Beyond the Label: Understanding Peptide Research, Purity, and Analytical Testing

A vial label gives you three pieces of information at most: a name, a quantity and a purity figure. None of them, on its own, tells you what is actually in the vial.

Anyone who has spent time at the bench knows this. Two suppliers can ship the same sequence, both labelled 10 mg at 99% purity, and the material can still behave differently in an assay. One lot may carry a heavier salt load. Another may hold a closely related impurity that a single HPLC run never separated. A third may arrive with a certificate of analysis that was never tied to that batch at all.

This guide looks at what sits behind those numbers. We start with how research peptides are made, then explain what purity really measures and why net peptide content matters just as much. From there we go through the analytical tests that give you real evidence, how to read a certificate of analysis (COA) critically, and how to keep a good peptide from degrading once it reaches your freezer.

A note on scope: everything here relates to peptides supplied for laboratory and in vitro research. These materials are not approved by Health Canada for human or veterinary use, and nothing in this article is guidance on personal use.

What Are Research Peptides?

Peptides are short chains of amino acids joined by amide bonds, usually called peptide bonds. Most chemists put the upper limit at around 50 residues. Below that, you are working with a peptide; above it, you are usually in protein territory. The cut-off is a convention rather than a strict rule, and different textbooks draw it in slightly different places.

Peptides versus proteins

Length is only part of the difference. Proteins generally fold into stable three-dimensional structures, and that shape is what drives their function. Many peptides, by contrast, are flexible in solution and only adopt a defined shape when they bind a target.

The way they are made also differs. Proteins are mostly produced in living systems such as bacteria, yeast or mammalian cells. Peptides of research length are usually built chemically, one amino acid at a time. That chemical route is what makes them so easy to modify, and it is also where most of their impurities come from.

Why peptides are useful in the lab

Peptides are precise tools. A researcher can change a single residue, add a fluorescent label, attach biotin or cyclize the chain, then measure exactly what that change does. That level of control is hard to match with larger biomolecules.

Common applications include:

• Receptor binding and ligand displacement studies
• Enzyme assays, where peptides serve as substrates or inhibitors
• Cell signalling models in vitro
• Epitope mapping and antibody production
• Structure-activity relationship (SAR) work, where small sequence changes are compared side by side

In every one of these, the result is only as reliable as the peptide that went into it.

What “Research Use Only” means

A Research Use Only (RUO) label states that the material is intended for laboratory investigation. It is not intended for diagnostic or therapeutic use, or for human or animal consumption. RUO products are also not necessarily made under Good Manufacturing Practice (GMP) conditions, which is the standard for pharmaceutical ingredients.

That does not mean RUO material should be held to a low standard. If anything, the opposite is true. Without GMP oversight, the analytical data a supplier provides is often the only real evidence a researcher has about quality.

How Research Peptides Are Made

Almost every research peptide on the market is produced by solid-phase peptide synthesis (SPPS). The method was developed by Bruce Merrifield in the 1960s, and it earned him the Nobel Prize in Chemistry in 1984. The basic idea has not changed much since: anchor the first amino acid to a solid support, then build the chain one residue at a time.

Solid-phase synthesis: Fmoc and Boc chemistry

The chain grows on tiny resin beads. Each amino acid arrives with a temporary protecting group on its amino end, so only one coupling can happen per cycle. Reactive side chains carry their own, more permanent protecting groups.

Today most labs use Fmoc chemistry. A typical cycle looks like this:

1. Remove the Fmoc group from the growing chain, usually with piperidine.
2. Wash the resin.
3. Add the next protected amino acid along with a coupling reagent.
4. Wash again, then repeat for the next residue.

The older Boc chemistry uses acid for each deprotection step and hydrogen fluoride for the final cleavage. It is still used for some difficult sequences, but the harsh reagents have made Fmoc the default.

No coupling step is perfect, and the losses add up quickly. If each coupling is 99% efficient, a 30-residue peptide comes out at roughly 74% full-length product in theory. At 98% per step, that drops to about 55%. Everything else in the crude mixture is a near-copy of the target that is missing one or more residues.

Cleavage and deprotection

Once the sequence is complete, the peptide is released from the resin with a strong acid, usually trifluoroacetic acid (TFA). Small molecules called scavengers are added to the cleavage mixture to trap reactive fragments before they can damage sensitive residues.

