Dialyzers INDEX

One widely used performance index of hemodialyzers is that of clearance, defined similarly to that of the human kidney. The clearance of a hemodialyzer is the conceptual volume of blood (cm inin ) from which a uremic substance is completely removed by hemodialysis. Let Qg (cm min ) be the blood flow rate through the dialyzer, Qjj fern min ) the dialysate flow rate, and Cg and Cj3 (mgem ) the concentrations of a uremic substance in the blood and the dialysate, respectively, with the subscripts i and o indicating values at the inlet and outlet, respectively. The rate of transfer of the substance in the dialyzer w (mgmin ) is then given as... 

As in Equation 14 for the density increment, the right side of Equation 13a is equal to (dn/dg2)T,m,ns, i-e., the refractive index increment measured by using a dialyzed macromolecule solution and the dialyzate as reference solvent.)... 

Fluorescence detection at 284/310 nm (extinction/ emission wavelengths) leads to a detection limit of 1.3 mmol/L (0.14 mg/mL for / -cresol). Identification of phenol and /7-cresol may be confirmed by liquid chroma- tography/mass spectrometry. Because HPLC methods require only simple extraction, e.g., by ethyl acetate, and do not require further steps such as derivatization, they j are simple and rapid compared with gas chromatography or gas chromatography/mass spectrometry. Such methods I are useful for monitoring serum phenols in dialyzed patients as an index of hemodialysis adequacy. How- ever, the separation of the three isomers of cresol can only be performed by adding 3-cyclodextrin to the c liquid phase. q... 

Figure 3. Patient monitoring system. This apparatus was assembled only to determine the dialyzer UF index, L,. Knowing Lp then allows safe high-flux dialysis without specialized equipment...

Refractive Index Increment. The refractive index increment Sn/ C2 of the polymer (component 2) in the solution was measured with both single and two-component solvents. With the latter, the increment was determined both with solutions at constant solvent composition and with solutions dialyzed to osmotic equilibrium of the low molecular weight solvents to obtain (Sn/ac2) i, respectively. 

The mucin solutions were dialyzed against the solvent for one week at 5 after which the refractive index increment at constant chemical potential of solvent, (dn/dc)ii3, was determined using a differential refractometer model RF-600 from C. N. Wood M.F.G. Co. Newtown, Pa. Concentrations were also checked by this method assuming An = (dn/dc)M3AC. 

The aqueous phase was concentrated under nitrogen and dialyzed overnight at 4 . The contents of the dialysis tubing were analyzed for the components of gangliosides. Using the loss of the ganglioside components, (after dialysis) as an index of activity e.g. N-acetyl-neuraminic acid, hexoses, and N-acetylgalactosamine, it was observed that hydrolytic activity occurred only in anaerobic systems. 

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