<prompt> The most impoant buffer in interstitial fluid:PhosphateBicarbonateHistidineProtein  <response>: The chemical buffer systems in the body - bicarbonate system, phosphate system, and the proteins. Bicarbonate buffer is quantitatively the most impoant buffer in ECF compament; it buffers non-carbonic acid. Hence, option B is correct. Intracellular proteins account for 70 of IC buffering . Phosphate helps in intracellular buffering . 