A RAPID PROCEDURE FOR THE DETERMINATION OF CAFFEINE, THEOPHYLLINE ANDTHEOBROMINE IN URINE BY MICELLAR LIQUID-CHROMATOGRAPHY AND DIRECT SAMPLE INJECTION

A liquid chromatographic procedure for the determination of caffeine, theophylline and theobromine in urine samples is described. The propos ed system uses a Spherisorb octadecyl-silane ODS-2 C-18 analytical col umn and a guard column of similar characteristics. The UV detector was set at 273 nm. A study to adequately select the composition of the mi cellar mobile phase for the separation of these compounds in urine sam ples is performed. Maximum resolution was achieved with a 0.075 M sodi um dodecylsulphate-1.5% propanol eluent. Limits of detection at 273 nm ranged between 0.4 mu g/ml for theobromine and theophylline and 1.2 m u g/ml for caffeine. The procedure allows the determination of these c ompounds in 10 min and it can be very useful in the control of doping.