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Lab Testing & Purity

TB-500 Lab Testing & Purity Standards: HPLC, MS & Endotoxin

3 min read•Published 2025-03-06•Quality Peptide USA Research

TB-500 is a synthetic version of the active 17-amino-acid region of thymosin beta-4 (Tβ4), a naturally occurring polypeptide present in nearly all human and animal cells. TB-500 is widely used in laboratory research focused on actin sequestration, cell migration, and tissue regeneration.. This guide covers lab testing & purity for TB-500 — written for laboratory researchers sourcing US-synthesized peptides from Quality Peptide USA.

Purity by Reverse-Phase HPLC

Every batch of TB-500 is analyzed by reverse-phase HPLC using a C18 stationary phase and a water/acetonitrile gradient with 0.1% TFA. The release specification is ≥ 99% purity by area-under-curve at 220 nm. The chromatogram is included in the full certificate of analysis PDF available on the TB-500 product page.

Identity by Mass Spectrometry

TB-500 identity is confirmed by electrospray ionization (ESI) or MALDI-TOF mass spectrometry. The observed molecular ion is compared against the calculated mass (≈ 4963 g/mol) and must match within 1 Da to pass release. Sequence-level confirmation is performed on representative lots through MS/MS fragmentation.

Endotoxin and Bioburden

Every batch is screened with the Limulus Amebocyte Lysate (LAL) assay. Release specification: < 0.10 EU/mg. Bioburden is verified by membrane filtration with target < 1 CFU per vial. These thresholds matter for cell-culture work where endotoxin contamination confounds inflammatory and proliferation readouts.

Water Content and Residual Solvents

Karl Fischer titration verifies water content below 5%, ensuring the lyophilized cake is fully dry. Residual organic solvent screening (gas chromatography) confirms acetonitrile and TFA residuals are within USP <467> Class 3 limits. This is one of the most overlooked QC steps when sourcing peptides from overseas suppliers — but it directly influences downstream cell viability.

Research Use Only

All content is for laboratory and in-vitro research contexts only. Not intended to diagnose, treat, or prevent any condition. Not for human or veterinary consumption.

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