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Is the pH value of XF assay media important to XF assays?

Yes!  It is important to have consistent and correct pH for each XF assay medium (pH 7.4 at 37°C).  Seahorse XF assays measure changes in metabolic analytes (i.e. oxygen and protons) to determine oxygen consumption rates (OCR) and extracellular acidification rates (ECAR) associated with cellular metabolic activities.  These analytes can be affected by the pH value of the assay media, therefore it is important to ensure that the assay media have consistent pH value.  Additionally, most cultured cells are acclimatized to a neutral pH environment- large changes to their pH environment can affect their metabolic profile/ phenotype.  Seahorse now offers XF base media with pH 7.4 at 37°C.  These media can be used without the need to adjust pH when used with XF supplements at recommended concentrations.  For more information, please check the Seahorse XF media selection guide.