Research Use Only. The information on this page summarizes published peptide research for laboratory and educational reference. The compounds discussed are intended exclusively for in vitro and non-clinical research. Nothing on this page constitutes medical advice or describes human use, diagnosis, treatment, or therapeutic application.
Overview
High-performance liquid chromatography (HPLC) is the foundational analytical method for synthetic peptide quality control. Every credible research peptide preparation has been characterized by HPLC, and every Certificate of Analysis worth reading reports an HPLC purity figure with the underlying chromatogram. Understanding what HPLC actually measures, what it does not measure, and how to interpret the data on a COA is one of the most important pieces of methodology literacy for any researcher working with synthetic peptides.
This article covers the analytical chemistry behind HPLC peptide verification at the level of detail a researcher needs to evaluate supplier documentation, distinguish credible analytical reports from marketing material, and understand the limitations of any single analytical method. It is part of the methodology track on the GENEVIUM Research Methodology Hub, which covers analytical verification, preparation methodology, and laboratory workflow standards for research peptides.
What HPLC Measures
HPLC is a separation method first and an analytical method second. It separates the components of a complex chemical mixture by their differential interaction with a stationary phase under controlled solvent flow, then quantifies each component by its detection signal. For synthetic peptides, that means HPLC takes a peptide preparation, separates the target compound from byproducts, contaminants, and degradation products, and reports how much of each is present.
The Separation Principle
The chemistry of HPLC separation is straightforward. The peptide preparation is dissolved in a starting solvent and injected into a column packed with a porous stationary phase material. The mobile phase, a flowing solvent or solvent gradient, carries the peptide through the column. Components in the preparation interact with the stationary phase with different strengths and partition between the stationary and mobile phases at different rates. Components that interact weakly with the stationary phase pass through quickly. Components that interact strongly are retained longer.
The result is that components elute, or exit the column, at different times. A detector at the end of the column registers the moment each component passes by, producing a signal trace plotted against time. This trace is the chromatogram.
What the Chromatogram Shows
A clean synthetic peptide preparation produces a chromatogram with one large, sharp peak at the retention time of the target compound and minimal signal elsewhere. A contaminated or degraded preparation shows the target peak alongside additional peaks corresponding to truncated sequences, modified peptides, or degradation products. The number, position, and area of these additional peaks describe the impurity profile of the sample.
Three pieces of information come out of an HPLC analysis: the total number of detectable components in the sample, the relative quantity of each component (peak area as percentage of total), and the retention time of each component, used in combination with reference standards to assign identity. For research peptide verification, the key output is the percentage purity figure: the area under the target peak divided by the total area under all peaks, multiplied by 100.
Reverse-Phase HPLC for Peptides
Reverse-phase HPLC (RP-HPLC) is the standard variant used for synthetic peptide analysis. The stationary phase is hydrophobic, the mobile phase is polar, and peptides separate based on their hydrophobicity. Less hydrophobic peptides elute first; more hydrophobic peptides elute later.
Stationary Phase Chemistry
The stationary phase in RP-HPLC is silica beads coated with an alkyl chain. The most common chain lengths are C18 (octadecyl, 18 carbons) and C8 (octyl, 8 carbons). C18 columns retain peptides more strongly and provide better resolution for typical synthetic peptide mixtures. C4 columns retain peptides less strongly and are sometimes used for proteins or very hydrophobic peptides.
The pore size of the silica matters for peptide work. Standard 100 Å pore silica is appropriate for small peptides under approximately 30 residues. Larger peptides and small proteins require 300 Å pore silica to allow access to the interior of the bead, where the surface-area-to-volume ratio actually drives separation efficiency.
Mobile Phase Composition
The mobile phase for peptide RP-HPLC is typically a binary system: water with trifluoroacetic acid (TFA) as solvent A, and acetonitrile with TFA as solvent B. TFA at 0.1% concentration serves as an ion-pairing agent that masks peptide charge and improves peak shape. Without an ion-pairing agent, peptides produce broad, asymmetric peaks that compromise resolution and integration accuracy.
The peptide elutes when the solvent composition reaches a percentage of acetonitrile sufficient to disrupt the hydrophobic interaction between the peptide and the stationary phase. The relationship between elution time and acetonitrile percentage is the basis for retention-time identity confirmation across runs.
