So you’ve decided to begin working with research peptides in your laboratory. Whether you’re setting up in-vitro assays, exploring receptor binding studies, or conducting stability experiments, your first peptide purchase can feel overwhelming. There are dozens of vendors, confusing purity numbers, unfamiliar equipment requirements, and very little guidance written for true beginners.

This guide walks you through everything you need to know before making your first purchase — from evaluating vendors and reading Certificates of Analysis to assembling your equipment and avoiding the mistakes that waste time and money.

What Are Research Peptides?

Before buying anything, let’s establish the basics. Peptides are short chains of amino acids — typically between 2 and 50 amino acids long — linked by peptide bonds. They’re smaller than proteins but share similar structural principles.

Research peptides are synthesized in laboratories using solid-phase peptide synthesis (SPPS) and are sold exclusively for in-vitro laboratory research, scientific study, and educational purposes. They are not intended for human consumption and are not approved medications. For a more thorough introduction, see our comprehensive guide to what research peptides are.

Common research peptides include BPC-157, various GLP-1 receptor agonist analogs, growth hormone-releasing peptides (GHRPs), and melanocortin receptor ligands. Each has a defined amino acid sequence, molecular weight, and set of physical properties that should be documented and verifiable.

How to Evaluate a Peptide Vendor

Not all peptide vendors are equal. The difference between a trustworthy supplier and a questionable one often comes down to transparency, testing, and professionalism. Here’s what to look for:

Third-Party Certificates of Analysis (COAs)

This is the single most important factor. A Certificate of Analysis is a document that details the identity, purity, and quality of a specific batch of peptide. Critically, you want third-party COAs — testing performed by an independent laboratory, not by the vendor themselves.

Why does this matter? A vendor testing their own product has an obvious conflict of interest. Third-party testing by a recognized lab like Janoshik Analytical provides an unbiased verification that what’s in the vial matches what’s on the label.

Vendors like Chameleon Peptides publish third-party Janoshik COAs for every batch, making it easy to verify purity and identity before you buy. This level of transparency should be your baseline expectation, not a bonus feature.

For a deep dive into interpreting these documents, see our guide to reading peptide COAs.

Purity Testing Methods

A credible COA should include results from at least two analytical methods:

  • HPLC (High-Performance Liquid Chromatography) — Separates the peptide from impurities and quantifies purity as a percentage. Research-grade peptides should be ≥95% pure, with many vendors offering ≥98% or ≥99%.
  • Mass Spectrometry (MS) — Confirms the molecular weight matches the expected value for the target peptide. This verifies you actually received the correct compound, not just a pure something.

Some vendors also provide amino acid analysis, endotoxin testing, or residual solvent testing. While not always necessary, these additional tests indicate a higher level of quality control. To better understand what these purity numbers actually mean, check out this guide on understanding peptide purity.

Proper Labeling and Packaging

Professional vendors label their products clearly with:

  • Peptide name and sequence
  • Net peptide content (in milligrams)
  • Batch/lot number (matching the COA)
  • Storage conditions
  • “For research use only” designation
  • Sealed, crimped vials with intact flip-top caps

If a vendor ships unlabeled vials, uses handwritten labels, or doesn’t include batch numbers, treat that as a red flag.

Website and Communication

Legitimate peptide suppliers typically maintain professional websites with:

  • Detailed product pages listing molecular weight, sequence, and CAS number
  • Publicly accessible COAs (or easy request process)
  • Clear “research use only” disclaimers
  • Responsive customer service
  • Secure payment processing

Red Flags: When to Walk Away

Learning to spot unreliable vendors is just as important as finding good ones. Avoid any vendor that exhibits these warning signs:

No COAs Available

If a vendor can’t or won’t provide a Certificate of Analysis, you have no way to verify what you’re buying. This is non-negotiable — no COA means no purchase.

Suspiciously Low Prices

Peptide synthesis is expensive. Quality raw materials, purification, lyophilization, third-party testing, and proper packaging all cost money. If a vendor is dramatically cheaper than established competitors (50%+ below market), ask yourself what they’re cutting. Usually it’s purity, testing, or both.

That said, high prices don’t guarantee quality either. Use COAs as your primary quality indicator, not price.

Health Claims or Dosing Instructions

Research peptides are sold for in-vitro laboratory use. Any vendor that provides human dosing instructions, makes therapeutic claims, or markets peptides as supplements or treatments is operating outside legal boundaries. This is a serious red flag — both for legality and for the vendor’s overall credibility.

