Understand the source comparison
Verify Glow Stack Purity: Testing Methods Comparison
HPLC (High-Performance Liquid Chromatography) Purity percentage, deletion sequences, aggregates 0.1% relative area $150–$300 Standard verification for all peptides; primary purity metric Required baseline. Without HPLC data, purity claims are unverifiable Mass
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This page preserves a source comparison for education. It does not add a rating, recommendation or clinical judgment.
- HPLC (High-Performance Liquid Chromatography)
- Purity percentage, deletion sequences, aggregates
- 0.1% relative area
- $150–$300
- Standard verification for all peptides; primary purity metric
- Required baseline. Without HPLC data, purity claims are unverifiable
- Mass Spectrometry (ESI-MS or MALDI-TOF)
- Molecular weight, sequence confirmation, adducts
- ±0.5 daltons
- $100–$250
- Identity verification; detects oxidation, misfolds
- Essential for sequence-critical peptides; HPLC alone can't confirm identity
- Amino Acid Analysis (AAA)
- Amino acid composition ratios
- ±2% per residue
- $200–$400
- Confirms sequence accuracy; used when MS is ambiguous
- Rarely needed if HPLC and MS are conclusive; most valuable for novel sequences
- Endotoxin Testing (LAL Assay)
- Bacterial lipopolysaccharide contamination
- 0.01 EU/mL
- $50–$150
- All in vivo work; cell culture with immune-sensitive lines
- Non-negotiable for animal studies; often skipped by budget suppliers
- Karl Fischer Titration
- Residual water content
- 0.01%
- $75–$150
- Accurate peptide content calculation
- Explains why 98% pure peptide weighs less than expected. Water isn't peptide