On the absorption capacity of the REDY cartridge.

The absorption capacity of the REDY cartridge was investigated exclusively by in vitro experiments. The maximum absorption capacity for urea, phosphate, creatinine, and urinc acid, was found to be respectively 55 g, more than 4 g (phosphorus), 10 g, and more than 7,5 g. The maximum absorption rates of the same substances were found to be 600-800 mg/min., more than 33 mg/min., more than 170 mg/min., and 13 mg/min. respectively. The ability of the cartridge to absorb urea was found to be practically unaffected by 2 mmol of copper and 7 mmol of zinc, and to be unaffected by supraphysiological concentrations of lithium. The amount of exchangeable cations was determined for three cartridges, and found to be 6100, 3800, and 7200 mmol. The cation exchanger was found to act as a buffer, giving the whole cartridge a buffering capacity of 0,6 mol. Of the layers of cation exchanger, anion exchanger, and activated charcoal, only the latter was found to be able to bind urea.