A rapid procedure for the determination of caffeine, theophylline and theobromine 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 proposed system uses a Spherisorb octadecyl-silane ODS-2 C18 analytical column and a guard column of similar characteristics. The UV detector was set at 273 nm. A study to adequately select the composition of the micellar mobile phase for the separation of these compounds in urine samples is performed. Maximum resolution was achieved with a 0.075 M sodium dodecylsulphate-1.5% propanol eluent. Limits of detection at 273 nm ranged between 0.4 μg/ml for theobromine and theophylline and 1.2 μg/ml for caffeine. The procedure allows the determination of these compounds in 10 min and it can be very useful in the control of doping.