This NeoMass AAAC 3.0 kit is for the quantitative measurement of 15 amino acids, free carnitine, 12 acylcarnitines, argininosuccinic acid, succinylacetone, lysophospholipid and nucleoside in blood samples dried on filter paper as a primary test for screening of newborns for inborn errors of metabolism. The kit includes isotopically labeled internal standards necessary for quantifying all of these analytes. In addition, the methodology enables also determination of additional naturally occurring acylcarnitines by using the corresponding internal standards for their quantitation.