Gradient Elution
Synthetic peptide analysis uses gradient elution, in which the proportion of organic solvent (acetonitrile) increases over time. A typical analytical gradient runs from 5% acetonitrile to 60% acetonitrile over 20 to 40 minutes. The gradient is shallow enough to resolve closely related impurities but steep enough to keep run times manageable.
Isocratic elution, with constant solvent composition, is rarely used for synthetic peptide quality control because it cannot resolve mixtures of peptides with widely different hydrophobicities in a single run.
UV Detection at 214 nm
The detector at the end of the HPLC column registers the optical absorbance of the eluting solvent stream. For peptide work, ultraviolet (UV) detection at 214 nanometers is the standard.
Why 214 nm Rather Than 280 nm
Peptide bonds absorb UV light strongly at 214 nm. Every amino acid residue in every peptide contributes to absorbance at this wavelength because every residue contains a peptide bond. UV detection at 214 nm therefore captures all peptides in the sample, regardless of amino acid composition.
UV detection at 280 nm captures only peptides containing aromatic residues, primarily tryptophan and tyrosine, with a smaller contribution from phenylalanine. For peptides that lack aromatic residues, 280 nm detection misses them entirely. For peptides with aromatic residues, 280 nm captures the target peptide but cannot detect non-aromatic impurities.
The practical consequence is that purity figures reported from 280 nm detection can be artificially inflated. Non-aromatic byproducts in the preparation are invisible to 280 nm detection, so the integrated peak area of the target peptide appears to be a larger fraction of the total signal than it actually is. A research-grade COA should specify the detection wavelength used. 214 nm is the appropriate standard.
Reading the Detection Output
The chromatogram axes are time on the x-axis (in minutes, elapsed since sample injection) and detector signal on the y-axis (in milli-absorbance units, mAU, proportional to the concentration of UV-absorbing material in the eluting solvent stream). A chromatogram of a clean peptide preparation shows a flat baseline (no signal) for most of the run, with a sharp, narrow peak at the retention time of the target compound. Peak height is influenced by sample concentration; peak area is the integrated absorbance over the duration of the peak. Area, not height, is the basis for purity calculation.
Calculating Purity
The purity figure on a COA is calculated by integrating the area under each peak in the chromatogram and expressing the area of the target peak as a percentage of the total integrated area.
Peak Area Integration
Modern HPLC software automatically integrates peak areas using a baseline algorithm. The software identifies the start and end of each peak based on where the signal rises above and returns to a defined baseline threshold, and calculates the area under the curve between those points using trapezoidal numerical integration.
The integration parameters matter. A baseline threshold set too high misses small impurity peaks. A threshold set too low integrates noise as signal. Reproducible peak integration requires consistent parameters across runs and across batches. A research-grade COA should specify the integration software and parameters used, or include the chromatogram with peak area annotations visible.
The 99% Standard
Research-grade synthetic peptides are expected to achieve at least 99% purity by RP-HPLC at 214 nm. Material below this threshold contains more than 1% byproducts, which is sufficient to introduce measurable variability into receptor binding assays, dose-response measurements, and quantitative pharmacology work.
For applications requiring particularly clean signal, 99.5% or higher purity may be required. Quantitative structural biology, isothermal titration calorimetry, and surface plasmon resonance measurements are examples of techniques where impurity levels above 0.5% can affect results.
A purity figure reported without the underlying chromatogram is a marketing number, not analytical data. The chromatogram is what allows a researcher to verify that the integration was performed correctly, that the impurities are characterized, and that the figure is meaningful.
What HPLC Cannot Do Alone
HPLC measures chromatographic behavior. It does not measure molecular weight, sequence, or structure directly. A pure-looking HPLC trace, with a single sharp peak and no detectable byproducts, is necessary but not sufficient evidence that the labeled compound is what is in the vial.
Two failure modes are common. First, a peptide with a completely wrong sequence can produce a clean HPLC peak if the synthesis happened to produce a homogeneous wrong product. Second, peptides differing by a single amino acid can co-elute under standard gradient conditions, showing as a single peak even though the preparation is a mixture.
The standard solution is to pair HPLC with mass spectrometry. Mass spec confirms that the molecular weight of the eluted material matches the theoretical molecular weight calculated from the labeled sequence. The combination of HPLC purity and MS identity confirmation is the analytical baseline a research-grade COA should document. Methodology for evaluating a research peptide supplier in detail, including third-party verification standards, is covered in the Research Peptide Supplier Evaluation Criteria reference.
