Question 1

What is a Certificate of Analysis (COA)?

Accepted Answer

A Certificate of Analysis is the analytical-chemistry record of a research-compound batch. At Nexus Laboratory each COA documents HPLC area-percent purity (target ≥98%), mass spectrometry identity confirmation (expected versus observed molecular mass), endotoxin screening results, batch number, manufacturing date, expiry date, and the testing laboratory. Every COA is publicly accessible from the product page — no login required. See the public COA archive at /lab-verified.

Question 2

How does Nexus verify peptide purity?

Accepted Answer

Every research-compound batch is tested by independent third-party laboratories — not in-house. Reverse-phase HPLC measures area-percent purity against a release threshold of ≥98%, mass spectrometry confirms compound identity by comparing observed molecular mass with the expected value, and endotoxin screening checks for contamination introduced during synthesis or handling. Results are published on a branded Nexus Certificate of Analysis with a public verification URL.

Question 3

What is HPLC purity testing?

Accepted Answer

High-Performance Liquid Chromatography (HPLC) is the standard analytical method for measuring research-peptide purity. A small sample of the compound is separated through a chromatography column under controlled conditions; the resulting chromatogram shows the area-percent purity (the proportion of the main compound versus impurities) and retention time. Nexus publishes the HPLC value and method on every batch certificate of analysis.

Question 4

What is mass spectrometry identity confirmation?

Accepted Answer

Mass spectrometry confirms that the compound in a vial actually matches the compound on the label by measuring its molecular mass. The expected molecular mass (calculated from the sequence or structure) is compared to the observed mass; matching values within a ppm tolerance confirms identity. Nexus publishes both expected and observed mass on every batch certificate.

Question 5

What does "in-vitro research use only" mean?

Accepted Answer

In-vitro research use means the compound is sold for laboratory experiments conducted outside a living organism — typically in test tubes, well plates, or cell cultures. Compounds labeled in-vitro research use only are not intended for human consumption, veterinary use, or any clinical or therapeutic application. Customers are responsible for ensuring their research complies with applicable institutional, local, state, and federal regulations.

Question 6

How are research peptides stored and handled?

Accepted Answer

Research peptides are typically supplied as a lyophilized powder. Storage recommendations vary by compound: most are stored at -20°C for long-term stability and refrigerated after reconstitution. Reconstitution requires a research-grade solvent (bacteriostatic water, acetic-acid water, or sterile water depending on the compound). Specific handling and storage guidance is documented on each Nexus product page.

Question 7

How do I place an order?

Accepted Answer

Add compounds to your cart and proceed to checkout. Cold-chain shipping is included on all orders.

Question 8

Do you ship outside the United States?

Accepted Answer

No. Nexus Laboratory ships exclusively within the United States. We do not accept international orders.

Question 9

When will my order ship?

Accepted Answer

Orders placed before 2pm ET ship the same business day, cold-chain.

Question 10

Where can I see the COA for a batch?

Accepted Answer

Every product page links to the most recent batch COA. The full archive is on the Lab Verified page at /lab-verified.

Question 11

What does "lab verified" mean here?

Accepted Answer

Every batch is third-party HPLC + mass spectrometry + endotoxin tested by independent laboratories. The COA is published before listing.

Question 12

Are these for human use?

Accepted Answer

No. All compounds sold by Nexus Laboratory are supplied for in-vitro research use only. Not for human consumption, veterinary use, or any clinical or therapeutic application.

Question 13

What is the difference between research-use-only and pharmaceutical-grade?

Accepted Answer

Research-use-only compounds are supplied for in-vitro laboratory research and are not intended for human consumption or therapeutic use. Pharmaceutical-grade material refers to compounds manufactured under cGMP (current Good Manufacturing Practice) conditions and validated through clinical-trial pathways for human administration. The two categories differ in manufacturing controls, documentation requirements, regulatory status, and end use. A research-grade compound can have ≥99% HPLC purity and pass identity and endotoxin testing without ever being intended for or appropriate for human use. Nexus supplies research-use-only material exclusively.

