ELECTROSPRAY TANDEM MASS-SPECTROMETRY IN THE DIAGNOSIS OF ORGANIC ACIDEMIAS

A novel procedure based on electrospray tandem mass spectrometry (ESI- MS/MS) has been used in the diagnosis of organic acidemias. The method is based on the determination of acylcarnitine profiles from blood sp ots collected on Guthrie cards. The acylcarnitines are extracted with methanol, derivatized to their butyl esters and analyzed by ESI-MS/MS. Precursor-ion scanning of the common fragment at m/z 85 of the butyl esters yields highly diagnostic acylcarnitine profiles. Analysis time is one minute per sample and is fully automated. Examples are given of normal profiles, of profiles from two patients with fatty acid oxidat ion defects, and of a case of propionic acidemia. The technique is sim ple, rapid and specific, and shows potential for routine application i n neonatal screening of organic acidemias.