The same step strips off the side-chain protecting groups. What remains is crude peptide: the target sequence mixed with deletion products, partly deprotected species and other by-products.

Purification by preparative HPLC

Crude peptide is purified by preparative reverse-phase high-performance liquid chromatography (RP-HPLC). The sample runs through a column under a gradient of water and acetonitrile, usually with a small amount of TFA. Fractions are collected, tested and pooled only if they meet the purity target.

This is where purity is won or lost. Tighter fraction cuts give higher purity but lower yield, and that trade-off shows up directly in price.

Lyophilization

The pooled fractions are freeze-dried to remove water and solvent. The result is the white, fluffy powder most researchers recognize. Unless the supplier performs a salt exchange, that powder is a TFA salt, because TFA from the purification step binds to the peptide’s basic groups.

Every stage of this process can introduce impurities. That is exactly why analytical testing of the final lot matters.

What “Purity” Actually Means

When a COA lists a peptide as 98% pure, it almost always means HPLC purity. That figure is the area of the main peak divided by the total area of all peaks detected, usually at a UV wavelength of 214 or 220 nm, where the peptide bond absorbs strongly.

Purity is a relative measure

HPLC purity only compares the things the detector can see. It tells you how much of the UV-absorbing material is your target sequence versus related peptide species. It does not count water, and it does not account for most salts or counterions in the powder.

So a 98% figure does not mean 98% of the vial’s weight is your peptide. It means that, among the peptide species the method separated and detected, about 98% of the signal came from the main peak.

Common purity grades and where they fit

Suppliers generally offer peptides at set purity levels. The right grade depends on what the experiment demands, not on getting the highest number possible.

Purity grade	Typical research use
Crude or desalted (below 70%)	Early screening, peptide arrays
70% or higher	Antibody production, ELISA standards
85% or higher	Semi-quantitative work, enzyme-substrate studies
95% or higher	Quantitative in vitro assays, receptor-ligand studies, bioassays
98% or higher	Structural work such as NMR and crystallography, sensitive quantitative studies

Higher purity costs more because it means tighter fraction cuts and lower yield. For many cell-based assays, 95% is the practical standard.

Why “99%+” needs context

A purity number is only meaningful alongside the method that produced it. The same sample can return different results depending on:

• The gradient. A steep gradient compresses peaks together, so impurities can hide under the main peak. A shallow gradient separates them.
• The column. Different stationary phases resolve different impurities.
• The wavelength. Some impurities absorb more or less at a given wavelength than the target.
• Integration settings. Where the analyst draws the baseline, and the threshold below which small peaks are ignored, both shift the final percentage.

There is also the problem of co-elution. A deletion sequence missing one residue can behave almost identically to the full-length peptide on a column. If it elutes under the main peak, the purity figure looks better than the material really is. This is why mass spectrometry data should always sit alongside HPLC results.

Purity, quantity and activity are three different questions

These terms are often used interchangeably, and they should not be.

• Purity asks what fraction of the peptide material is the correct sequence.
• Quantity asks how much actual peptide is in the vial by weight. That is net peptide content, covered next.
• Activity asks whether the peptide does what it should in a biological system. That depends on the correct sequence, stereochemistry and, in some cases, folding or disulfide bonding. HPLC does not measure it.

A peptide can be highly pure and still be present in a smaller amount than the label suggests. It can also be pure and present in the right amount but carry the wrong stereochemistry at one residue, which changes how it behaves.

Purity vs. Net Peptide Content

Of all the numbers on a COA, this is the distinction researchers most often miss. Purity tells you how clean the peptide is. Net peptide content (NPC) tells you how much of the powder is peptide in the first place.

What else is in the vial

A lyophilized peptide is never 100% peptide by weight. Alongside the target sequence and its related impurities, the powder also contains:

• Counterions. Basic groups on the peptide, such as the N-terminus and the side chains of lysine, arginine and histidine, carry a positive charge. Negatively charged counterions, most often trifluoroacetate or acetate, pair with them.
• Bound water. Lyophilized peptides are hygroscopic and pick up moisture from the air. Water content of several percent is normal.
• Residual salts. Small amounts can remain from purification.

The more basic residues a sequence has, the more counterions it carries, and the lower its net peptide content tends to be.

