Inorganic salts as hold-up time markers in C-18 columns

A systematic study of the retention behaviour in a C-18 reversed phase liqu id chromatography (RPLC) system of several inorganic salts, namely NaNO2, N aNO3, KBr, Bu4NBr and K2Cr2O7, is presented. The behaviour of the markers i n unbuffered mobile phases and the marker retention dependence on the pH an d ionic strength of the buffered mobile phases have been analyzed. In addit ion, a comparison between the retention behaviour of the markers and severa l ionizable analytes in buffered eluents is presented. (C) 2000 Elsevier Sc ience B.V. All rights reserved.