What Is Bioburden Testing? Microbial Enumeration, CFU Counts and Sterilization Validation

Published November 2026 · Patriot Labs Research Team · ~20 min read

The short answer

Bioburden testing is the measurement of the number of viable microorganisms — bacteria, yeasts and moulds — living on or in a material before it is sterilised or released. The organisms are recovered from the sample, grown on nutrient media under defined conditions, and counted, with the result expressed in colony-forming units (CFU) per gram, per millilitre or per device. It is a count of how much living contamination is present, not a test of identity, potency or chemical purity.

The word carries two closely related meanings. In pharmaceutical work, bioburden testing is essentially the microbial enumeration test for non-sterile products described in United States Pharmacopeia General Chapter <61>, which reports a total aerobic microbial count and a total yeast and mould count.^[1] In medical-device manufacturing, bioburden testing is the determination of the microbial population on a product before terminal sterilisation, standardised worldwide by ISO 11737-1.^[4] The mechanics are the same in both: recover, grow, count.

What a bioburden number is for is the key to understanding it. A low, stable count tells a manufacturer that its raw materials, water, equipment and handling are under control, and — for anything that will be sterilised — it tells the sterilisation process how many organisms it has to kill. That second use is why the measurement matters so much: the dose of radiation, the length of a steam cycle or the exposure to ethylene oxide is set against the bioburden the product actually carries. This guide works through what bioburden is, how it is recovered and counted, how the numbers are defined and corrected, how they feed sterilisation, and how a bioburden figure sits alongside the other numbers on a research certificate of analysis.

What bioburden actually is

Bioburden is the population of viable microorganisms on or in a product, component, raw material or package.^[4][8] The two words that do the work are population and viable. Population means a count — a number of organisms, not a yes-or-no — and viable means able to grow and reproduce, because the only organisms a culture-based test can count are the ones that form a visible colony when given food and warmth.

That definition sets the boundaries of the measurement precisely. Bioburden counts living bacteria, yeasts and moulds. It does not count viruses, prions or protozoa, which is why ISO 11737-1 states explicitly that viral, prion and protozoan enumeration are outside its scope.^[4] It does not count dead cells, and it does not count the molecules those cells leave behind — most importantly bacterial endotoxin, the heat-stable fragment of the Gram-negative cell wall that is measured by its own test and discussed in Endotoxin Testing Explained. A sample can carry a large load of endotoxin and return a bioburden count of zero, because the bacteria that shed it are dead. The two tests answer different questions and neither substitutes for the other.

The organisms a product carries come from everywhere it has been. For a manufactured article, ISO 11737-1 lists the sources as the raw materials, the manufacturing process, the assembly steps, the manufacturing environment, any assembly aids, the cleaning processes and the finished-product packaging.^[4] Microbes are not introduced by a single lapse; they accumulate from water, air, surfaces and handling along the whole route from ingredient to sealed container. Bioburden is the sum of that accumulation at the moment the sample is taken, which is why it is measured late in the process, on material that is as close as possible to the finished, packaged state.

Why bioburden is measured at all

Bioburden is measured for two distinct reasons, and the figure means something slightly different depending on which one applies: process control, and sterilisation.

The first reason is control of a non-sterile product. Many legitimate products are not sterile and are never meant to be — oral tablets, topical creams, inhaled powders, cosmetics, purified water. For these, the question is not whether any organism is present but whether too many are, and whether any of the dangerous ones are. A rising microbial count is an early warning that a water system, a raw-material supplier or a cleaning procedure has drifted out of control, often before anything else shows it. United States federal regulations make this explicit for drugs: 21 CFR 211.110(a)(6) requires in-process control procedures that include bioburden testing during manufacture where appropriate.^[8]

The second reason is sterilisation. For anything that will be terminally sterilised — a surgical instrument, an implant, a single-use device — the bioburden is the input to the sterilisation process. The process has to reduce the living population to an acceptably small probability of survival, and it cannot be designed sensibly without knowing how large that population is and how resistant it is to the method being used. Here the bioburden number is not a pass/fail attribute of the product so much as a design parameter for the step that follows. ISO 11737-1 is written primarily to serve this purpose, and it lists validating sterilisation, controlling manufacturing, monitoring raw materials and assessing cleaning efficiency as the uses of a bioburden determination.^[4]

In both cases the measurement earns its place because nothing else catches the same thing. A chemical identity test, a potency assay and a purity figure can all pass on a sample that is heavily contaminated with living microorganisms, because those methods are blind to biology. Only a culture-based count sees the organisms themselves.