In-House Only Testing

Some vendors provide COAs that appear professional but are generated entirely in-house without independent verification. Look for the testing laboratory’s name, contact information, and accreditation details. If the COA just shows results without identifying who performed the testing, it’s essentially meaningless.

No Batch Numbers

Batch numbers connect a specific vial to a specific COA. Without them, there’s no way to verify that the test results you’re viewing actually apply to the product you received. Every vial should have a traceable batch/lot number.

Vague or Missing Product Information

If a product page doesn’t list the amino acid sequence, molecular weight, or CAS number, the vendor either doesn’t know their product or doesn’t want you to verify it. Either way, move on.

Understanding Purity Percentages

Purity is expressed as a percentage and tells you what proportion of the vial’s contents is actually the target peptide versus impurities. But there are nuances worth understanding:

What the Numbers Mean

  • ≥99% purity — Exceptional. Primarily used for analytical standards and highly sensitive assays.
  • ≥98% purity — High purity. Suitable for most in-vitro research applications.
  • ≥95% purity — Standard research grade. Acceptable for many protocols.
  • <95% purity — Below standard. May contain significant impurities that affect experimental results.

Net Peptide Content vs Total Weight

This catches many beginners. A vial labeled “5 mg” contains 5 mg of total lyophilized material — but not all of that is peptide. The total weight includes:

  • The target peptide
  • Counterions (acetate or TFA salts from synthesis)
  • Residual moisture
  • Trace impurities

The net peptide content — the actual amount of active peptide — is typically 60-80% of the total weight. Quality COAs specify this value, and it’s the number you should use when calculating reconstitution volumes. Our reconstitution calculator accounts for this.

Purity vs Potency

A peptide can be 99% pure but still have low potency if it was degraded, improperly stored, or exposed to conditions that altered its three-dimensional structure. Purity tells you about chemical composition; proper handling and storage ensure the peptide retains its functional activity.

Equipment You’ll Need

Before your peptides arrive, make sure you have these essentials on hand:

Bacteriostatic Water (BAC Water)

This is your primary reconstitution solvent. Bacteriostatic water is sterile water containing 0.9% benzyl alcohol, which prevents bacterial growth and allows multi-use access to the vial over 28 days.

Buy USP-grade bacteriostatic water from a reputable medical supply source. For guidance on choosing the right solvent, see our bacteriostatic water vs sterile water comparison.

Insulin Syringes

Insulin syringes are the standard tool for measuring and transferring peptide solutions. For most applications, you’ll want:

  • 1 mL (100 unit) insulin syringes — the most versatile size
  • 0.5 mL (50 unit) syringes — useful for very small volumes
  • Choose syringes with clear, easy-to-read unit markings

Understanding syringe measurements is critical for accurate dosing. Our insulin syringe units guide explains the relationship between units, milliliters, and how to read your syringe accurately.

Alcohol Swabs

Use isopropyl alcohol swabs (70% IPA) to sterilize vial stoppers before every needle insertion. This is a simple step that dramatically reduces contamination risk. Buy individually wrapped swabs for convenience and sterility.

Proper Storage

You’ll need appropriate cold storage:

  • Freezer (-20°C) for long-term storage of lyophilized (unreconstituted) peptides
  • Refrigerator (2-8°C) for reconstituted peptides in active use

Some researchers also keep desiccant packets (silica gel) with their lyophilized peptides to absorb any ambient moisture. See our peptide storage guide for complete protocols.

  • Nitrile gloves — maintain sterile technique
  • Sharps container — for safe syringe disposal
  • Labels and markers — label reconstituted vials with date, peptide name, and concentration
  • Calculator or our reconstitution calculator — for precise volume and concentration calculations

Proper Storage From Day One

Storage matters from the moment your package arrives. Here’s the protocol:

When Your Package Arrives

  1. Inspect the packaging — check for damage, verify the vial seals are intact
  2. Check the label — confirm peptide name, quantity, and batch number match your order
  3. Review the COA — verify purity, molecular weight, and testing laboratory
  4. Store immediately — place lyophilized vials in the freezer (-20°C) or refrigerator (2-8°C)

Storage Rules

  • Lyophilized peptides: Freezer (-20°C or below) for maximum shelf life. Refrigerator (2-8°C) is acceptable for shorter-term storage.
  • Reconstituted peptides: Refrigerator only. Use within 14-30 days when reconstituted with bacteriostatic water.
  • Protect from light: Many peptides are photosensitive. Store in a dark location or wrap vials in foil.
  • Avoid repeated freeze-thaw cycles: Each cycle degrades the peptide. If you need small amounts over time, consider making aliquots.

For a complete storage protocol, visit our peptide storage guide.