Net peptide content in practice

NPC is the percentage of the powder’s total weight that is peptide. For most research peptides, it falls somewhere between 60% and 90%.

Here is how purity and NPC work together. Take a vial with a gross weight of 10 mg, an NPC of 75% and an HPLC purity of 98%:

Target peptide = 10 mg × 0.75 × 0.98 = 7.35 mg

That vial holds about 7.4 mg of the correct sequence, not 10 mg. If you prepare a stock solution by assuming the full 10 mg is peptide, your working concentration is overstated by roughly 36%. In a dose-response study, that error carries through every data point.

It is also worth asking how a supplier labels fill weight. Some state the gross weight of powder; others state the net peptide amount. The COA should make clear which one you are looking at.

How NPC is measured

There are two main methods:

• Amino acid analysis (AAA). The peptide is hydrolyzed into its individual amino acids, which are then measured. Comparing the result to the expected sequence gives both composition and the amount of peptide present.
• Elemental nitrogen analysis. Since nitrogen comes almost entirely from the peptide itself, measuring total nitrogen gives a reliable estimate of peptide content.

For sequences containing tryptophan or tyrosine, UV absorbance at 280 nm can provide a quick check, though it is less precise than either method above.

If a COA lists purity but no NPC, you know how clean the material is but not how much of it you have.

Types of Peptide Impurities

The impurities in a peptide sample are rarely random. Most are predictable by-products of synthesis, cleavage or storage, and many carry a mass signature that makes them easy to spot once you know what to look for.

Impurity	How it forms	How it shows up
Deletion sequences	A coupling step fails, so one residue is skipped	Mass lower by one residue; often elutes very close to the main peak
Truncated sequences	The chain stops growing partway through synthesis	Shorter fragments, usually well separated on HPLC
Incomplete deprotection	A side-chain protecting group survives cleavage	Mass higher than expected, e.g. +56 Da for a leftover tBu group or +252 Da for Pbf on arginine
Aspartimide formation	Aspartic acid cyclizes during Fmoc synthesis, especially in Asp-Gly sequences	Mass 18 Da lower; can lead to further rearranged by-products
Oxidation	Methionine, cysteine or tryptophan reacts with oxygen	+16 Da per oxidized methionine; often grows during storage
Deamidation	Asparagine or glutamine converts to aspartic or glutamic acid	+1 Da; common in Asn-Gly sequences and in solution
Racemization	An L-amino acid converts to its D-form	Same mass as the target; needs a chiral method to detect
Dimers and aggregates	Chains link through disulfide bonds or clump together	Higher-mass species; may cause poor solubility or cloudy solutions

Two of these deserve extra attention. Deletion sequences are hard to remove because they are so similar to the target, and they can co-elute under the main HPLC peak. Racemized peptides are harder still: they share the exact mass of the correct sequence, so routine MS will not flag them, and standard HPLC may not separate them.

Contaminants that are not peptides

Some impurities have nothing to do with the sequence itself:

• Residual solvents such as acetonitrile, dichloromethane or DMF left over from synthesis and purification
• Heavy metals picked up from reagents or equipment
• Endotoxins, which are lipopolysaccharides from the outer membrane of gram-negative bacteria, introduced through water, glassware or handling

These will not appear on a standard HPLC chromatogram. If your work involves cell culture or live systems, they can matter as much as peptide purity, and they need their own tests.

The Analytical Testing Toolkit

No single test can confirm that a peptide is what it claims to be, at the purity claimed, in the amount claimed. Good quality control relies on orthogonal methods: techniques that measure different properties, so the weaknesses of one are covered by another.

HPLC (high-performance liquid chromatography)

Analytical reverse-phase HPLC is the standard purity test. The sample is injected onto a column, most often a C18 stationary phase, and eluted with a gradient of water and acetonitrile. Peptides separate by hydrophobicity, and a UV detector at 214 to 220 nm records each as a peak.

When you read a chromatogram, look for:

• One dominant main peak at a consistent retention time
• Small impurity peaks on either side, with their area percentages listed
• Method details: column type, gradient, flow rate and wavelength
• A clean, flat baseline with no unexplained humps

The key limitation is that HPLC measures purity, not identity. A sharp single peak tells you the sample is clean. It does not tell you that it is the right peptide.

