Comparison of retention indices of some explosives and related compounds calculated by different mathematical methods in reversed-phase liquid chromatography

In reversed phase liquid chromatography, the retention indices of some neut ral and acidic explosives and related compounds (nitramines, nitroaromatics , aminoaromatics, and nitrophenols) based on the alkan-2-one, alkyl aryl ke tone, and 1-nitroalkane retention index standards hare been determined by t he application of a new mathematical adaptation method, viz. a multiparamet ric least-squares regression iterative method. This method was applied to t wo types of columns, The first group includes six octadecyl-C-18 columns wi th different packing materials and obtained from different manufacturers, w hile the second group comprises one octyl-C-8 column. The retention indices have been extensively studied using either methanol-w ater or methanol-phosphate buffer mobile phase systems. The calculated mult iparametric retention indices values were compared with those obtained by G uardino's, Grobler's, and Kovats' methods. The influences of the concentrat ion of the organic modifier in the mobile phase, aqueous mobile phase pH, a nd the column packing material on the retention indices of the explosives w ere also investigated. Good agreement was observed between the retention in dices calculated by the use of the four mathematical methods for both neutr al and acidic explosives.