Question 14

How are research peptides priced compared to clinical-grade?

Accepted Answer

Research-grade peptides are typically priced an order of magnitude or two below clinical/pharmaceutical-grade material because they do not carry the cGMP manufacturing, full traceability, and regulatory validation overhead required for human-administration material. Nexus prices reflect research-grade scope: the analytical chemistry is documented (HPLC purity, mass spec identity, endotoxin), but cGMP-validation steps such as facility certification audits and regulatory pathway documentation are not included. Pricing per variant is shown on each product page.

Question 15

What does ≥99% purity actually mean in HPLC terms?

Accepted Answer

A reported HPLC purity of ≥99% means that, in the chromatogram, 99% of the area under all UV-active peaks corresponds to the main compound peak. The remaining 1% can include synthesis-related impurities, related peptide species, oxidized variants, deletion sequences, or counterion. This is a measurement of relative chromatographic abundance, not absolute mass-percent of the bulk material — water content, residual solvents, and non-UV-active material are not captured in HPLC area-percent. Nexus publishes both the HPLC method and the area-percent value on every Certificate of Analysis.

Question 16

How are blends (e.g., BPC-157 + TB-500) analyzed for purity?

Accepted Answer

Blend products combine two or more peptides in a single vial. HPLC area-percent purity is reported for each component peak separately; the mass spectrometry identity check confirms each component's mass against its expected value. A typical blend COA documents the purity and observed mass for each peptide. Some research questions are more cleanly addressed using standalone components rather than blends — researchers commonly compare standalone BPC-157 and TB-500 against the BPC+TB blend before choosing a format.

Question 17

How long do lyophilized peptides remain stable?

Accepted Answer

Lyophilized (freeze-dried) peptides stored at -20°C in their original sealed vial have multi-year stability for most research peptides — typically 2-4 years from manufacturing date for the catalog's standard compounds. Stability depends on the compound: sequences with susceptible residues (e.g., methionine to oxidation, glutamine to deamidation) may have shorter practical shelf lives. After reconstitution, stability drops to weeks at refrigerated temperatures and to days for some compounds. Each product page documents compound-specific storage and handling.

Question 18

What is the difference between acetate and trifluoroacetate (TFA) salt forms?

Accepted Answer

Synthetic peptides are typically isolated as either acetate or trifluoroacetate salts depending on the purification method. TFA is residual from reverse-phase HPLC purification with TFA-containing mobile phases; acetate is the result of salt exchange to remove TFA. For most research applications, the salt form is unlikely to affect the experimental result. For quantitative research where the counterion contributes to mass-per-vial calculation, the salt form matters — TFA is heavier than acetate, so a given mass of TFA-salt peptide contains slightly less actual peptide than the same mass of acetate-salt. Nexus documents the salt form per compound.

Question 19

What is a research bioregulator — how does it differ from a peptide hormone?

Accepted Answer

A peptide bioregulator is a short peptide (typically 2-7 amino acids) that participates in tissue-specific regulatory signaling in research models. The category overlaps with peptide hormones — short peptides can act on hormone receptors — but the Khavinson research lineage uses bioregulator to describe peptides whose research-context activity is described as tissue-regulatory or peptide-bioregulator-class rather than acting on a single named hormone receptor. The Khavinson 4-amino-acid bioregulators (e.g., bronchogen, cardiogen, epithalon) are the canonical research representatives of this class. Catalog: /shop/category/russian-bioregulators.

Question 20

Why do Russian bioregulators (Khavinson peptides) have unusual research history?

Accepted Answer

V.Kh. Khavinson and colleagues at the St. Petersburg Institute of Bioregulation and Gerontology described a family of short tetrapeptide bioregulators starting in the 1970s. The research history is documented largely in Russian biochemistry literature with a different publication-style convention than Western peptide research, which is partly why the Khavinson peptide family is less familiar to Western research audiences than its scope warrants. The 15 Khavinson-family compounds in the Nexus catalog cover the documented organ/tissue-axis research applications. The history is summarized in the peptide research database.

Question 21

What does "fusion protein" mean for compounds like ACE-031?

