An ion exchange reaction, comprising the step of treating at least one ionizable substance and an insoluble, open-chain high molecular-weight polymer containing ion exchange groups in a polyphase solvent medium comprising an aqueous phase and a water-immiscible phase to effect an interchange of ions. This insoluble ion exchanger may be amylose, amylopectin, inulins, alpha cellulose, oxycellulose, xylans, pectins, algins, glycogens, chitins, chondroitin sulphuric acid, heparin, hyaluronic acid, levans and dextrans. A preferred ion-exchanger can be derived from paper, cotton, wood pulp and cotton cloth and may be in the form of sheeting, belting, pressed solids or finely divided particles. These ion exchange groups may be either acidic (cation exchanger) e.g. a carboxyl group, or basic (anion exchanger), e.g. primary, secondary and tertiary amino groups or quaternary ammonium salts. The non-aqueous solvents may be methylethyl ketone, methylisobutyl ketone, diethyl ketone, methylamyl ketons, butanal, pentanal, hexanal, heptanal, valeric, capric, caproic, caprylic and pelargonic acids, ethyl acetate, ethyl proprionate, ethyl, propyl and butyl ethers, pentanol, hexanol, heptanol, octanol, nonanol, methane, ethane, propane, butane, pentane, hexane, heptane, decane, ethene, butene, octene, decene, tridecene, pentadecene, benzene, toluene, naphthalene, ethylenechloride, chloroform, carbon tetrachloride, nitrohexane, nitroheptane, nitrodecane, caprylamide, octylamine, ethyl-mercaptan, dimethylsulfoxide, thioesters, liquid ammonia, liquid sulphur dioxide, liquid hydrogen fluoride, liquid nitrogen and liquid helium. Quaternary ammonium compounds are adsorbed on or eluted from such high molecular weight polymers containing cation exchange groups. These quaternary ammonium compounds can be halide or hydroxide derivatives in which the quaternary component is alkyltrimethyl ammonium. The alkyl group (or groups) of these quaternary ammonium compounds can contain from 8 to 22 carbon atoms and can be saturated or unsaturated. Dimethyldidodecyl ammonium chloride, trimethyldidecyl ammonium chloride, dimethyldioctadecylammonium chloride, trimethyloctadecylammonium chloride, dodecyldimethylbenzyl-ammonium chloride, octadecyldimethybenzylammonium chloride, (p - diiso butylphenoxethoxy) ethylbenzyldimethylammonium chloride, trimethyloctylammonium-chloride, dimethyldodecylbenzylammonium chloride and methyltrioctadecylammonium chloride, trimethyl "coco" ammonium chloride, dimethyldi "tallow" ammonium chloride and trimethyl "soya" ammonium chloride, are examples of such quaternary ammonium compounds. Specifically exemplified are the separation of trimethyloctadecyl ammonium hydroxide, chloride, acetate or stearate in chloroform using a cellulose citrate, carboxymethyl cellulose or cellulose phosphate. Also exemplified are the use of butanol or ethyl acetate acidified with hyrochloric acid and substantially saturated with water as eluants for the quaternary compound. Antipyrine and copper ions can be eluted with chloroform and xylene together with hydrochloric acid and 8-hydroxyquinoline respectively. Dicarboxylic acids containing from 4 to 8 carbon atoms may be selectively eluted from the citrate ester of cellulose buffered with water at pH 5,4 with an amount of butanol in chloroform as the eluant the acids of greater chain length being desorbed prior to those of shorter chain length. Monocarboxylic acids (e.g. fatty acids) may be selectively eluted from the free base form of dimethylaminoethyl ether of cellulose substantially saturated by water, by increasing the amount of n-butyl ether in Skelly B (petroleum ether fraction) the longer chain length acids are desorbed from the cellulose exchange prior to removal of acids of shorter chain length. Specifications 862,180 and 862,181 are referred to.ALSO:An ion exchange reaction, comprising the step of treating at least one ionizable substance and an insoluble, open-chain high molecular-weight polymer containing ion exchange groups in a polyphase solvent medium comprising an aqueous phase and a water-immiscible phase to effect an interchange of ions. This insoluble ion exchanger may be amylose, amylopectin, inulins, alpha cellulose, oxycellulose, xylans, pectins, algins, glycogens, chitins, chondriotin sulphuric acid, heparin, hyaluronic acid, levans and dextrans. A preferred ion-exchanger can be derived from paper, cotton, wood pulp and cotton cloth and may be in the form of sheeting, belting, pressed solids or finely divided particles. These ion exchange groups may be either acidic (cation exchanger) e.g. a carboxyl group, or basic (anion exchanger), e.g. primary, secondary and tertiary amino groups or quaternary ammonium salts. The non-aqueous solvents may be methylethyl ketone, methylisobutyl ketone, diethyl ketone, methylamyl ketone, butanal, pentanal, hexanal, heptanal, valeric, capric, caproic, caprylic and pelargonic acids, ethyl acetate, ethyl propionate, ethyl, propyl and butyl ethers, pentanol, hexanol, heptanol, octanol, nonanol, methane, ethane, propane, butane, pentane, hexane, heptane, decane, ethene, butene, octene, decene, tridecene, pentadecene, benzene, toluene, naphthalene, ethylene chloride, chloroform, carbon tetrachloride, nitrohexane, nitroheptane, nitrodecane, caprylamide, octylamine, ethyl-mercaptan, dimethylsulfoxide, thioesters, liquid ammonia, liquid sulphur dioxide, liquid hydrogen fluoride, liquid nitrogen and liquid helium.