Reading an HPLC Chromatogram on a COA
A research-grade Certificate of Analysis includes the HPLC chromatogram alongside the reported purity figure. The reader should verify the following: the labeled axes show time and signal intensity correctly, the reported retention time of the target peak is reasonable for a peptide of the labeled sequence (typically between 5 and 30 minutes for analytical runs), the detection wavelength is specified (214 nm is the appropriate standard), the mobile phase gradient is described, the integration parameters are visible (peak area annotations), and the chromatogram is unique to the batch (matching the batch number on the COA).
A COA that displays the same chromatogram across multiple batches indicates that the supplier is reusing analytical data from one batch to certify others. A COA that displays only a numerical purity figure without the underlying chromatogram is incomplete documentation. The GENEVIUM COA Lookup page documents per-batch chromatograms retrievable by lot number for every research peptide in the catalog. Format and storage methodology for the lyophilized peptide preparations being analyzed is covered in the Lyophilized Peptide Methodology reference. For solution preparation following analytical verification, the calculator on the Research Hub determines the bacteriostatic water volume required to achieve a target concentration from the lyophilized starting material.
Third-Party HPLC Verification
In-house HPLC analysis is necessary but introduces a structural conflict of interest. The same operation that synthesizes and sells the peptide controls the analytical data that defines its quality. Third-party verification, in which an independent analytical chemistry laboratory performs the HPLC analysis, eliminates this conflict.
The independent laboratory should be operationally separate from the synthesis operation, accredited under recognized analytical standards, and using current-generation instrumentation. Researchers evaluating a supplier should ask whether the COAs displayed are produced in-house or by a third party, and should treat third-party verification as the higher-confidence standard.
For laboratory research applications, GENEVIUM research peptides ship with batch-specific Certificates of Analysis documenting third-party HPLC verification at 214 nm with full chromatograms, mass spectrometry confirmation, and 99%+ purity standards.
Frequently Asked Questions
What HPLC purity threshold is required for research-grade peptides?
The accepted minimum threshold for research-grade synthetic peptides is 99% purity by reverse-phase HPLC at 214 nm. Material below this threshold contains more than 1% byproducts, which is sufficient to introduce variability into receptor binding measurements and quantitative pharmacology work. For applications requiring particularly clean signal, such as quantitative structural biology, isothermal titration calorimetry, or surface plasmon resonance work, purity standards above 99.5% may be required. The purity figure on a COA is meaningful only when accompanied by the underlying chromatogram, the wavelength of detection, and the integration parameters used to calculate the value.
Why is 214 nm the standard detection wavelength for peptide HPLC?
Peptide bonds absorb UV light strongly at 214 nm, and every amino acid residue in every peptide contributes to absorbance at this wavelength. Detection at 214 nm therefore captures all peptides in the sample regardless of amino acid composition. Detection at 280 nm captures only peptides containing aromatic residues (tryptophan, tyrosine, phenylalanine), which means non-aromatic byproducts in a preparation are invisible to 280 nm detection. Purity figures reported from 280 nm detection can be artificially inflated for this reason.
Can HPLC alone confirm the identity of a synthetic peptide?
No. HPLC measures chromatographic behavior, not molecular weight or sequence. A peptide with the wrong sequence can produce a clean HPLC peak if the synthesis was homogeneous, and peptides differing by a single amino acid can co-elute as a single peak. The standard analytical approach pairs HPLC with mass spectrometry, where mass spec confirms that the molecular weight of the eluted material matches the theoretical molecular weight calculated from the labeled sequence.
What does third-party HPLC verification mean?
Third-party HPLC verification means the HPLC analysis was performed by an analytical chemistry laboratory operationally independent of the peptide synthesis operation. The independent laboratory uses its own instrumentation and reports the results without commercial incentive to overstate purity. In-house HPLC analysis carries a structural conflict of interest that third-party verification eliminates. A research-grade Certificate of Analysis should specify whether the analytical data is produced in-house or by a named third-party laboratory.
Are GENEVIUM research peptides intended for human use?
No. All GENEVIUM peptides are research-use-only compounds intended exclusively for laboratory research, in vitro work, and non-clinical investigation. They are not approved for, and are not to be used for, human consumption, therapeutic application, or any clinical purpose.
