Measurement of alloisoleucine and branched-chain amino acids in dried blood spot using the QSight 210 MD Mass Spectrometer

In this application note, a gradient LC-MS/MS method is presented for quantifying Allo-Ile concentration in dried blood spot (DBS) in order to allow more specific marker measurement and to reduce false-positive rates (also diet-related) in maple syrup urine disease (MSUD) screening.