{"id":3023,"date":"2026-10-03T16:06:23","date_gmt":"2026-10-03T16:06:23","guid":{"rendered":"https:\/\/nhdbio.com\/?p=3023"},"modified":"2026-10-15T03:53:50","modified_gmt":"2026-10-15T03:53:50","slug":"pool-de-peptides-a-masse-egale-versus-quantites-molaires-egales","status":"publish","type":"post","link":"https:\/\/nhdbio.com\/fr\/peptide-pool-equal-mass-versus-equal-molar-amounts\/","title":{"rendered":"M\u00e9langes de peptides : une masse \u00e9gale n\u2019est pas une quantit\u00e9 molaire \u00e9gale"},"content":{"rendered":"

\u201cMix equal amounts of each peptide\u201d sounds clear until someone asks what \u201camount\u201d means. Equal milligrams and equal micromoles can produce different mixtures. Decide which comparison the study needs before asking a supplier to prepare a pool.<\/p>\n

Mass counts weight; moles count molecular entities<\/h2>\n

A mole is the SI unit for amount of substance. Different molecules can have different molar masses, so the same weight does not necessarily contain the same number of molecules. The BIPM unit definition provides the basis for this distinction. [1]<\/p>\n

An equal-mass example<\/h2>\n

Imagine peptide A has a molar mass of 1,000 g\/mol and peptide B has a molar mass of 2,000 g\/mol. Assume the weighed quantities represent the defined pure peptides. One milligram of A is 1 micromole; one milligram of B is 0.5 micromole. Mixing those equal masses gives a 2:1 molar ratio of A to B. These are invented numbers, not product specifications.<\/p>\n

An equal-molar version of that mixture<\/h2>\n

To use 1 micromole of each, the calculated quantities are 1 mg of A and 2 mg of B. The total is 3 mg, with a 1:1 molar ratio. Neither design is automatically better. One controls the mass contribution; the other controls the specified molecular amount. The experiment determines which is useful.<\/p>\n

Powder composition affects the calculation<\/h2>\n

Real supplied powders can contain water, counterions or other components. A molar pool specification needs an appropriate peptide-quantity basis, not an assumed conversion from an HPLC area percentage. Ask how component quantities are assigned and which records support them. If the basis is uncertain, keep that uncertainty visible.<\/p>\n

Write the mixing rule into the order<\/h2>\n

List each sequence and final molecular form, then specify the quantity per component and whether the ratio is by mass or moles. Include the requested total quantity and delivery format. NHD\u2019s enquiry form lets you submit this component list for assessment; any pooling and quantity-verification work must be agreed separately.<\/p>\n

Useful links<\/h2>\n