HPLC Peptide Verification: Methodology and Standards
HPLC Peptide Verification: Methodology and Standards
Overview
High-performance liquid chromatography (HPLC) is the foundational analytical method for synthetic peptide quality control. Every credible research peptide preparation has been characterized by HPLC, and every Certificate of Analysis worth reading reports an HPLC purity figure with the underlying chromatogram. Understanding what HPLC actually measures, what it does not measure, and how to interpret the data on a COA is one of the most important pieces of methodology literacy for any researcher working with synthetic peptides.
This article covers the analytical chemistry behind HPLC peptide verification at the level of detail a researcher needs to evaluate supplier documentation, distinguish credible analytical reports from marketing material, and understand the limitations of any single analytical method. It is part of the methodology track on the GENEVIUM Research Methodology Hub, which covers analytical verification, preparation methodology, and laboratory workflow standards for research peptides.
What HPLC Measures
HPLC is a separation method first and an analytical method second. It separates the components of a complex chemical mixture by their differential interaction with a stationary phase under controlled solvent flow, then quantifies each component by its detection signal. For synthetic peptides, that means HPLC takes a peptide preparation, separates the target compound from byproducts, contaminants, and degradation products, and reports how much of each is present.
The Separation Principle
The chemistry of HPLC separation is straightforward. The peptide preparation is dissolved in a starting solvent and injected into a column packed with a porous stationary phase material. The mobile phase, a flowing solvent or solvent gradient, carries the peptide through the column. Components in the preparation interact with the stationary phase with different strengths and partition between the stationary and mobile phases at different rates. Components that interact weakly with the stationary phase pass through quickly. Components that interact strongly are retained longer.
The result is that components elute, or exit the column, at different times. A detector at the end of the column registers the moment each component passes by, producing a signal trace plotted against time. This trace is the chromatogram.
What the Chromatogram Shows
A clean synthetic peptide preparation produces a chromatogram with one large, sharp peak at the retention time of the target compound and minimal signal elsewhere. A contaminated or degraded preparation shows the target peak alongside additional peaks corresponding to truncated sequences, modified peptides, or degradation products. The number, position, and area of these additional peaks describe the impurity profile of the sample.
Three pieces of information come out of an HPLC analysis: the total number of detectable components in the sample, the relative quantity of each component (peak area as percentage of total), and the retention time of each component, used in combination with reference standards to assign identity. For research peptide verification, the key output is the percentage purity figure: the area under the target peak divided by the total area under all peaks, multiplied by 100.
Reverse-Phase HPLC for Peptides
Reverse-phase HPLC (RP-HPLC) is the standard variant used for synthetic peptide analysis. The stationary phase is hydrophobic, the mobile phase is polar, and peptides separate based on their hydrophobicity. Less hydrophobic peptides elute first; more hydrophobic peptides elute later.
Stationary Phase Chemistry
The stationary phase in RP-HPLC is silica beads coated with an alkyl chain. The most common chain lengths are C18 (octadecyl, 18 carbons) and C8 (octyl, 8 carbons). C18 columns retain peptides more strongly and provide better resolution for typical synthetic peptide mixtures. C4 columns retain peptides less strongly and are sometimes used for proteins or very hydrophobic peptides.
The pore size of the silica matters for peptide work. Standard 100 Å pore silica is appropriate for small peptides under approximately 30 residues. Larger peptides and small proteins require 300 Å pore silica to allow access to the interior of the bead, where the surface-area-to-volume ratio actually drives separation efficiency.
Mobile Phase Composition
The mobile phase for peptide RP-HPLC is typically a binary system: water with trifluoroacetic acid (TFA) as solvent A, and acetonitrile with TFA as solvent B. TFA at 0.1% concentration serves as an ion-pairing agent that masks peptide charge and improves peak shape. Without an ion-pairing agent, peptides produce broad, asymmetric peaks that compromise resolution and integration accuracy.
The peptide elutes when the solvent composition reaches a percentage of acetonitrile sufficient to disrupt the hydrophobic interaction between the peptide and the stationary phase. The relationship between elution time and acetonitrile percentage is the basis for retention-time identity confirmation across runs.
