liquid chromatography with UV detection (HPLC-UV) separates a peptide from its impurities on a reversed-phase column and quantifies each peak by UV absorbance, typically at 214 nm where the peptide amide bond absorbs strongly. The main peak area, divided by the total integrated area, gives the reported percent purity. Common impurities detected include truncated sequences, deletion products, oxidation and side-chain modifications.

What is LC-MS peptide identity testing?

Liquid chromatography–mass spectrometry (LC-MS) measures the mass of the molecules eluting from the column. For a peptide, the observed monoisotopic mass is compared to the theoretical mass calculated from the sequence. A match within instrument tolerance confirms molecular identity. LC-MS does not, by itself, tell you how pure the sample is — that's what HPLC-UV does.

HPLC-UV vs LC-MS: what's the difference?

HPLC-UV answers "how much of this sample is the intended peptide?" LC-MS answers "is this actually the intended peptide?" Purity without identity can be misleading (a very pure sample of the wrong molecule is still wrong). Identity without purity is incomplete (the right peptide contaminated with 30% impurities is not what a customer expects). Florida Chemical reports both on every peptide COA.

When do you need peptide content/assay?

Content or assay quantifies how much peptide is actually in the vial by mass — separate from purity. It matters whenever a labeled concentration or dose is claimed, because a 95%-pure peptide can still contain significantly less active material than the label suggests once counterions, water and residuals are accounted for.

Extended peptide testing beyond identity and purity

Depending on intended use, additional tests may be appropriate: heavy metals by ICP-MS or ICP-OES, residual solvents by headspace GC-FID or GC-MS, microbial contamination and sterility, endotoxins by LAL or recombinant-factor assay, Karl Fischer moisture, particulate matter, and protein structure or aggregation. See the full menu on our services page.

Pricing and turnaround

Peptide purity testing by HPLC-UV is a flat $199.00 per sample. Standard turnaround is 24–48 hours from sample receipt at our Jacksonville, FL laboratory. Additional services — LC-MS identity, content/assay, heavy metals and residual solvents — are quoted separately.