Fig. 2.

A representative chromatogram obtained from a healthy control newborn. Y-axis represents relative intensity normalized to the enzyme reaction product as 100%. For the enzyme reaction, a 3-mm punch of DBS was reacted as described in Experimental Procedure at 37 °C for 20 h. Enzyme reaction products were extracted into ethyl acetate, dried under nitrogen stream and solubilized with Reconstitution solvent (300 μL) and injected onto UPLC-MS/MS (5 μL). Black line represents the chromatogram for the product of enzyme reaction and gray line represents that for IS.