Gradient Elution
Synthetic peptide analysis uses gradient elution, in which the proportion of organic solvent (acetonitrile) increases over time. A typical analytical gradient runs from 5% acetonitrile to 60% acetonitrile over 20 to 40 minutes. The gradient is shallow enough to resolve closely related impurities but steep enough to keep run times manageable.
Isocratic elution, with constant solvent composition, is rarely used for synthetic peptide quality control because it cannot resolve mixtures of peptides with widely different hydrophobicities in a single run.
UV Detection at 214 nm
The detector at the end of the HPLC column registers the optical absorbance of the eluting solvent stream. For peptide work, ultraviolet (UV) detection at 214 nanometers is the standard.
Why 214 nm Rather Than 280 nm
Peptide bonds absorb UV light strongly at 214 nm. Every amino acid residue in every peptide contributes to absorbance at this wavelength because every residue contains a peptide bond. UV detection at 214 nm therefore captures all peptides in the sample, regardless of amino acid composition.
UV detection at 280 nm captures only peptides containing aromatic residues, primarily tryptophan and tyrosine, with a smaller contribution from phenylalanine. For peptides that lack aromatic residues, 280 nm detection misses them entirely. For peptides with aromatic residues, 280 nm captures the target peptide but cannot detect non-aromatic impurities.
The practical consequence is that purity figures reported from 280 nm detection can be artificially inflated. Non-aromatic byproducts in the preparation are invisible to 280 nm detection, so the integrated peak area of the target peptide appears to be a larger fraction of the total signal than it actually is. A research-grade COA should specify the detection wavelength used. 214 nm is the appropriate standard.
Reading the Detection Output
The chromatogram axes are time on the x-axis (in minutes, elapsed since sample injection) and detector signal on the y-axis (in milli-absorbance units, mAU, proportional to the concentration of UV-absorbing material in the eluting solvent stream). A chromatogram of a clean peptide preparation shows a flat baseline (no signal) for most of the run, with a sharp, narrow peak at the retention time of the target compound. Peak height is influenced by sample concentration; peak area is the integrated absorbance over the duration of the peak. Area, not height, is the basis for purity calculation.
Calculating Purity
The purity figure on a COA is calculated by integrating the area under each peak in the chromatogram and expressing the area of the target peak as a percentage of the total integrated area.
Peak Area Integration
Modern HPLC software automatically integrates peak areas using a baseline algorithm. The software identifies the start and end of each peak based on where the signal rises above and returns to a defined baseline threshold, and calculates the area under the curve between those points using trapezoidal numerical integration.
The integration parameters matter. A baseline threshold set too high misses small impurity peaks. A threshold set too low integrates noise as signal. Reproducible peak integration requires consistent parameters across runs and across batches. A research-grade COA should specify the integration software and parameters used, or include the chromatogram with peak area annotations visible.
The 99% Standard
Research-grade synthetic peptides are expected to achieve at least 99% purity by RP-HPLC at 214 nm. Material below this threshold contains more than 1% byproducts, which is sufficient to introduce measurable variability into receptor binding assays, dose-response measurements, and quantitative pharmacology work.
For applications requiring particularly clean signal, 99.5% or higher purity may be required. Quantitative structural biology, isothermal titration calorimetry, and surface plasmon resonance measurements are examples of techniques where impurity levels above 0.5% can affect results.
A purity figure reported without the underlying chromatogram is a marketing number, not analytical data. The chromatogram is what allows a researcher to verify that the integration was performed correctly, that the impurities are characterized, and that the figure is meaningful.
What HPLC Cannot Do Alone
HPLC measures chromatographic behavior. It does not measure molecular weight, sequence, or structure directly. A pure-looking HPLC trace, with a single sharp peak and no detectable byproducts, is necessary but not sufficient evidence that the labeled compound is what is in the vial.
Two failure modes are common. First, a peptide with a completely wrong sequence can produce a clean HPLC peak if the synthesis happened to produce a homogeneous wrong product. Second, peptides differing by a single amino acid can co-elute under standard gradient conditions, showing as a single peak even though the preparation is a mixture.
The standard solution is to pair HPLC with mass spectrometry. Mass spec confirms that the molecular weight of the eluted material matches the theoretical molecular weight calculated from the labeled sequence. The combination of HPLC purity and MS identity confirmation is the analytical baseline a research-grade COA should document. Methodology for evaluating a research peptide supplier in detail, including third-party verification standards, is covered in the Research Peptide Supplier Evaluation Criteria reference.