Mass spectrometry (MS)

Mass spectrometry confirms identity by measuring molecular weight. The two techniques you will see most often are:

• ESI-MS (electrospray ionization). Produces multiply charged ions, so a single peptide shows up as a series of peaks such as [M+2H]2+ and [M+3H]3+. Software converts these back to the intact mass.
• MALDI-TOF (matrix-assisted laser desorption/ionization, time of flight). Usually produces singly charged [M+H]+ ions, which makes spectra simpler to read.

A good COA lists the theoretical mass calculated from the sequence alongside the observed mass. They should agree closely; for small peptides, within about 1 Da is typical for routine instruments. Extra peaks at predictable offsets, such as +16 Da or minus one residue, point to specific impurities.

LC-MS

LC-MS couples an HPLC system directly to a mass spectrometer. Each peak on the chromatogram gets its own mass reading, so you can see not just that an impurity exists but what it is. It is the most informative single run available for routine peptide QC.

Amino acid analysis (AAA)

AAA breaks the peptide down into its component amino acids by acid hydrolysis, then measures each one. It confirms that the composition matches the expected sequence and gives an accurate figure for net peptide content. It does not confirm the order of the residues.

Endotoxin testing (LAL assay)

The Limulus amebocyte lysate (LAL) assay detects bacterial endotoxins. Results are reported in endotoxin units per milligram (EU/mg). Endotoxins can trigger strong immune responses in cell cultures and animal models, even at very low levels, so this test matters for any work beyond simple biochemical assays.

Water content (Karl Fischer titration)

Karl Fischer titration measures the water in a lyophilized sample. It feeds directly into net peptide content calculations and helps explain why two lots of the same peptide can differ in actual peptide mass.

Counterion analysis

Ion chromatography or other methods can quantify TFA or acetate content. This is useful when TFA might interfere with an assay, since residual TFA has been reported to affect some cell-based experiments. It is also needed to confirm a salt exchange was actually carried out.

Residual solvents and heavy metals

Residual solvents are usually measured by gas chromatography (GC), often with headspace sampling. Heavy metals are typically measured by inductively coupled plasma mass spectrometry (ICP-MS). The pharmaceutical guidelines ICH Q3C and Q3D set out accepted limits and are a useful reference, even for RUO material.

Sterility testing

Lyophilized research peptides are not usually sold as sterile. Sterility testing is relevant only when a supplier specifically claims it, and in that case the claim should be backed by a documented method and result.

At a glance: what each test tells you

Test	What it measures	Why it matters
RP-HPLC	Purity relative to other peptide species	Shows how clean the material is
Mass spectrometry	Molecular weight	Confirms you have the right peptide
LC-MS	Purity and mass of each peak	Identifies what each impurity is
Amino acid analysis	Composition and peptide content	Confirms makeup and actual peptide mass
LAL assay	Bacterial endotoxins	Protects cell and in vivo work from false signals
Karl Fischer	Water content	Supports accurate concentration calculations
Counterion analysis	TFA or acetate content	Flags possible assay interference
GC and ICP-MS	Residual solvents and metals	Detects non-peptide contaminants

At a minimum, every research peptide should come with HPLC and MS data. Anything less leaves the most basic question, whether this is the right molecule, unanswered.

How to Read a Certificate of Analysis (COA)

A COA is the supplier’s record of what was tested, how, and with what result. Read properly, it can tell you a great deal about a lot. Read quickly, it can give you false confidence.

Anatomy of a COA

A complete certificate should include:

• Product identity: peptide name, full amino acid sequence, molecular formula and, where available, CAS number
• Lot or batch number: unique to the production run
• Dates: manufacture date, test date and, ideally, a retest or expiry date
• Methods: the analytical techniques used, with key conditions
• Specifications and results: what the lot was required to meet, and what it actually achieved
• Raw data: the HPLC chromatogram and mass spectrum, not just summary figures
• Lab details: the name of the testing laboratory and a signature or approval from the responsible analyst

Match the COA to the vial

This step sounds obvious, and it is often skipped. The lot number on the COA must match the lot number on your vial. If the vial has no lot number, or the COA is a generic product sheet with no batch reference, the document tells you nothing about the material in your hands.

