title: Detection of ritalinic acid in urine by thin-layer chromatography and gas chromatography.
abstract: A new method for the analysis of ritalinic acid, the major metabolite of methylphenidate in urine, is described. The procedure involves solid-phase extraction of ritalinic acid from urine using C-18 reverse phase columns. The ritalinic acid is methylated to form methylphenidate which, together with an internal standard, is then extracted into chloroform and analyzed by gas chromatography using a flame ionization detector. This procedure gives essentially quantitative recovery of ritalinic acid from 10 mL urine and is linear in the range of 0 to 10 micrograms/mL. A positive analysis for ritalinic acid is confirmed by thin-layer chromatography. Detection sensitivities of greater than or equal to 1 micrograms/mL urine were observed for both procedures.
mesh_terms: D002849:Chromatography, Gas / Q000379:methods; D002855:Chromatography, Thin Layer / Q000379:methods; D006801:Humans; D008774:Methylphenidate / Q000031:analogs & derivatives* / Q000652:urine
chemical_list: D008774:Methylphenidate; C009189:ritalinic acid