Step one: recovering the organisms

Before anything can be counted it has to be recovered, and recovery is the part of a bioburden test where most of the uncertainty lives. The goal is to get the microorganisms off or out of the sample and into a suspension or onto a filter without killing them and without adding any from the outside.

How that is done depends on the sample. A water-soluble substance can simply be dissolved; the pharmacopeial buffers used for this include buffered sodium chloride–peptone solution at pH 7.0, phosphate buffer at pH 7.2, and soybean–casein digest broth.^[8] A solid or a device is treated more aggressively to dislodge organisms adhering to its surfaces: the common techniques are vortexing, ultrasonication in a bath, stomaching (mechanical paddling in a bag of fluid), and rinsing or flushing a fluid pathway.^[2][16] Direct swabbing or a contact plate is used where none of these will work, and swab and contact-plate methods are also how surfaces are assessed in a compounding setting.^[8] Whatever the technique, the governing rule is that the method must neither introduce microorganisms into the sample nor kill those already in it.^[8]

Many products actively fight the organisms being counted, because they are preserved, antimicrobial, or simply hostile to microbial growth. If that activity is carried through to the plate it will suppress colonies and make the count read falsely low. The test defends against this by neutralising the antimicrobial activity — with specific chemical neutralisers, by dilution, or by membrane filtration that lets the product be rinsed away while the organisms stay on the filter — and the choice has to be justified and documented.^[12] Demonstrating that the recovery scheme genuinely neutralises the product’s antimicrobial activity is the central aim of the method-suitability work described below.

Step two: counting — filtration, plate counts and MPN

Once the organisms are in a recoverable form they are enumerated, and there are three standard ways to do it, chosen according to how many organisms are expected and how the sample behaves.^[12]

Membrane filtration passes a measured volume of the sample suspension through a sterile membrane with a pore size of 0.45 micrometres or smaller, which traps the microorganisms on its surface.^[8] The membrane is then laid on an agar plate and incubated, and the colonies that grow on it are counted. Filtration is the preferred method when the expected count is low, because a large volume can be concentrated onto one filter, and when the product is antimicrobial, because the membrane can be rinsed to wash the inhibitory substance away before incubation.^[12]

Plate-count methods put a measured portion of the suspension directly onto or into the agar. In the pour-plate method the sample is mixed with molten agar in a dish and allowed to set, so colonies grow both on and below the surface; in the spread-plate method a small volume is spread across the surface of a set plate. Both are read as colony-forming units after incubation, and a dilution factor is applied: ten colonies grown from 1 mL of a 1-in-10 dilution, for example, correspond to 100 CFU/mL in the original sample.^[14]

The most-probable-number (MPN) method is a statistical estimate rather than a direct count. The sample is distributed across replicate tubes of broth at several dilutions, the tubes that show growth are tallied, and the pattern of positives is read against a statistical table to estimate the original population. MPN is reserved for products with a very low expected bioburden, where it may be the only workable approach, and it is explicitly the least precise of the three — its result is an estimate with wide confidence limits, not a count.^[8]

The media and incubation: TAMC and TYMC

A bioburden test by the pharmacopeial method is really two counts run in parallel, because bacteria and fungi grow best on different food and at different temperatures. The two counts are the total aerobic microbial count and the total yeast and mould count, and they are what USP <61> reports.^[1][12]

The total aerobic microbial count (TAMC) is the count of aerobic bacteria. It is grown on soybean–casein digest agar — a general-purpose medium also sold as tryptic (or trypticase) soy agar, the same substance under two names — and incubated at 30 to 35 °C for three to five days.^[12] The total yeast and mould count (TYMC) is the count of fungi. It is grown on Sabouraud dextrose agar, a more acidic, sugar-rich medium that favours yeasts and moulds over bacteria, and incubated cooler and longer, at 20 to 25 °C for five to seven days.^[12] The cooler temperature and the selective medium let the slower-growing fungi be read without being overrun by bacteria.