Complete versus bare-minimum COAs

Element	Bare-minimum COA	Complete COA
Purity	A single percentage	Percentage plus the full chromatogram and method
Identity	“Conforms”	Theoretical and observed mass, with the spectrum
Peptide content	Not listed	Net peptide content and method used
Water and counterions	Not listed	Karl Fischer result and counterion type or content
Endotoxin	Not listed	Result in EU/mg, where relevant
Traceability	Product name only	Lot number, dates, lab name and analyst sign-off

COA red flags

Treat a certificate with caution if you notice any of the following:

• No lot number, or the same COA supplied for every order over months
• A purity figure with no chromatogram to support it
• No mass spectrometry data confirming identity
• Suspiciously neat numbers, such as 99.9% across every product in a catalogue
• A chromatogram that does not match the stated result, for example visible impurity peaks that add up to more than the claimed percentage allows
• An observed mass that does not match the sequence, or a spectrum with an obviously different scale
• No laboratory name, address or contact, so there is no way to verify the report
• Dates that do not add up, such as a test date after the shipping date, or a COA years older than the stock
• Signs of editing, including mismatched fonts, misaligned text or images that look copied from another report

One red flag does not always mean the material is bad. It does mean you should ask the supplier for clarification, or have the material tested independently before relying on it.

In-House vs. Third-Party Testing

Who performed the analysis matters almost as much as what the analysis shows.

Manufacturer-supplied COAs

Most peptides ship with a COA produced by the manufacturer’s own QC lab. That is standard practice, and a well-run in-house lab can produce excellent data. The limitation is independence. The same organization that made the product is also reporting on its quality, and buyers have no direct way to check the work.

This matters more when a product passes through several hands. A peptide may be synthesized in one country, repackaged by a distributor and sold by a retailer, each passing along the original COA. By the time it reaches the lab, the document may not describe the lot in the vial.

Independent third-party labs

Third-party testing means a separate, unaffiliated laboratory analyzes a sample from the lot. Because the lab has no stake in the result, its report carries more weight. Many reputable suppliers now commission third-party testing for each batch and publish the reports.

When assessing a third-party report, check that:

• The lab is named and can be contacted
• The report references the same lot number as your vial
• The sample was taken from finished, packaged stock, not a separate reference sample
• Both HPLC and MS were performed

Lab accreditation: ISO/IEC 17025

ISO/IEC 17025 is the international standard for the competence of testing and calibration laboratories. An accredited lab has been independently assessed on its methods, equipment calibration, staff training and quality management. In Canada, labs are accredited to this standard by the Standards Council of Canada (SCC) and the Canadian Association for Laboratory Accreditation (CALA).

Accreditation applies to specific methods, so it is worth checking that the tests on your report fall within the lab’s accredited scope. Accreditation is not a guarantee of a perfect result, but it does mean the lab works to an audited standard.

Verifying a report

Some labs and suppliers make verification simple. Look for:

• A unique report ID that can be checked on the lab’s own website
• A QR code on the COA linking to the original report hosted by the lab
• Direct confirmation from the lab by email, if no online tool is available

If a supplier is unwilling to let you verify a report, that tells you something too.

Batch-specific versus generic testing

A single test performed once on a product, then reused for every subsequent batch, is not quality control. Synthesis and purification vary from run to run. The only meaningful report is one tied to the specific lot you received.

Stability, Storage, and Handling

A peptide that tests at 98% on release will not stay at 98% if it is stored badly. Most of the degradation researchers run into happens after the COA was issued, in shipping, in storage or during reconstitution.

Storing lyophilized peptides

In dry, powdered form, most peptides are reasonably stable. To keep them that way:

• Store at −20 °C for routine use, or −80 °C for long-term storage
• Keep vials tightly sealed and away from light
• Store with a desiccant where possible, since moisture speeds up most degradation pathways
• Let the vial reach room temperature before opening, so condensation does not form on the cold powder

Short periods at room temperature, such as during shipping, are generally well tolerated by lyophilized material. Extended exposure to heat and humidity is not.

Reconstitution basics for lab work

The right solvent depends on the sequence. A few general principles apply:

• Start with sterile water or a suitable buffer for most hydrophilic peptides.
• Basic peptides, with many lysine or arginine residues, often dissolve more easily in a dilute acidic solution such as 0.1% acetic acid.
• Acidic peptides may dissolve better in a dilute basic buffer.
• Hydrophobic peptides may need a small amount of an organic solvent such as DMSO first, then gradual dilution with aqueous buffer. Check that the solvent is compatible with your assay.
• Bacteriostatic water, which contains 0.9% benzyl alcohol, slows microbial growth in solutions that will be accessed repeatedly. Benzyl alcohol can interfere with some cell-based assays, so consider whether it suits your work.

