Uelerate the phases separation, the tube was then imtroduced in an ice bath for 5 min. the phases wewe seprated by cantrifugation fot 10 min at 1000 rpm. The aqueous phase was removed with a glass pipette, and 15 of the formed IL (li,(hmim)(PF6) was withdrawn with a syringe, and deposited in a vial for dilution with 15 L of acetonitrile. Finally, 10 L of the minture was deposited on a tungsten coil surface for analysis. A schematic diagram of the analytical method is depicted in fig 1. For Cr(vi)determination, the only difference was that the volume of DDTC solution was reduced to 0.1 mL and the pH of the sample was fixed at 2 with buffer solutionnder optimum conditions for total Cr detdrmination at pH 5,o.2 mL (hmim)(C) IL solution, corresponding to 60 mg. was placed in a conical-bottom glass tube and dissolved in 10 mL of aqueous standards or sample solutions. Then, 0.5 mL DDTC complexant solution (10%,w/v)and 0.5 mL buffer solution (pH 5,2 mol/L) were added. Next, an equimolr quantity of KPF6(55 mg)relative to (Hmim)(C) was added and a cloudy solution was immediately formed. The mixture was manually shaken for 0.5 min. In order to acc