Before any of these counts can be trusted, the laboratory runs a one-time study called method suitability (or the growth-promotion and recovery check). A small, defined challenge — no more than 100 CFU of each of a panel of reference strains, added individually rather than as a mixture — is put through the whole recovery and counting scheme, and the colonies recovered are compared with a control that contains no product. For an enumeration test the recovery in the presence of the product must not differ from the control by more than a factor of two.^[12] The standard panel of challenge organisms names a Gram-positive coccus (Staphylococcus aureus ATCC 6538), a Gram-negative rod (Pseudomonas aeruginosa ATCC 9027), a spore-forming bacillus (Bacillus subtilis ATCC 6633), a yeast (Candida albicans ATCC 10231) and a mould (Aspergillus brasiliensis ATCC 16404), so that the method is shown to recover each broad class of organism.^[12] Method suitability is run once in the life of a product, before routine testing begins, and repeated only when the product or process changes.^[13]

Recovery efficiency and the correction factor

No recovery method pulls every organism off a surface, and a bioburden count is only as good as the fraction it recovers. This is handled openly, by measuring that fraction and correcting for it, rather than by pretending recovery is complete. The fraction is called the recovery efficiency, and its reciprocal is the correction factor.^[2][16]

ISO 11737-1 describes two ways to establish recovery efficiency. In the repetitive-recovery (exhaustive) method, the same sample is extracted several times in succession and the organisms recovered at each pass are counted; because each pass removes fewer than the last, the series can be used to estimate how many were left behind on the first. Recovery efficiency is then the count from the first extraction divided by the total recovered across all the passes.^[2] In the inoculated (product-seeded) method, a known number of a reference organism — often a dried spore preparation — is applied to the product and then recovered by the routine technique, and recovery efficiency is the number recovered divided by the number applied.^[2] The repetitive method is unsuitable for powders, gels and materials that dissolve, because the sample does not survive repeated extraction.^[2]

Whichever approach is used, the result is a fraction between zero and one, and the correction factor is simply its reciprocal: a recovery efficiency of 0.5 (half the organisms recovered) gives a correction factor of 2, so the raw plate count is doubled to estimate the true population.^[2] In a full device calculation the corrected bioburden is the raw count multiplied together by the correction factor, the dilution factor and, where only part of a product is tested, the sample-item-portion (SIP) factor that scales the tested portion up to the whole article.^[16] The correction is not a fudge; it is the mechanism by which an imperfect recovery is turned into a defensible estimate, and stating the recovery efficiency is how a laboratory makes the limitation of its own method visible.

CFU, limits and the USP <1111> acceptance criteria

Bioburden is reported in colony-forming units. A colony-forming unit is one unit — a single cell, or a clump of cells that were stuck together — that grows into one visible colony, and the term is deliberately cautious: it counts colonies, not organisms, because a clump of ten cells that lands as one spot grows into one colony and is counted once. Results are expressed per gram, per millilitre or per device so that they can be compared against a defined limit.^[8][14]

For non-sterile pharmaceutical products, the limits themselves live in USP General Chapter <1111>, which sets acceptance criteria by route of administration.^[3] The criteria are written as powers of ten, and the chapter defines how to read them: a limit of 10¹ means a maximum acceptable count of 20, 10² means a maximum of 200, and 10³ means a maximum of 2000.^[3] In other words the stated power of ten is rounded up to the next whole order for judging an individual result. A selection of the criteria gives the flavour:

Two things in that table are worth drawing out. First, the limit tightens as the route becomes more vulnerable: an aqueous oral liquid, which supports growth and is swallowed, is held ten times tighter than a dry non-aqueous preparation. Second, the acceptance criteria are not only about total numbers; most routes also require the absence of specified objectionable organisms. Those presence/absence tests — for Escherichia coli, Salmonella, Pseudomonas aeruginosa, Staphylococcus aureus, bile-tolerant Gram-negative bacteria, Candida albicans and clostridia — are a separate procedure, USP <62>, run alongside the enumeration count rather than as part of it.^[12] For medical devices the governing number is different again, and bioburden is judged not against a fixed CFU limit but against the needs of the sterilisation process that follows.

Bioburden and sterilization: SAL and dose-setting

The most consequential use of a bioburden count is as the starting point for sterilisation, and understanding that link explains why the number is measured so carefully. Terminal sterilisation does not promise that every organism is dead; it promises that the probability of a surviving organism is vanishingly small, and that probability is quantified as the sterility assurance level.

