How to Read Tesofensine COA — Lab Verification Made Simple

That Certificate of Analysis sitting in your inbox isn't just paperwork. It's the only verifiable proof that the peptide you received matches what you ordered. Miss one number in the wrong column and you're working with a compound that could be 15% impure without you knowing it. Our team has worked with hundreds of researchers who assumed their supplier's COA was accurate. Until they cross-referenced the data and found molecular weight discrepancies that made the entire batch unusable.

How do you read tesofensine COA to verify purity and quality?

To read tesofensine COA accurately, locate the purity percentage (target ≥98%), confirm the molecular weight matches 274.35 g/mol, verify HPLC retention time consistency, and check the test date is within 90 days. These four data points confirm molecular identity and manufacturing quality before use in any research protocol.

Most researchers stop at the purity number and assume they're done. That's insufficient. A COA with 99.2% purity means nothing if the molecular weight is off by 3 daltons or the HPLC chromatogram shows multiple unidentified peaks at retention times that shouldn't exist. This article covers how to read tesofensine COA line-by-line, which values matter most for research integrity, and what red flags disqualify a batch regardless of headline purity claims.

Step 1: Verify the Batch Number and Test Date on the COA

Every tesofensine COA must include a unique batch number and a specific test completion date. Cross-reference the batch number on the COA against the label on your vial. If they don't match exactly, the document doesn't correspond to the compound you received. This isn't paranoia: batch mix-ups occur in every manufacturing environment, and using data from the wrong batch means you're operating on false assumptions about what's in your container.

The test date tells you how recent the analysis is. Peptides degrade over time even when stored correctly, and a COA from 18 months ago no longer reflects the current state of the compound. We require test dates within 90 days of shipment for all Real peptides. Anything older raises questions about storage conditions between testing and delivery.

Batch traceability is the foundation of reproducible research. If you can't trace your compound to a specific synthesis run with date-stamped analytical data, you're introducing an uncontrolled variable into every experiment. Real Peptides issues batch-specific COAs with HPLC and mass spectrometry data for every peptide we ship. No generic documents, no recycled test results from prior batches.

Step 2: Interpret the Purity Percentage and HPLC Chromatogram

The purity percentage. Typically reported as ≥98% or ≥99%. Represents the proportion of tesofensine relative to all other compounds detected in the sample. This number comes from High-Performance Liquid Chromatography (HPLC), which separates molecules by retention time and quantifies each peak as a percentage of total area under the curve. A purity of 98.7% means tesofensine accounts for 98.7% of detected material; the remaining 1.3% is impurities, excipients, or degradation products.

What the purity number doesn't tell you: what those impurities are. A batch could be 99% pure but contain a structurally similar analogue that mimics tesofensine in HPLC but behaves differently in biological assays. This is why you must review the actual chromatogram, not just the summary value. The chromatogram should show one dominant peak at the expected retention time for tesofensine (typically 8–12 minutes depending on column and mobile phase) with minimal secondary peaks. Multiple peaks of similar height indicate incomplete synthesis or degradation.

Our manufacturing process targets ≥98% purity across all peptides, and we reject batches below this threshold before shipping. If you're working with tesofensine below 95% purity, you're introducing enough variability to compromise dose-response reliability in any protocol. The difference between 98% and 92% purity isn't trivial. It's the difference between reproducible data and noise.

Step 3: Confirm Molecular Weight Using Mass Spectrometry Data

Molecular weight confirmation via mass spectrometry (MS) is the definitive proof you received tesofensine and not a structurally similar compound. Tesofensine has a molecular weight of 274.35 g/mol. The MS data on your COA should show a peak at m/z 274 or 275 (depending on ionization method). If the reported molecular weight deviates by more than 1 dalton, the compound is not tesofensine.

Mass spectrometry works by ionizing the sample and measuring the mass-to-charge ratio of resulting ions. The spectrum shows peaks corresponding to molecular fragments and the intact molecular ion. For tesofensine, you're looking for the [M+H]+ ion at 275.35 m/z (protonated form) in positive ion mode. Secondary peaks should correspond to predictable fragments. Anything unidentified or at unexpected masses suggests contamination or synthesis errors.

