Analytical Testing & Quality

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Analytical Testing & Quality

How research peptide identity and purity are verified, and how to read the supporting analytical documentation.

Circular Dichroism and Peptide Secondary Structure

What a far-ultraviolet circular dichroism spectrum reports, the helix, sheet and disordered signatures, and why most short peptides give a disordered result.

5 min read

Analytical Testing & Quality

Detecting What Does Not Absorb: ELSD and CAD

When a UV detector shows a flat line, the analyte is still there. Two detectors that respond to mass instead, and what their non-linear response does to a purity figure.

4 min read

Analytical Testing & Quality

What Happens Between the Vial and the Autosampler

Dissolution solvent, injection solvent mismatch, adsorption, filtration and hours in the autosampler. Everything that changes a chromatogram before the column sees it.

4 min read

Analytical Testing & Quality

TFA or Formic Acid: Which One Costs You the Chromatogram

The acid in the mobile phase decides whether you get peak shape or mass spectrometer sensitivity. You rarely get both, and certificates rarely say which was chosen.

4 min read

Analytical Testing & Quality

Retention Time Is Evidence, but Only Against a Standard

It is not a property of the molecule. It is a property of the molecule on one system, that day. What it establishes, what it cannot, and why relative retention travels better.

4 min read

Analytical Testing & Quality

Deconvolution: Why the Mass on a Certificate Was Calculated, Not Measured

Electrospray gives a charge envelope, not a mass. How the software works backwards to a neutral mass, and the four ways that calculation goes wrong.

4 min read

Analytical Testing & Quality

Why Two Peptides at 98 Percent Are Not Equally Pure

Area percentage assumes every molecule absorbs the same. None of them do. What that means for truncated impurities, blends and comparing figures between compounds.

4 min read

Analytical Testing & Quality

CJC-1295 Without DAC and Ipamorelin in One Vial

A 29-residue peptide and a 5-residue one, five to one by mass. Why ipamorelin lands between two of the larger peptide charge states, and how isotope spacing tells them apart.

4 min read

Analytical Testing & Quality

BPC-157 and TB-500 in One Vial: 530 Daltons Apart

Two peptides about as analytically distinct as a pair in one vial can be. What the total on the label means, and why the peak areas will not give you the mass ratio.

3 min read

Analytical Testing & Quality

Why BPC-157 Peaks Broaden: Three Prolines in a Row

Proline is the only residue whose preceding bond adopts cis and trans in comparable proportions. Three consecutive ones is why a BPC-157 chromatogram looks the way it does.

4 min read

Analytical Testing & Quality

5-Amino-1MQ: A Permanent Cation, Not a Peptide

A quaternary nitrogen means a charge no pH removes. Why the mass spectrum shows M+ rather than M+H, and why reading it the usual way gives a confidently wrong number.

4 min read

Analytical Testing & Quality

Long R3 IGF-1: Where Peptide Analysis Becomes Protein Analysis

Eighty-three residues, three disulfide bonds and fifteen possible cysteine pairings. Why intact mass is blind to the failure mode that matters most.

4 min read

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The products offered by ExoLabz are intended solely for research purposes. These products are not for human consumption, are not intended for medical use, and have not been approved by the FDA for any therapeutic or diagnostic purpose. ExoLabz makes no claims regarding the safety, efficacy, or intended use of these products outside of a controlled research environment. By purchasing our products, you agree to use them strictly for scientific research and in compliance with all local laws and regulations.

Research-Grade Peptides and Compounds, Shipped from the USA | For Research Use Only.

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