A sterility assurance level (SAL) is the probability that a single unit remains non-sterile after it has been through the sterilisation process.^[9] Because it is a probability it is always a number between zero and one, written with a negative exponent, and the convention for devices that will contact broken skin or the bloodstream is an SAL of 10⁻⁶ — a one-in-a-million chance that any given unit still carries a viable organism.^[9][10] The European standard EN 556 uses the same 10⁻⁶ threshold as the condition under which a device may be labelled sterile.^[10]

Reaching that probability is a matter of logarithmic reduction. Microbial killing by heat or radiation follows first-order kinetics, meaning a fixed dose or time kills a fixed fraction of whatever is present, not a fixed number. The time or dose that cuts the population to one-tenth — a one-log reduction — is called the D-value, and it depends on the organism and the conditions.^[10] Each further D-value removes another factor of ten. This is why the starting population matters: to drive a population down to a 10⁻⁶ probability of one survivor, a process starting from a higher bioburden has to deliver more log reductions than one starting from a lower bioburden. A product carrying more organisms, or more resistant ones, needs a longer or stronger cycle.

Two broad strategies follow from this. The overkill approach sterilises for substantially longer than is needed to kill the measured bioburden, buying a large safety margin and relying less on precise knowledge of the starting count; typical moist-heat cycles run for several minutes to half an hour at 121 to 134 °C.^[10] The bioburden-based approach sets the cycle against the actual measured population, which is how radiation sterilisation doses are established under the ISO 11137 series: the average bioburden is determined from production lots to ISO 11737-1, a verification dose is derived from that bioburden, and a dose-verification study confirms that the chosen dose achieves the required SAL before the minimum sterilising dose is set.^[16] In a bioburden-based process the count is not merely a quality record — it literally sets the dose, and it is re-checked on a routine audit schedule so that any drift upward in the population triggers a review before it can undermine the sterility assurance.

The standards: USP, European Pharmacopoeia and ISO

Bioburden testing is governed by two families of standards that grew up in different industries and have largely converged.

On the pharmaceutical side, the controlling texts are the harmonised microbial-examination chapters. USP General Chapter <61> covers microbial enumeration — the TAMC and TYMC counts — and <62> covers the tests for specified microorganisms; the acceptance criteria sit separately in <1111>.^[1][3][12] These chapters are harmonised through the Pharmacopeial Discussion Group with the European Pharmacopoeia, whose equivalents are chapters 2.6.12 (enumeration) and 2.6.13 (specified micro-organisms), and with the Japanese Pharmacopoeia. The harmonisation took effect in 2009, when the older single “Microbial Limit Tests” chapter was split and rewritten into the aligned <61> and <62> that are in use today, so that a count run to one pharmacopeia is recognised by the others.^[12][15]

On the device side, the controlling standard is ISO 11737-1, published in its current form as the 2018 edition and adopted in the United States as ANSI/AAMI/ISO 11737-1:2018, Sterilization of health care products — Microbiological methods — Part 1: Determination of a population of microorganisms on products.^[4] It was developed by ISO Technical Committee 198, with the United States participating through a technical advisory group administered by AAMI. The 2018 revision added guidance on the most-probable-number method, a table for choosing a recovery-efficiency approach, an explanation of the correction factor, and a sharper focus on risk-based methods compared with the 2006 edition.^[4] Its companion, ISO 11737-2, covers the tests of sterility used to validate and maintain a sterilisation process — the confirmatory step that comes after the bioburden count.^[4]

Bioburden, endotoxin and sterility compared

Three microbiological measurements are easy to confuse because they all concern contamination, but each answers a different question and none replaces another.

Bioburden is a count of living organisms, taken before sterilisation. It asks how many, and it is quantitative. Sterility testing asks are any present at all, taken after sterilisation, and it is qualitative — a pass/fail on growth in culture.^[14] The two are sequential: bioburden sizes the problem, the sterilisation step solves it, and the sterility test confirms the solution. Endotoxin testing measures something that is not alive at all — the lipopolysaccharide shed from Gram-negative cell walls — and it is covered in depth in Endotoxin Testing Explained. The crucial relationship is that endotoxin is heat-stable and survives the death of the bacteria that made it, so a sterilisation process that drives bioburden to a 10⁻⁶ SAL can still leave endotoxin behind; removing it is a separate task called depyrogenation.

Bioburden on a certificate of analysis

Where a bioburden figure appears on a research certificate of analysis, it belongs to the microbiological section rather than the chemistry, and it should be read as a count with its method attached. A meaningful entry names the method or standard used (for example a USP <61> microbial enumeration, or an ISO 11737-1 determination), gives the result as CFU per gram or per millilitre for the TAMC and the TYMC separately, and states the limit it was judged against. A bare “bioburden: pass” with no number and no method says very little, because the acceptance limit depends entirely on what the material is for.