We've encountered COAs where suppliers list "molecular weight confirmed" without providing the actual spectrum. That's insufficient. You need to see the raw MS data showing the base peak at the correct m/z value. At Real Peptides, every tesofensine batch includes full mass spectrometry data in the COA. Not a summary statement, but the actual spectrum with labeled peaks.

How to Read Tesofensine COA: Method and Standard Comparison

Key Takeaways

• To read tesofensine COA accurately, verify the batch number matches your vial label and confirm the test date is within 90 days of receipt. Older data no longer reflects the compound's current state.
• HPLC purity ≥98% is the baseline for research-grade tesofensine, but you must review the actual chromatogram to identify secondary peaks that indicate impurities or degradation products.
• Mass spectrometry data confirming molecular weight of 274.35 g/mol (±1 Da) is the definitive proof you received tesofensine. Without this, you cannot verify molecular identity.
• Water content above 5% and peptide content below 95% both reduce the effective dose per milligram, requiring recalculation of all protocol concentrations to maintain accuracy.
• Retention time consistency across batches using the same HPLC method indicates stable synthesis conditions. Variability suggests process control issues at the supplier level.

What If: Tesofensine COA Scenarios

What If the Purity Is Listed as 97.3% Instead of ≥98%?

Use it only if your protocol tolerates ±2% variability in active compound concentration. Purity below 98% increases the proportion of unidentified impurities, which may interfere with assay readouts or introduce off-target effects in biological systems. If you're running dose-response curves or mechanistic studies where precision matters, request a replacement batch. 97.3% purity is outside the standard research-grade specification and compromises reproducibility.

What If the Molecular Weight Shows 276.4 g/mol Instead of 274.35?

Do not use the compound. A 2-dalton deviation indicates either a synthesis error (wrong precursor incorporated), a salt form not disclosed on the label (unlikely for tesofensine), or contamination with a structurally similar analogue. Mass spectrometry is the gold standard for molecular identity. If the m/z value doesn't match the expected formula, you cannot assume the compound behaves as tesofensine in your assays.

What If the COA Shows Multiple HPLC Peaks Above 1% Each?

Investigate the retention times and relative intensities of secondary peaks. Peaks eluting before the main tesofensine peak typically represent synthesis intermediates or truncated fragments; peaks eluting after suggest oxidation products or polymerized forms. If any secondary peak exceeds 1.5% of total area, the batch purity is effectively below specification. Contact the supplier for identification of the impurity. Uncharacterized secondary peaks are unacceptable in research-grade material.

The Unfiltered Truth About Tesofensine COA Documents

Here's the honest answer: most researchers don't read tesofensine COA documents beyond the purity headline. That's a mistake. The purity percentage is a summary statistic. It doesn't tell you what the remaining 1–2% consists of, and it doesn't verify molecular identity. We've reviewed COAs from competitors where the purity was listed as 99.1% but the mass spectrometry data was missing entirely, the chromatogram showed unresolved peaks, and the test date was 14 months old. Those documents look professional, but they don't prove anything.

A legitimate COA includes raw analytical data: the full HPLC chromatogram with labeled peaks, the mass spectrum showing the molecular ion at the correct m/z value, and the sterility test results with organism identification method. If your supplier provides a single-page summary with no supporting data, you're trusting their word without verification. That's not how science works.

At Real Peptides, every batch ships with complete analytical documentation. HPLC traces, MS spectra, Karl Fischer water content, and peptide content by amino acid analysis. We don't summarize the data; we show you the data. That's the standard for research-grade peptides, and anything less introduces uncontrolled variables into your work.

The gap between headline purity and actual compound quality is where most peptide suppliers cut corners. You can't catch it unless you know how to read tesofensine COA documents line-by-line. If the molecular weight is wrong or the chromatogram shows multiple unidentified peaks, the batch is unusable regardless of what the purity summary claims. Cross-check every value before opening the vial. Once you reconstitute the peptide, you can't return it.