High resolution mass spectrometry newborn screening applications for quantitative analysis of amino acids and acylcarnitines from dried blood spots

• Published in: Analytica chimica acta Vol. 1120; no. C; pp. 85 - 96
• Main Authors: Pickens, C. Austin, Petritis, Konstantinos
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 11.07.2020; Elsevier
• Subjects: Amino Acids - blood; Amino acids and acylcarnitines; Dried blood spot; Dried Blood Spot Testing; High resolution mass spectrometry; Humans; Infant, Newborn; Mass Spectrometry; Metabolic disorders; Metabolomics; Neonatal Screening; Newborn screening; Newborn screening; High resolution mass spectrometry; Metabolomics; Dried blood spot; Metabolic disorders; Amino acids and acylcarnitines
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2020.04.067

Amino acid and acylcarnitine first-tier newborn screening typically employs derivatized or non-derivatized sample preparation methods followed by FIA coupled to triple quadrupole (TQ) MS/MS. The low resolving power of TQ instruments results in difficulties distinguishing nominal isobaric metabolites, especially those with identical quantifying product ions such as malonylcarnitine (C3DC) and 4-hydroxybutylcarnitine (C4OH). Twenty-eight amino acids and acylcarnitines extracted from dried blood spots (DBS) were analyzed by direct injection (DI)-HRMS on a Q-Exactive Plus across available mass resolving powers in SIM, in PRM at 17,000 full width at half maximum (FWHM), and a developed SIM/PRM hybrid MS method. Most notably, quantitation of C3DC and C4OH was successful by HRMS in non-derivatized samples, thus, potentially eliminating sample derivatization requirements. Quantitation differed between SIM and PRM acquired data for several metabolites, and it was determined these quantitative differences were due to collision energy differences or kinetic isotope effects between the unlabeled metabolites and the corresponding labeled isotopologue internal standards. Overall quantitative data acquired by HRMS were similar to data acquired on TQ MS/MS platform. A proof-of-concept hybrid DI-HRMS and SIM/PRM/FullScan method was developed demonstrating the ability to hybridize targeted newborn screening with metabolomic screening. [Display omitted] •Data acquired by HRMS and triple quadrupole were similar.•Direct injection HRMS platform overcame newborn screening limitations.•HRMS allowed combining untargeted metabolomic screening with targeted screening.•Identified fragmentation differences in unlabeled metabolites and labeled standards.