Legality of Research Peptides

Research peptides occupy a specific legal category in most jurisdictions. Here’s the general framework — though you should always verify the specific regulations in your region:

In the United States and many other countries, research peptides are legal to buy, sell, and possess when sold and used for legitimate research purposes. They are classified as research chemicals, not controlled substances (with some specific exceptions).

  • Peptides must be sold “for research use only” or “not for human consumption”
  • Vendors must not make therapeutic or medical claims
  • Buyers should have legitimate research intent
  • Some specific peptides may be regulated differently depending on jurisdiction
  • Import/export regulations vary by country

Researcher Responsibilities

As a buyer, your responsibilities include:

  • Using peptides only for their stated purpose (in-vitro laboratory research)
  • Maintaining proper documentation of purchases and usage
  • Following your institution’s protocols for handling research compounds
  • Disposing of materials according to local regulations

This is not legal advice. If you have questions about specific compounds or regulations in your area, consult with a legal professional or your institution’s compliance office.

Common Mistakes Beginners Make

Learning from others’ errors can save you significant time and money. Here are the most frequent beginner mistakes:

1. Not Checking the COA Before Ordering

Always review the COA before purchasing — or at minimum, confirm that third-party COAs are available. Don’t wait until after the vial arrives to discover the vendor doesn’t provide testing documentation.

2. Using Sterile Water Instead of Bacteriostatic Water

Sterile water is fine for single-use, but it contains no preservative. If you’re accessing the vial multiple times over days or weeks, you need bacteriostatic water to prevent bacterial contamination.

3. Reconstituting the Entire Supply at Once

Reconstituted peptides degrade much faster than lyophilized ones. Only reconstitute what you’ll use in the next 2-4 weeks. Keep the rest in lyophilized form in the freezer.

4. Incorrect Reconstitution Volume

Adding the wrong amount of solvent gives you the wrong concentration, which means every subsequent measurement is off. Use the reconstitution calculator to determine exact volumes before you start.

5. Shaking the Vial

After adding solvent, never shake a peptide vial. Shaking can damage the peptide through mechanical stress and foaming. Instead, gently swirl or roll the vial between your palms until the powder is fully dissolved.

6. Improper Storage

Leaving reconstituted peptides at room temperature, storing lyophilized peptides in a warm area, or repeatedly freezing and thawing vials all accelerate degradation. Follow the storage guidelines in our peptide storage guide.

7. Not Labeling Reconstituted Vials

After reconstitution, immediately label the vial with: peptide name, concentration (mg/mL), date reconstituted, and solvent used. Unlabeled vials lead to confusion, dosing errors, and wasted product.

8. Buying Based on Price Alone

The cheapest peptides are rarely the best value. A vial that costs 30% less but has 80% purity versus 99% means you’re getting far less usable peptide — and introducing more impurities into your research.

9. Skipping Sterile Technique

Every time you access a vial, clean the stopper with an alcohol swab. Use a fresh syringe each time. These small steps prevent bacterial contamination that can ruin your peptides and compromise your research.

10. Not Having a Plan

Before ordering, know what peptides you need, what concentrations your protocol requires, how much you’ll use, and how you’ll store them. A little planning prevents waste and ensures you order the right quantities.

Your First Purchase Checklist

Here’s a quick checklist to reference before placing your first order:

  • Research your peptide — understand its sequence, molecular weight, and typical applications
  • Evaluate the vendor — verify third-party COAs, check reputation, review labeling standards
  • Review the COA — confirm purity (≥95%), mass spec verification, and third-party testing
  • Order supplies — bacteriostatic water, insulin syringes, alcohol swabs
  • Prepare storage — clear freezer/fridge space, have desiccant packets ready
  • Bookmark tools — reconstitution calculator, syringe guide, storage guide
  • Read the reconstitution guide — review the step-by-step process before your peptides arrive
  • Plan your protocol — know your target concentration and usage timeline before reconstituting

Next Steps

Once your peptides arrive and you’re ready to begin:

  1. Reconstitute properly — follow our complete reconstitution guide
  2. Calculate your concentration — use the reconstitution calculator for precise math
  3. Understand your syringes — review the insulin syringe units guide
  4. Store correctly — follow the peptide storage guide
  5. Verify your product — learn to read your COA for every batch

Research peptides are powerful tools for scientific investigation. By starting with the right vendor, the right equipment, and the right knowledge, you set yourself up for reliable, reproducible results from day one.

This article is intended for educational and informational purposes related to in-vitro laboratory research only. Research peptides are not intended for human consumption and are not approved for therapeutic use. Always follow your institution’s protocols and applicable laws when purchasing and handling research compounds.