It is worth being clear about what the figure does and does not reach. A bioburden count is a measurement of living microbial load, and it is silent on chemical identity and purity — the province of HPLC and mass spectrometry — and silent on endotoxin and on the net amount of actual compound present, which is the subject of What Is Net Peptide Content. A complete picture of a research material comes from reading the microbiological numbers alongside the chemical ones, each for what it is designed to establish. Patriot Labs tests every batch through an independent US laboratory and publishes the certificate of analysis on the product page.

What this guide does not establish

This guide is an educational account of what bioburden is and how it is measured. Several limits are worth stating plainly.

• It describes a test, not any specific product. Whether a given lot has been bioburden-tested, and what count it returned, is a property of that lot and its certificate of analysis, not something that can be inferred from a compound’s name or from this page.
• The limits cited are regulatory reference points. The USP <1111> acceptance criteria and the 10⁻⁶ sterility assurance level apply to pharmaceutical preparations and terminally sterilised medical devices under pharmacopoeial and ISO frameworks; research-grade laboratory chemicals carry no equivalent legal requirement, and the figures are given only to show how such numbers are set.^[3][9]
• Nothing here concerns use in a person or animal. Routes of administration are named only to explain why different acceptance limits exist; they are not statements about any research compound, and this guide does not describe how to use any product.
• Nothing here describes where any peptide is made. The microbiology of bioburden and the mechanics of the count are general; they are not a claim about the origin, process or contamination status of any specific material.

Frequently asked questions

What is bioburden testing?

Bioburden testing is the measurement of the number of viable microorganisms — bacteria, yeasts and moulds — living on or in a material before it is sterilised or released. The organisms are recovered from the sample, grown on nutrient media under defined conditions, and counted, with the result expressed in colony-forming units (CFU) per gram, per millilitre or per device. It is a quantitative count of living contamination, not a test of chemical identity or purity.

What does bioburden mean?

Bioburden is the population of viable microorganisms on or in a product, component, raw material or package. The word means a count of living, reproduction-capable organisms — it does not include viruses, prions or protozoa, it does not count dead cells, and it does not measure the molecules such as endotoxin that dead cells leave behind.

What is the difference between bioburden testing and sterility testing?

Bioburden testing is quantitative and is done before sterilisation: it counts how many organisms are present. Sterility testing is qualitative and is done after sterilisation: it checks whether any viable organism can be detected at all, and is read as pass or fail. Bioburden sizes the contamination so a sterilisation process can be designed for it; the sterility test confirms the result afterward.

What media and temperatures are used for bioburden testing?

The total aerobic microbial count (TAMC) is grown on soybean–casein digest agar, also called tryptic soy agar, at 30 to 35 °C for three to five days. The total yeast and mould count (TYMC) is grown on Sabouraud dextrose agar at 20 to 25 °C for five to seven days. Running the two counts on different media at different temperatures lets bacteria and fungi each be read without one overwhelming the other.

What is a colony-forming unit (CFU)?

A colony-forming unit is one unit — a single cell or a clump of cells that were attached to each other — that grows into one visible colony on an agar plate. Bioburden is reported in CFU per gram, per millilitre or per device. The term is used rather than “cells” because a clump that lands as a single spot grows into one colony and is counted once, so the count is of colonies, not of individual organisms.

What is recovery efficiency and the correction factor in bioburden testing?

Recovery efficiency is the fraction of the organisms on a sample that a recovery method actually gets onto the plate; no method recovers all of them. It is measured either by extracting the same sample repeatedly and comparing the first pass with the total, or by applying a known number of organisms and seeing how many come back. The correction factor is the reciprocal of the recovery efficiency: a recovery efficiency of 0.5 gives a correction factor of 2, which is multiplied into the raw count to estimate the true population.

Why does sterilization validation need a bioburden count?

Because sterilisation kills a fixed fraction of the organisms present with each increment of dose or time, not a fixed number, the starting population determines how much treatment is needed to reach a given sterility assurance level. A bioburden count tells the process how many organisms it must reduce, which is why bioburden-based sterilisation — including radiation dose-setting under ISO 11137 — derives its dose from the measured count and re-audits it over time.

