--- title: "Characterisation Standards: What Counts as Proof of a New Compound" description: "Reporting a new compound carries an evidential standard that the field agrees on: spectra that fit, a formula confirmed by mass or elemental analysis, and purity shown rather than asserted. Falling sh" canonical: https://lightmysky.com/learn/science/characterisation-standards-what-counts-as-proof-of-a-new-compound-mt_WKhYUq-eyd source: https://lightmysky.com/learn/science/characterisation-standards-what-counts-as-proof-of-a-new-compound-mt_WKhYUq-eyd.md retrieved: 2026-11-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Characterisation Standards: What Counts as Proof of a New Compound Reporting a new compound carries an evidential standard that the field agrees on: spectra that fit, a formula confirmed by mass or elemental analysis, and purity shown rather than asserted. Falling short of it is what makes results hard to repeat. Subject: Science · Area: Chemistry · Ages 22 to 24 Page: https://lightmysky.com/learn/science/characterisation-standards-what-counts-as-proof-of-a-new-compound-mt_WKhYUq-eyd ## Ready when they can - Lists the data a new compound needs and says what each item rules out - Judges a purity claim against the method used to support it - Explains why an isolated yield reported without characterisation is not a result - Writes a procedure at the level of detail another group would need to repeat it ## Lesson: Proof a compound is real A new compound needs a standard set of evidence, and each item rules something out. Fully assigned proton and carbon NMR spectra fix how the atoms connect and rule out a structural isomer; mirror-image forms need a chiral method. An exact mass or an elemental analysis confirms the formula and rules out a different composition. A purity measure matched to the claim, such as elemental analysis or chromatography, rules out a mixture. Formula mass is the bridge between the balance and the identity. Add the atomic masses in your formula, then predict what percent of the mass each element should supply. A match with elemental analysis supports the formula, and the molecular ion peak should land where the formula says. A mismatch flags impurity or a wrong formula. **Example.** Purity is shown, never just asserted. Match the method to the claim, and treat a lone yield number with no spectra as no result at all. If the formula does not match the measured composition, the identity claim is already in trouble. Write the method so another trained group can repeat it: grades, ratios, volumes, fractions. Saying purify the product is not repeatable, while naming the column, the 3 to 1 eluent mix, and the 10 mL fractions is. Keep a dated notebook of what you did, measured, and broke, plus a written method others can follow. **Recap.** Ratio, mass match, shown purity, and a method strangers can repeat: that is the standard. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Searching the Chemical Literature by Structure and by Reaction](https://lightmysky.com/learn/science/searching-the-chemical-literature-by-structure-and-by-reaction-mt_7vkNiUQ2uw) ## Optional connections - [Accurate Mass and Isotope Patterns as Formula Evidence](https://lightmysky.com/learn/science/accurate-mass-and-isotope-patterns-as-formula-evidence-mt_68vjdAPNrc) - [Two-Dimensional NMR and Assigning a Whole Structure](https://lightmysky.com/learn/science/two-dimensional-nmr-and-assigning-a-whole-structure-mt_UEC4dilKT9) ## Opens up - [Risk Assessment for a Reaction Nobody Has Run Here](https://lightmysky.com/learn/science/risk-assessment-for-a-reaction-nobody-has-run-here-mt_CdotJQjdka)