A improved method for preparing a concentrated meconium extract containing basic and acid-neutral target analytes present in a meconium sample suspected of containing the target analytes is provided. The meconium sample is extracted with a mixed solvent of acetonitrile and a volatile organic acid and the resulting organic phase is separated. The organic phase is diluted with water to provide an organic solution which is passed through a mixed mode solid phase extraction column having strong cation exchange and hydrophobic functionality. Acid-neutral and basic target analytes are sequentially eluted from the column and the eluates are combined to form a combined extract. The combined extract is evaporated to dryness and reconstituted in buffer to provide a clean concentrated neonatal meconium extract for use in qualitative and quantitative analyses.