References

1. United States Pharmacopeia. General Chapter <61> Microbiological Examination of Nonsterile Products: Microbial Enumeration Tests, USP–NF. https://www.uspnf.com/sites/default/files/usp_pdf/EN/USPNF/generalChapter61.pdf
2. United States Pharmacopeia. General Chapter <62> Microbiological Examination of Nonsterile Products: Tests for Specified Microorganisms, USP–NF.
3. United States Pharmacopeia. General Chapter <1111> Microbiological Examination of Nonsterile Products: Acceptance Criteria for Pharmaceutical Preparations and Substances for Pharmaceutical Use, USP 32–NF 27 (official May 1, 2009). (Reference text reproduced at drugfuture.com.) https://www.drugfuture.com/pharmacopoeia/usp32/pub/data/v32270/usp32nf27s0_c1111h.html
4. ANSI/AAMI/ISO 11737-1:2018. Sterilization of health care products — Microbiological methods — Part 1: Determination of a population of microorganisms on products. (Overview via the ANSI Blog.) https://blog.ansi.org/ansi/ansi-aami-iso-11737-1-2018-sterilization/
5. ANSI/AAMI/ISO 11737-2:2009 (R2014). Sterilization of medical devices — Microbiological methods — Part 2: Tests of sterility performed in the definition, validation and maintenance of a sterilization process.
6. ISO 11137 series. Sterilization of health care products — Radiation (bioburden-based dose setting). International Organization for Standardization.
7. European Pharmacopoeia. Chapters 2.6.12 (Microbiological examination of non-sterile products: microbial enumeration tests) and 2.6.13 (…: test for specified micro-organisms). EDQM; harmonised through the Pharmacopeial Discussion Group.
8. Wikipedia contributors. Bioburden (definition; 21 CFR 211.110(a)(6); 21 CFR Title 21; membrane filtration at 0.45 µm; soybean–casein digest agar). https://en.wikipedia.org/wiki/Bioburden
9. Wikipedia contributors. Sterility assurance level (SAL as probability of a non-sterile unit; the 10⁻⁶ convention; log reduction). https://en.wikipedia.org/wiki/Sterility_assurance_level
10. Wikipedia contributors. Sterilization (microbiology) (overkill vs bioburden-based cycles; D-value and first-order kinetics; EN 556; steam cycle ranges). https://en.wikipedia.org/wiki/Sterilization_(microbiology)
11. Shrestha, A. Bioburden Testing: Definition, Procedure, USP Limits, and Medical Device Standards. Microbe Online (technical reference; recovery methods, correction factor). https://microbeonline.com/bioburden-testing-purpose-procedure-and-accepted-level/
12. GuideGxP. USP <61> vs <62>: Microbial Limit Tests (media, incubation temperatures and durations; factor-of-two recovery criterion; suitability strains). https://www.guidegxp.com/blogs/usp-guidelines/usp-61-vs-62
13. Microchem Laboratory. USP Microbial Enumeration Test (<61>) (method suitability run once per product lifetime; challenge organisms). https://microchemlab.com/test/usp-microbial-enumeration-test/
14. Pharmaceutical Microbiology. What Is Bioburden Testing? A Complete Guide (TVC; CFU calculation example; incubation 30–35 °C and 20–25 °C; standards referenced). https://www.pharmaceuticalmicrobiology.in/2025/10/what-is-bioburden-testing-complete.html
15. Pharma Manufacturing. USP Updates <61> and <62> for Microbial Testing of Non-Steriles (2009 harmonisation). https://www.pharmamanufacturing.com/articles/2009/060/
16. MedDeviceGuide. Bioburden Testing for Medical Devices: Complete ISO 11737-1 Guide (recovery-efficiency worked example; correction factor; SIP factor; ISO 11137 dose-setting steps). https://meddeviceguide.com/blog/bioburden-testing-medical-devices-guide
17. U.S. Code of Federal Regulations. 21 CFR 211.110(a)(6) — in-process control procedures including bioburden testing during manufacture.

For the other numbers on a research report, see Endotoxin Testing Explained, Understanding Peptide COA Testing and Peptide Impurities Explained; for the two analytical methods behind purity and identity, see What Is HPLC and What Is Mass Spectrometry.

All Patriot Labs products are sold strictly for in-vitro research and laboratory use only. Not for human or veterinary consumption. This guide is educational and describes the microbiology of bioburden and the methods used to count it in general terms; it is not medical advice, does not describe how to use any product, and makes no claim about the bioburden, purity or manufacturing location of any specific product.