What Are the Best China Generic Peptide API Suppliers?

Evaluation Dimension	Recommended Acceptance Point	Anonymous Supplier A	Anonymous Supplier B	Anonymous Supplier C	How to Verify
Product identity	Identity confirmed by at least two orthogonal techniques, such as LC-MS and analytical HPLC.	LC-MS and HPLC reported	HPLC reported; LC-MS not supplied	LC-MS, HPLC, and peptide mapping reported	Review the original test report, method number, chromatograms, and instrument date.
Analytical HPLC purity	Common research-grade screening target: not less than 98.0%, unless the product specification states otherwise.	98.7% to 99.3% across three reported batches	97.9% to 98.8% across three reported batches	99.1% to 99.6% across three reported batches	Confirm column type, mobile phase, detection wavelength, integration rules, and whether purity is area percentage.
HPLC batch consistency	Small batch-to-batch variation is preferred; a practical screening rule is a range of no more than 1.0 percentage point.	0.6 percentage-point range	0.9 percentage-point range	0.5 percentage-point range	Request chromatograms and complete batch results instead of relying only on a single representative COA.
Crude peptide purity	Higher crude purity can reduce downstream purification burden, but it should not replace final API testing.	78% to 84%	72% to 80%	82% to 87%	Compare crude HPLC traces, impurity profiles, and the purification process used for the same sequence.
Overall isolated yield	Evaluate yield together with purity, sequence length, protection strategy, and peptide difficulty; no universal pass value applies.	31% to 38%	26% to 35%	34% to 41%	Ask for the calculation basis, starting resin loading, actual isolated mass, and number of manufacturing batches.
Batch record availability	At least three recent, product-specific batches should be available for technical review.	Three batch COAs and summary records available	One COA available; additional batch records pending	Three batch COAs plus deviation summary available	Check batch numbers, manufacturing dates, release dates, retest dates, and document revision control.
Residual solvents	Results should be reported against the applicable ICH Q3C category and product-specific limits.	Reported with specification limits	Not reported on the supplied COA	Reported with specification limits	Request a solvent panel, analytical method, reporting limit, and actual result for each relevant solvent.
Water content	Method and limit should be defined for the specific peptide and salt or counter-ion form.	Karl Fischer result reported	Loss-on-drying result reported	Karl Fischer result reported	Do not directly compare Karl Fischer and loss-on-drying results without considering method differences.
Counter-ion and salt form	The stated form must match the ordered material and the amount used in assay calculations.	TFA salt clearly identified	Salt form stated but assay basis unclear	Acetate salt and assay basis identified	Verify molecular weight, counter-ion content, assay correction, and conversion factors.
Endotoxin testing	Required when the intended use is sensitive to endotoxin; limit must be agreed before ordering.	Testing available on request	Not included in standard release package	Result included for the tested lot	Confirm sample preparation, dilution, assay sensitivity, result units, and product-specific acceptance criteria.
Stability and retest data	Real-time or accelerated stability data should support the proposed retest period and storage condition.	Accelerated data available	No product-specific stability data supplied	Real-time and accelerated data available	Review storage temperature, packaging configuration, sampling intervals, and degradation markers.
Quality-system evidence	Documented quality procedures, controlled specifications, deviation handling, and change control are preferred.	Quality-system questionnaire completed	Basic quality documents supplied	Quality-system questionnaire and audit package supplied	Request audit responses, change-control policy, OOS procedure, and data-integrity statement.
Overall screening result	Prioritize transparent, reproducible batch evidence over a single high purity number.	Strong technical candidate	Requires additional documentation	Strong technical candidate	Use a risk-based qualification process and confirm all critical attributes with current product-specific records.
Data-use note: The supplier labels and values above are anonymized benchmark-style records for comparison layout purposes. They are not claims about any named company or commercial product. Before qualification, verify every value against original, product-specific COAs, chromatograms, batch records, validated analytical methods, and applicable specifications.