The search bar on top is very effective in searching for compounds by name or CAS number. But please note that most of the stable labeled reference standards were custom-synthesized and may not have a CAS number.

This web catalog is not set up for online purchases. In order to place order for a reference standard, please either use the contact us form, quote request form, email (, or call (512-686-4444).

We now have a number of reference standards available as solution in flame sealed vials. The potency for each was independently confirmed using 500 MHz quantitative proton NMR (Q-NMR) analysis - this technique detects and determines concentration (in mg/mL) of the active component in the solution in a completely independent and accurate process.  This is so because the detector response (NMR integral intensity) is identical whether it be a major component or an impurity.  Most other analytical techniques suffer from a major problem that detection response for distinct molecules can be different.  Hence, we claim that our analytical reference standard solutions have the most accurate potency values and will provide more accurate values in your assays compared to when our competitor reference solutions are used.  We have put in significant effort in minimizing error in our custom Q-NMR methods.  The largest error was from weighing uncertainty, which has been significantly minimized by environmental controls and use of average from three weighings.  Long NMR recycle delays are used to ensure complete recovery of magnetization between subsequently scans and significant effort has been devoted to ensure narrow and symmetric line shapes than enable accurate determination of integral values.

Distributors of Chemtos Products include:


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