Application of the thermally tuned tandem column concept to the separationof several families of environmental toxicants

Separations of several families of environmental toxicants were optimized b y means of the thermally tuned tandem column ((TC)-C-3) concept. We use a t andem combination of an octadecylsilane (ODS) and a carbon-coated zirconia (C-ZrO2) column; and tune the selectivity by independently adjusting the is othermal temperatures of the two columns. This results in the change in the contribution that each column makes to the overall retention and selectivi ty, The separation was optimized by locating the optimum pair of column tem peratures which give the best separation of the critical solute pair. For b oth triazine herbicides and carbamate pesticides samples, dramatically diff erent selectivities and different critical pairs were observed for the two types of phases. Although neither individual phase gave adequate separation , the (TC)-C-3 approach provided baseline separations using only four preli minary trial separations. We also showed that, for the triazine samples, th e (TC)-C-3 approach gave a better separation than did conventional mobile p hase optimization with an ODS column. The combination of superior selectivi ty of (TC)-C-3 and high now rate allows the baseline separation of complex mixtures in just a few minutes.