Problems of comparing blood glucose
molality and molarity determined with an Omni, an EML 105 and an Ebio analyser.
The graphical representation of variations of refractive indices as a function of molality at different temperatures is shown in the Figure 5.
Molar refractivity of citric acid in water increases with increase in the molality of solution and decreases with an increase in the temperature.
at values of m sufficiently low to be useful in determining the standard potential by extrapolation to zero molality have been made by a number of investigators (2 to 16].
Figure 2 is a plot of E[degrees]" at 0[degrees], 25[degrees], 60[degrees], and 90[degrees] C (open circles) as a function of molality. The closed circles were computed from the data of Harned and Ehlers [9] by the method described above.
where [m.sub.c] is cation molality, [m.sub.a] is anion molality, and [[lambda].sub.i-c], [[lambda].sub.i-a], and [[zeta].sub.i-a-c] are parameters that are functions of temperature and pressure.
Figure 5 shows the molality of carbon (including HC[O.sub.3.sup.-], C[O.sub.2], CaHC[O.sub.3.sup.+], CaC[O.sub.3], C[O.sub.3.sup.2-], MgHC[O.sub.3.sup.-], and MgC[O.sub.3]) dissolved in aqueous phase with different depths, gas compositions, and salinities.
The new generation of direct-reading glucose sensors responds to the molality of glucose, which is identical in whole blood and plasma, whereas the glucose concentrations in these two systems are different.
For example, some blood gas/electrolyte/metabolite instruments with direct-reading glucose biosensors are calibrated with aqueous calibrators to provide results according to the "relative molality" of glucose in the sample.
The
molality of glucose (i.e., amount of glucose per unit water mass) in whole blood and plasma is identical.
The new generation of direct-reading glucose sensors detect the molality of glucose [4].
The molality results from the direct-reading sensor can be multiplied by a factor derived from the ratio of the water concentrations of calibrator and sample to yield the true glucose concentration.