“…section II.3) and apply also to Ca 2+ measurements. ,,,,,− Furthermore, binding of Ca 2+ to heparin may cause erroneous Ca 2+ determinations. , Special care must also be taken to prevent loss of CO 2 from the sample because the amount of Ca 2+ bound to proteins is very large, , and the concentration of free Ca 2+ depends even more strongly on the pH than in the case of Mg 2+ . , Moreover, a temperature dependence of the free calcium concentration was reported . Contrary to theoretical expectations, acetate interference was reported to increase with the concentration of lipophilic anionic sites in ETH 1001 ( Ca 2+ -5 ) membranes . In addition to reasons discussed above for a similar case of K + solid-contact electrodes by the same authors, doubts on this interpretation arise from the fact that high acetate concentrations strongly affect the responses of nearly all the Ca 2+ sensors tested in that particular investigation.…”