Third-Party Testing

Every batch of Nexus Compounding peptides is submitted to an independent, accredited laboratory before a single vial is assigned a lot number or made available for purchase. No product ships under a lot without a complete panel of passing test results on file.

Test-first, release second. Batch samples are pulled from production and sent to the third-party lab before any lot number is assigned. Results must return clean across every parameter before the batch enters inventory.

Independent Laboratory Testing

Nexus Compounding does not conduct its own release testing. All analytical work is performed by a third-party laboratory with no financial stake in the outcome of the results. This structural separation ensures objectivity and protects the integrity of every Certificate of Analysis (COA) we issue.

Samples are pulled from the production batch, not assembled separately for testing purposes.
COAs are issued directly by the third-party laboratory and are available for each lot via the QR code on the product label.
Testing is performed per applicable USP methodology for each parameter.

Endotoxin, Heavy Metal & Sterility Testing

These three categories represent the most critical safety parameters for research-grade compounds. Together they confirm the absence of biological contaminants, toxic elemental impurities, and viable microbial organisms in the finished product.

Endotoxin Testing

Endotoxins are lipopolysaccharide fragments shed from the outer membrane of gram-negative bacteria. Even in the absence of live organisms, endotoxin residue in a vial can trigger a severe pyrogenic (fever) response. Endotoxin testing is therefore mandatory regardless of sterility results.

Method: Limulus Amebocyte Lysate (LAL) assay per USP <85>.
Acceptance criterion: Results must fall below the established endotoxin limit for the product category.
Significance: A vial can pass sterility and still fail endotoxin — both tests are independently required for lot release.

Heavy Metal Testing

Elemental impurities including lead, arsenic, cadmium, and mercury can be introduced through raw API sourcing, reagents, or manufacturing equipment. Heavy metal contamination at trace levels poses serious toxicological risk and is screened on every batch.

Method: Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) per USP <232> / <233>.
Elements screened: Lead (Pb), Arsenic (As), Cadmium (Cd), Mercury (Hg), and other elemental impurities per the applicable ICH Q3D limits.
Sourcing control: API suppliers are selected in part on their elemental impurity documentation. Batch testing provides a final verification layer independent of supplier CoAs.

Sterility Testing

Sterility testing confirms the absence of viable aerobic bacteria, anaerobic bacteria, and fungi in the finished product. It is one of the most time-intensive tests in the panel — not because the analytical procedure is complex, but because biology cannot be rushed.

The incubation requirement and why it matters for turnaround time.

Per USP <71> (Sterility Tests), samples must be incubated for a minimum of 14 days under controlled conditions — 7 days at 20–25°C (aerobic and anaerobic organisms) and 7 days at 30–35°C (fungi and yeast). This dual-temperature incubation window exists because different classes of microorganism proliferate at different thermal ranges. Shortening the incubation period would create false negatives — a contaminated batch could appear sterile simply because the organisms had not yet grown to detectable levels.

This 14-day minimum is a hard regulatory floor, not a guideline. It cannot be accelerated.

What this means for lot release timing

Sterility testing alone accounts for a minimum of two weeks of the post-production timeline. Add transit time to the laboratory, laboratory intake and preparation, result reporting, and internal review — and the full sterility component of lot release realistically spans 3–4 weeks from sample submission to a reportable result.

Nexus Compounding does not release product during the incubation window. Every lot remains quarantined until all sterility, endotoxin, heavy metal, and purity results are received, reviewed, and confirmed passing. This delay is the cost of doing sterility testing correctly — and it is non-negotiable.

Method: Direct inoculation or membrane filtration per USP <71>.
Incubation period: 14 days minimum — no exceptions.
Media used: Fluid Thioglycollate Medium (FTM) for aerobic and anaerobic bacteria; Soybean-Casein Digest Medium (SCD) for aerobic organisms and fungi.
Failure criterion: Any evidence of turbidity, precipitation, or visible growth constitutes a failing result. The batch does not ship.

HPLC Purity Testing

High-Performance Liquid Chromatography (HPLC) is used to verify peptide identity and quantify purity. Nexus Compounding targets and reports purity of >99% by HPLC area normalization.

Method: Reverse-phase HPLC with UV detection.
What it confirms: That the peptide present in the vial matches the declared sequence, and that impurities (truncated sequences, oxidation products, related substances) are quantified and within acceptable limits.
Mass spec confirmation: LC-MS or MALDI-TOF is used where identity confirmation beyond retention time is required.

Net Peptide Content

HPLC purity and net peptide content (NPC) are related but distinct measurements. HPLC purity expresses how much of the detectable material is the target peptide relative to impurities. Net peptide content expresses what fraction of the total vial mass is actually peptide — accounting for counterions, residual moisture, and salts that contribute to gross weight but are not the active compound.

A vial can return 99% HPLC purity while containing only 75–85% net peptide content by weight. The remainder is not contamination — it is largely trifluoroacetate (TFA) counterions from synthesis, bound water, and residual salts. Without an NPC measurement, the actual peptide dose per vial is unknown.

Method: Amino Acid Analysis (AAA) per USP <1052> or quantitative UV absorption combined with moisture and counterion data.
What it confirms: The true mass of peptide per vial, independent of counterions or bound water. NPC is reported as a percentage of total vial mass.
Why it matters: NPC is the only measurement that allows accurate dosing by mass. Researchers relying on gross weight without NPC data are working with an unknown effective quantity.
Acceptance criterion: Net peptide content must meet the declared specification before a lot is released. Lots below specification threshold are rejected regardless of HPLC purity result.

Additional Parameters

The following parameters are also screened as part of the complete release panel:

Residual Moisture (Karl Fischer): Lyophilized peptides are tested to confirm water content is within specification. Excess moisture degrades lyophilized product over time and indicates an incomplete freeze-drying cycle.
Residual Solvents (GC-Headspace): Solvents used during synthesis or formulation — such as acetonitrile, methanol, or DMF — are screened against ICH Q3C limits to confirm they are not present above allowable thresholds.
Appearance: Visual inspection of cake morphology, color, and reconstitution behavior is documented for each lot.

Certificate of Analysis & Lot Traceability

Every Nexus Compounding vial carries a unique lot number and a QR code that links directly to the third-party COA for that specific batch. The COA includes the laboratory name, accreditation, test methods, results, and release date.

COAs are issued by the testing laboratory, not by Nexus Compounding.
Lot numbers are traceable from COA back through manufacturing records.
No lot is assigned a number or entered into inventory until all tests return passing results.

Questions

For questions about testing methodology, COA requests, or lot-specific documentation, contact: [email protected]