Die Elektrodialyse als Methode der Trennung und Bestimmung von Basen in biologischen Flüssigkeiten. I. Elektrodialyse wäßriger Lösungen von Carnosin, Kreatin und Kreatinin.
I. A modified Pauli app. is used with 3 types of membranes: at 120 v., current sometimes exceeds 20 milliamp. At pH 2.0-4.4 all 3 substances migrate to the cathode, carnosine (I) with the greatest velocity, creatine (II) the least; H2O transport to the side cells is relatively rapid. At pH 10-12 migration is prevented for I, slowed for II and creatinine (III). In aq. soln., II and III migrate much more slowly than I. Acid electrodialysis may serve to sep. I, II and III from colloids.[long dash]II. Lake 2 cc. of blood or fully-packed erythrocytes in 16 cc. H2O, deproteinize with 2 cc. of 25% base-free trichlor-acetic acid, put 5 cc. of filtrate in the middle cell of the Pauli app., H2O in the side cells. For serum or plasma, dilute 1 or 2 cc. 5 or 10 times without depro-teinization. After electrodialysis (120 v.) dil. the cathode soln. to 50 cc, heat 10-15 cc. aliquots 10-15 min. on a water bath with 5 cc. of 0.01 N H2SO4, cool, add 1 cc. 1.5% KIO3 and 50 mgm. KI, mix. After 15 min. titrate the I with 0.01 N Na2S2O3 standardized against the H2SO4. 2% accuracy is claimed if certain precautions are taken: CCl3CO2H concn. must not exceed 2.5-3%; during dialysis the anode acid is removed repeatedly and replaced with water; electrolyte-free water is used throughout; current is reg. by a rheostat below 20 milliamp.