Always test solubility on a small portion before dissolving the whole vial.

What breaks peptides down

• Moisture drives hydrolysis and deamidation.
• Oxygen and light promote oxidation of methionine, cysteine and tryptophan.
• Repeated freeze-thaw cycles can cause aggregation and loss of material. Divide stock solutions into single-use aliquots before freezing.
• pH extremes speed up deamidation and hydrolysis. A pH of roughly 5 to 6 suits many peptides in solution.
• Microbial contamination can degrade peptides quickly in non-sterile solutions.

Shelf life: powder versus solution

Lyophilized peptides stored correctly at −20 °C can remain stable for a year or more, and often considerably longer. Once in solution, stability drops sharply. Many peptides last only days to a few weeks refrigerated at 2 to 8 °C, and frozen aliquots typically hold for a few months. Sequences containing cysteine, methionine, tryptophan, asparagine or glutamine are usually the least stable in solution.

The practical rule is simple: keep peptides dry and cold for as long as possible, and only make up what you need.

Why Purity Matters for Research Integrity

It is tempting to treat reagent quality as a purchasing detail. In practice, it shapes whether your results mean anything.

Reproducibility

Reproducibility problems in biomedical research are well documented, and poorly characterized reagents are one recognized cause. If one lot of a peptide is 97% pure and the next is 88%, an experiment repeated a month later is no longer the same experiment. Without lot-specific data, there is no way to tell whether a change in results reflects the biology or the material.

Off-target effects

Impurities are not always inert. A deletion sequence or an oxidized variant may still bind the target receptor, only with different affinity. It may also act on something else entirely. In a sensitive assay, even a few percent of an active impurity can shift a dose-response curve or create a signal that is not really there.

Endotoxin contamination is a particular risk in cell work. Low levels of endotoxin can activate immune cells and trigger cytokine release, which can easily be mistaken for an effect of the peptide itself.

Accurate concentrations

As the net peptide content example showed, ignoring NPC can overstate concentration by a third or more. That error affects calculated values such as EC50 and IC50, and it makes comparisons with published work unreliable.

The real cost of poor material

A cheaper peptide that fails is rarely cheaper in the end. The true cost includes:

• Wasted cell lines, antibodies and other reagents
• Weeks of lost instrument and staff time
• Results that cannot be published or have to be retracted
• Follow-up work built on a false lead

Compared with these, the price difference between a well-characterized peptide and a poorly documented one is usually small.

A Researcher’s Quality Checklist

Before a new peptide lot goes into an experiment, run through these questions:

• Is there a batch-specific COA with a lot number that matches the vial?
• Does the COA include the full HPLC chromatogram, with method details?
• Is identity confirmed by mass spectrometry, with theoretical and observed mass listed?
• Is net peptide content stated, along with the method used?
• Are water content and counterion type reported?
• Was testing done or confirmed by an independent, accredited laboratory?
• Can the report be verified through the lab directly?
• Is endotoxin data provided, if the work involves cells or live systems?
• Are storage and shipping conditions documented, and did the vial arrive in good condition?
• Does the purity grade suit the application you have in mind?

If you cannot tick most of these boxes, consider requesting more data or arranging independent testing before relying on the material.

Conclusion

A label is a claim. Analytical data is the evidence behind it.

When you assess a research peptide, you are really asking three separate questions. Is it the right molecule? How clean is it? How much of it is actually in the vial? HPLC answers the second. Mass spectrometry answers the first. Net peptide content, supported by amino acid analysis or nitrogen testing, answers the third. A complete, batch-specific COA from a verifiable laboratory brings all three together.

None of this is about distrusting every supplier. It is about knowing what good documentation looks like, so you can recognize it when you see it and ask the right questions when you do not. Careful handling after delivery finishes the job, since the best-characterized peptide will not stay that way in a warm, damp drawer.

Good research starts with knowing exactly what went into the experiment. That knowledge begins well beyond the label.

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This article is for educational and informational purposes only. Research peptides are intended strictly for laboratory and in vitro research and are not approved by Health Canada for human or veterinary use.