Reading an HPLC Chromatogram on a COA
A research-grade Certificate of Analysis includes the HPLC chromatogram alongside the reported purity figure. The reader should verify the following: the labeled axes show time and signal intensity correctly, the reported retention time of the target peak is reasonable for a peptide of the labeled sequence (typically between 5 and 30 minutes for analytical runs), the detection wavelength is specified (214 nm is the appropriate standard), the mobile phase gradient is described, the integration parameters are visible (peak area annotations), and the chromatogram is unique to the batch (matching the batch number on the COA).
A COA that displays the same chromatogram across multiple batches indicates that the supplier is reusing analytical data from one batch to certify others. A COA that displays only a numerical purity figure without the underlying chromatogram is incomplete documentation. The GENEVIUM COA Lookup page documents per-batch chromatograms retrievable by lot number for every research peptide in the catalog. Format and storage methodology for the lyophilized peptide preparations being analyzed is covered in the Lyophilized Peptide Methodology reference. For solution preparation following analytical verification, the calculator on the Research Hub determines the bacteriostatic water volume required to achieve a target concentration from the lyophilized starting material.
Third-Party HPLC Verification
In-house HPLC analysis is necessary but introduces a structural conflict of interest. The same operation that synthesizes and sells the peptide controls the analytical data that defines its quality. Third-party verification, in which an independent analytical chemistry laboratory performs the HPLC analysis, eliminates this conflict.
The independent laboratory should be operationally separate from the synthesis operation, accredited under recognized analytical standards, and using current-generation instrumentation. Researchers evaluating a supplier should ask whether the COAs displayed are produced in-house or by a third party, and should treat third-party verification as the higher-confidence standard.
For laboratory research applications, GENEVIUM research peptides ship with batch-specific Certificates of Analysis documenting third-party HPLC verification at 214 nm with full chromatograms, mass spectrometry confirmation, and 99%+ purity standards.
Frequently Asked Questions
What HPLC purity threshold is required for research-grade peptides?
The accepted minimum threshold for research-grade synthetic peptides is 99% purity by reverse-phase HPLC at 214 nm. Material below this threshold contains more than 1% byproducts, which is sufficient to introduce variability into receptor binding measurements and quantitative pharmacology work. For applications requiring particularly clean signal, such as quantitative structural biology, isothermal titration calorimetry, or surface plasmon resonance work, purity standards above 99.5% may be required. The purity figure on a COA is meaningful only when accompanied by the underlying chromatogram, the wavelength of detection, and the integration parameters used to calculate the value.
Why is 214 nm the standard detection wavelength for peptide HPLC?
Peptide bonds absorb UV light strongly at 214 nm, and every amino acid residue in every peptide contributes to absorbance at this wavelength. Detection at 214 nm therefore captures all peptides in the sample regardless of amino acid composition. Detection at 280 nm captures only peptides containing aromatic residues (tryptophan, tyrosine, phenylalanine), which means non-aromatic byproducts in a preparation are invisible to 280 nm detection. Purity figures reported from 280 nm detection can be artificially inflated for this reason.
Can HPLC alone confirm the identity of a synthetic peptide?
No. HPLC measures chromatographic behavior, not molecular weight or sequence. A peptide with the wrong sequence can produce a clean HPLC peak if the synthesis was homogeneous, and peptides differing by a single amino acid can co-elute as a single peak. The standard analytical approach pairs HPLC with mass spectrometry, where mass spec confirms that the molecular weight of the eluted material matches the theoretical molecular weight calculated from the labeled sequence.
What does third-party HPLC verification mean?
Third-party HPLC verification means the HPLC analysis was performed by an analytical chemistry laboratory operationally independent of the peptide synthesis operation. The independent laboratory uses its own instrumentation and reports the results without commercial incentive to overstate purity. In-house HPLC analysis carries a structural conflict of interest that third-party verification eliminates. A research-grade Certificate of Analysis should specify whether the analytical data is produced in-house or by a named third-party laboratory.
Are GENEVIUM research peptides intended for human use?
No. All GENEVIUM peptides are research-use-only compounds intended exclusively for laboratory research, in vitro work, and non-clinical investigation. They are not approved for, and are not to be used for, human consumption, therapeutic application, or any clinical purpose.