Gas chromatographic–mass spectrometric screening for organic acidemias using dried urine filter paper: determination of α-ketoacids

There are several organic acid disorders that require information on α-ketoacids, such as maple syrup urine disease or α-ketoadipic acidemia. The recovery, stability and diagnostic availability of α-ketoacids in dried urine filter paper analyzed by GC–MS with oxime-trimethylsilyl derivatization was studied for organic acidemia screening. The recovery of all nine types of α-ketoacids tested, but for phenylpyruvate, 2-ketoadipate, and p-OH-phenylpyruvate, from filter paper samples was acceptable. The stability of pyruvate, branched-chain α-ketoacids, α-ketoadipate and α-ketoglutarate was stable for at least 28 days, although some α-ketoacids such as succinylacetone were unstable. It indicated it was difficult to diagnose only tyrosinemia type 1 among nine specimens from organic acidemia patients tested. The method could be applied to global organic acidemia screening.