HPLC vs LC-MS
HPLC and LC-MS answer different analytical questions. Buyers evaluating Chinese supplier COAs should understand what each technique measures before comparing purity numbers across vendors.
Complementary techniques
HPLC reports relative purity by chromatography. LC-MS supports identity by comparing observed mass with theoretical molecular weight. Many procurement programs use both on the same batch for new suppliers or high-risk sequences.
HPLC (purity by chromatography)
Relative abundance of the main peak versus other chromatographic peaks, reported as area percent.
Strengths
- Detects many related impurities and deletion sequences
- Common release test for catalog research peptides
- Quantifies main-component abundance when integration is valid
Limitations
- Does not confirm sequence identity by itself
- Co-eluting impurities may be invisible
- Results are not comparable across different methods or columns
- Does not assess sterility, endotoxin, or folding for complex peptides
LC-MS (identity by mass)
Observed molecular ion mass compared with theoretical molecular weight, including common adducts.
Strengths
- Confirms molecular weight consistent with expected sequence
- Useful for modified, long, or isomer-prone peptides
- Supports dispute resolution when HPLC purity alone is insufficient
Limitations
- Does not quantify all impurities without additional chromatography
- Adduct selection and deconvolution must be documented
- Does not replace method validation or scope review
Educational decision matrix
This table summarizes common buyer expectations. Your internal quality system may require more stringent packages.
| Scenario | Typical minimum package |
|---|---|
| Qualified supplier, routine catalog peptide | Batch HPLC with documented method; LC-MS when your QMS requires identity proof |
| New supplier qualification | HPLC plus LC-MS on the same batch; retain sample for dispute resolution |
| Modified or long peptide (for example GLP-1 class) | LC-MS identity with explicit adduct documentation; method transparency |
| Result dispute or failed internal assay | Independent third-party retest with agreed methods |
For laboratory research and analytical use only. Not for human consumption. Not intended to diagnose, treat, cure, or prevent any disease.