Abstract

Methylphenidate (MPH) is therapeutically used for the treatment of attention-deficit/hyperactivity disorder (ADHD). In sports it can be abused to overcome fatigue or to increase the tolerance to exhaustion. Less than l% of the administered dose is excreted unchanged in urine whereas 80% is excreted as ritalinic acid (RA). Moreover RA can be detected much longer in urine than MPH. Hence RA is the preferred target compound to detect MPH administration. In our laboratory stimulants are screened for by GC/MS using MSTFA as derivatisating agent alter liquid/liquid-extraction at pH 9.2. Unfortunately RA can not be detected by this procedure because MBTFA is necessary for its derivatisation. Moreover, even when MBTFA is used our liquid-liquid extraction at pH 9.2 does not allow to detect RA at the MRPL of 500 ng/ml. Therefore it was decided to include this compound into the LC-MS screening method for diuretics. Using this LC-MS2 screening method, the detection of RA can be guaranteed at the MRPL. For confirmation purposes, the ion trap parameter Qz-value had to be adjusted. The method has been used routinely since one year and 3 samples were reported as an adverse analytical finding, containing RA. No MPH was detected in these samples. Aus dem Text (geändert)