Technical Reference
Analytical Methodology
All testing is performed by independent accredited contract research organizations. This document describes the analytical methods, reporting standards, and flag criteria applied to published results.
Identity Confirmation
Identity testing establishes whether the compound present in the sample is consistent with the declared compound. Results are reported as confirmed, not confirmed, or inconclusive.
Liquid Chromatography -- Mass Spectrometry
The primary identity method. Molecular mass is measured by ESI-MS and compared to the theoretical mass of the declared compound within a tolerance of ±0.02 Da. Chromatographic retention time is compared to reference standards where available.
Nuclear Magnetic Resonance
1H-NMR is used for structural confirmation and as a secondary identity method. NMR provides structural information that complements mass-based identity confirmation. Requested as an add-on for novel or structurally complex compounds.
High-Performance Liquid Chromatography with UV Detection
Used for identity confirmation when a certified reference standard is available. The sample chromatographic peak is compared to the reference standard retention time and UV spectrum.
Purity Quantification
Purity is reported as a percentage of the compound of interest relative to all UV-absorbing species present at the detection wavelength. This is an analytical purity value, not a pharmaceutical-grade specification.
HPLC-UV Area Normalization
Purity is calculated as the area percentage of the target compound peak relative to all integrated peaks in the chromatogram. Detection wavelength is selected based on compound class (typically 214 nm or 220 nm for peptide bonds). Results are reported as a percentage to one decimal place.
Response Factor Consideration
Area normalization assumes equivalent UV response factors for all species. Where certified reference standards are available, external standard quantification is used instead.
Sterility and Endotoxin
These tests are available as optional add-ons for samples where the vendor makes sterility or endotoxin claims.
Sterility Testing
Membrane filtration method per USP <71> or equivalent pharmacopeial standard. Tests for the absence of aerobic bacteria, anaerobic bacteria, and fungi. Incubation period of 14 days.
Endotoxin Testing
Limulus Amebocyte Lysate (LAL) kinetic turbidimetric method per USP <85> or equivalent. Results reported as EU/mg. Positive results trigger an impurity_concern flag in the published record.
Flag Criteria
Flags are applied to published records based on objective analytical criteria. Flags describe analytical observations and do not constitute safety determinations or quality grades.
| Flag | Condition |
|---|---|
| Label Claim Variance | Measured purity differs from labeled purity by more than 5 percentage points |
| Identity Mismatch | Analytical data does not support the declared compound identity |
| Impurity Concern | Impurities above reporting threshold detected, or endotoxin positive |
| Incomplete Data | Testing was requested but results were not obtainable for a required method |
| Endotoxin Detected | Endotoxin detected above the test specification limit |
| Sterility Failed | Microbial growth observed during sterility incubation period |
Laboratory Qualifications
All contract laboratories used by PeptideVerify hold ISO/IEC 17025 accreditation or equivalent for the test methods performed. Laboratory selection criteria include independence from vendors and submitters, demonstrated proficiency in relevant analytical methods, capacity for chain-of-custody documentation, and willingness to provide raw instrument data for audit purposes. A current list of partner laboratories is available upon request.