Lab Testing & Purity
IGF-1 LR3 Lab Testing & Purity Standards: HPLC, MS & Endotoxin
3 min read•Published 2025-11-05•Quality Peptide USA Research
IGF-1 LR3 (Long Arginine 3 IGF-1) is a recombinant 83-amino-acid analog of human insulin-like growth factor 1. An N-terminal extension and an arginine substitution at position 3 reduce binding to IGF-binding proteins, extending the molecule's research half-life relative to native IGF-1.. This guide covers lab testing & purity for IGF-1 LR3 — written for laboratory researchers sourcing US-synthesized peptides from Quality Peptide USA.
Purity by Reverse-Phase HPLC
Every batch of IGF-1 LR3 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 IGF-1 LR3 product page.
Identity by Mass Spectrometry
IGF-1 LR3 identity is confirmed by electrospray ionization (ESI) or MALDI-TOF mass spectrometry. The observed molecular ion is compared against the calculated mass (≈ 9117.5 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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