TB-500 vs Thymosin Beta-4: China Supplier Guide

Do not use TB-500 as the complete identity

Write the buyer-approved amino-acid sequence, residue count, N- and C-terminal states, modifications, counterion where applicable, expected molecular formula and mass, physical form, nominal quantity and Research Use Only scope. State whether the request is for the N-acetylated seven-residue construct commonly written Ac-LKKTETQ, the complete Thymosin Beta-4 sequence, or another explicitly defined material. TB-500, TB4, Thymosin B4 and Fragment 17-23 should remain separate aliases until documents prove exactly what each supplier means. A product photo or shared catalog category cannot resolve the construct.

Distinguish the seven-residue fragment from full-length TB4

The short N-acetylated construct and full-length 43-residue Thymosin Beta-4 differ in sequence length and expected molecular mass by several-fold. They are not interchangeable simply because a supplier uses TB-500 in both titles. Compare every residue, order, terminal group, modification and expected mass against the purchase specification. Also separate Ac-LKKTETQ from an unacetylated LKKTETQ sequence and from other thymosin-derived fragments such as Ac-SDKP. A different terminal group or residue boundary is a different controlled identity and requires a new SKU, technical assessment and explicit buyer approval.

Use molecular mass as an early identity screen

Require complete mass-spectrometric evidence linked to the offered batch and compare the observed ion pattern or deconvoluted mass with the expected construct. A result near the target for a seven-residue peptide cannot qualify a 43-residue product, and the reverse is equally invalid. An approximately 42 Da difference may indicate a missing acetyl group and should not be dismissed as normal variation without a justified interpretation. Mass evidence supports molecular identity but does not alone prove residue order, purity, quantity or every structural feature. Review the raw or complete report, sample identifier, method, dates and authorization rather than only a cropped pass statement.

Control 2mg, 5mg and 10mg as separate finished formats

Create one RFQ row per strength with the exact sequence, amount per unit, vial count, total target material, fill tolerance, packaging, parent lot, finished lot and price basis. A 10mg vial is not documented by multiplying a 2mg label because filling records, containers, formulations and finished-lot genealogy may differ. Ask which quantitative method or controlled filling record supports each nominal amount and whether the figure means net target peptide or total lyophilized mass including water, counterions or excipients. Keep sequence identity, chromatographic purity and quantitative content as separate acceptance fields.

Make the COA, label and custody chain use one construct

The signed batch COA should state the complete controlled identity, sequence or an unambiguous specification reference, lot, identity result, HPLC purity, quantitative-content result or basis, applicable release attributes, methods, dates and authorization. Require the specification, analytical reports, label, invoice and packing list to carry the same product code and strength. Map the legal seller, synthesis site, laboratory, filler, release authority, stock owner and shipper. Quarantine any conflict involving TB-500 versus TB4, fragment length, acetylation, molecular mass, strength or lot until a traceable supplier investigation and corrected documents are approved.

Build one comparable wholesale RFQ matrix

Send every candidate the same fields: controlled identity, strength, vial count, total material, target purity or composition, identity method, quantitative-content basis, offered lot, testing status, packaging, documents, MOQ, lead time and shipping term. Mark missing answers as exceptions instead of filling gaps with assumptions. Separate testing, setup, customization and transport costs from recurring unit price. A standardized matrix gives scientific, purchasing and quality reviewers one auditable record and prevents an incomplete offer from appearing cheaper simply because it describes less work.

Apply a batch-focused quality-control review

Define every required attribute, acceptance criterion, method and record before purchase. Use the quality-control framework to connect each supplier claim to evidence and its method scope. Check sample identifiers, dates, report numbers, units and lot relationships across the complete reports. Batch-specific evidence is more decision-useful than a representative certificate. Preserve original files, record revisions and investigate contradictions before approving shipment. Where risk warrants, arrange independent testing under a documented sampling and custody plan.

Create a documentation gate before dispatch

List the required batch COA, analytical attachments, SDS, specification, supported storage statement, label proof, invoice and packing list in the RFQ and purchase order. Reconcile product, strength, lot, quantity and revision across records with the documentation guide. Require replacement documents when the offered lot changes. The importer remains responsible for current destination requirements. Research-use wording improves clarity but cannot guarantee customs entry or replace destination-specific legal and broker review.

Verify supplier and batch ownership

Document the legal seller, manufacturing site, analytical laboratory, filling or packaging site, inventory owner, release authority and dispatch entity for the exact SKU. A trading or coordination company can work with qualified partners, but roles and accountability must be transparent. Ask who owns the batch record, authorizes release, handles deviations and provides corrective action. Require advance notification when a critical party changes. Business-registration evidence supports identity but does not replace technical qualification of the offered lot.

Plan logistics and receiving controls

Confirm dispatch location, carrier, shipping term, packaging configuration and realistic production, release and transit windows. Reject guarantees of customs clearance or misleading declarations. On receipt, document package condition, seals, product, strength, lot and quantity, then connect internal inventory to the supplier batch. Store according to the applicable approved specification and quarantine unexplained damage, label conflicts, quantity differences or excursions until a documented quality decision is completed.

Use actual performance for repeat-order approval

A controlled evaluation order should use the same specification and evidence expectations planned for wholesale scale. Assess document accuracy, packaging, delivery time, communication and corrective response. Update a supplier scorecard from observed performance rather than catalog breadth or claims. For every new lot, repeat the batch review and approve current documents before dispatch. Require notification before changes to material specification, manufacturing, testing, filling, labels, packaging or other buyer-approved conditions.

Related products and same-category guides

• TB-500 2mg
• TB-500 5mg
• TB-500 10mg
• Fragment 17-23 10mg
• BPC-157 vs TB-500 Research Differences
• Fragment 17-23 Sequence and COA Guide

Frequently asked questions