DETERMINATION OF PHENOLS, INORGANIC ANIONS, AND CARBOXYLIC-ACIDS IN KRAFT BLACK LIQUORS BY CAPILLARY ELECTROPHORESIS

Two methods are presented for the quantitative capillary electrophoret ic (CE) determination of phenolic lignin degradation compounds as well as of inorganic anions and organic acids in Kraft black liquors, Impo rtant phenolic lignin degradation compounds can be rapidly separated b y co-electroosmotic CE after acidification of the liquors and subseque nt extraction of the compounds with chloroform, A capillary electropho retic separation of phenolic compounds is performed by using a phospha te/borate electrolyte system and UV detection at 214 nm, In addition, a HPLC method using a gradient with mater, methanol, and acetic acid i s also developed, Inorganic ions which are of importance to the pulpin g process can be determined by simply diluting the black liquors after sampling and subsequent analysis with a chromate electrolyte system a nd indirect UV detection at 185 nm, In addition, the concentration of low molecular aliphatic carboxylic acids can be determined simultaneou sly within the same run, By method optimization it is possible to sepa rate the anions within one minute and, at the same time, to increase t he resolution of the solutes. The electrolyte systems for the CE separ ations were optimized by varying the pH value and by adding organic so lvents, Short separation times are obtained by adding a polycationic E OF modifier (hexadimethrine bromide) to the electrolyte which reverses the electroosmotic flow, A migration of the anionic analytes in the s ame direction as the electroosmotic now is thus established.