Accepted Answer

ACE-031 is a fusion protein — specifically, an activin type IIB receptor (ActRIIB) extracellular domain fused to an IgG-Fc immunoglobulin region. The fusion architecture serves two research purposes: the receptor domain provides the binding specificity (activin/myostatin family ligands) and the Fc fusion provides longer in-vitro stability. Fusion proteins differ from simple peptides in their molecular weight, structure, and quality-control requirements — larger proteins require SDS-PAGE and Western blot analysis in addition to mass spectrometry for full characterization.

Question 22

How are CJC-1295 With DAC and Without DAC different?

Accepted Answer

Both compounds are synthetic GHRH analogs. CJC-1295 Without DAC (also marketed as Modified GRF 1-29) is a short-acting research analog with a half-life similar to native GHRH. CJC-1295 With DAC includes a Drug Affinity Complex (DAC) — a maleimidopropionic acid linker enabling covalent binding to serum albumin, dramatically extending the research half-life. The two compounds answer different research questions: short-acting GHRH research uses the no-DAC variant; sustained-signaling research uses the DAC variant. Both compounds appear in the GHRH analogs mechanism family.

Question 23

What information is included in a Nexus Certificate of Analysis?

Accepted Answer

Every Nexus Certificate of Analysis documents: compound name and Nexus batch ID, manufacturing and expiry dates, net peptide weight per vial, reverse-phase HPLC area-percent purity (with method, column, and retention time), mass spectrometry expected vs observed molecular mass (with method and ppm error), endotoxin testing result and method (LAL gel-clot), physical appearance, storage requirements, the testing laboratory name, and the analyst signature with certified-by date. The full per-field walkthrough is documented on the Lab Verified page.

Question 24

What are common research applications for GLP-1 receptor agonists in laboratory studies?

Accepted Answer

GLP-1 receptor agonists are studied in preclinical research models for receptor pharmacology (binding affinity, signaling cascade research), pancreatic beta-cell research, satiety pathway research in animal models, and multi-pathway research using dual (GIP/GLP-1) or triple (GLP-1/GIP/glucagon) agonists. Common comparator research uses semaglutide and tirzepatide side-by-side; multi-agonist research uses retatrutide, mazdutide, and survodutide. All Nexus GLP-1 compounds are supplied for in-vitro research only and no therapeutic or dosing guidance is provided.

Question 25

How do I verify a Nexus batch ID is legitimate?

Accepted Answer

Every Nexus batch ID follows the format NEX--- and resolves through a dedicated verification URL: /verify/. The verification page shows the batch's manufacturing date, expiry date, HPLC purity, mass spectrometry result, and a link to the full branded Certificate of Analysis. If a batch ID does not resolve through that route, or if the data shown does not match the printed COA, the batch should be treated as unverified — contact research support at support@nexuslaboratory.org.

Question 26

What is the difference between semaglutide, tirzepatide, retatrutide, and survodutide?

Accepted Answer

All four are incretin-pathway peptides but with different receptor pharmacology. Semaglutide is a single GLP-1 receptor agonist (the simplest and longest-studied of the four). Tirzepatide is a dual GIP/GLP-1 agonist. Retatrutide is a triple-agonist research compound active at GLP-1, GIP, and glucagon receptors. Survodutide is a dual GLP-1/glucagon agonist. The four are commonly studied as a comparator series in receptor-pharmacology research models examining how added receptor targets change the signaling profile. All are supplied for in-vitro research only.

Question 27

How does Nexus ensure compound stability during USA shipping?

Accepted Answer

Nexus ships via USPS within the United States. Lyophilized peptides are stable at ambient temperatures for the duration of typical USPS transit (1-5 business days), and short-term ambient exposure is generally well-tolerated by the catalog's standard compounds in their sealed vials. Shipments are packaged to limit temperature spikes and physical disturbance. Upon receipt, compounds should be transferred to long-term storage conditions (typically -20°C). Specific handling guidance is documented on each product page; questions can be sent to support@nexuslaboratory.org.

Common questions.

Common questions.

Related resources

Related resources