Identification of a frit-related sample carryover in newborn screening by tandem mass spectrometry

Kyunghun Kim; Howon Lee; Jeong Joong Lee; Kyoungho Cha; Nam Hyun Park; Young Keun Shin; Hyojin Chae; Eun-Jee Oh

doi:10.1016/j.jmsacl.2023.01.001

Identification of a frit-related sample carryover in newborn screening by tandem mass spectrometry

J Mass Spectrom Adv Clin Lab. 2023 Jan 5:27:56-60. doi: 10.1016/j.jmsacl.2023.01.001. eCollection 2023 Jan.

Authors

Kyunghun Kim¹, Howon Lee¹, Jeong Joong Lee¹, Kyoungho Cha¹, Nam Hyun Park², Young Keun Shin³, Hyojin Chae¹, Eun-Jee Oh¹

Affiliations

¹ Department of Laboratory Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
² Bio-Medical Science Co., Ltd, Seoul, Republic of Korea.
³ Waters Korea Ltd, Seoul, Republic of Korea.

Abstract

The need for high-throughput analysis of multiple analytes for inborn errors of metabolism in newborn screening (NBS) has led to the introduction of tandem mass spectrometry (MS/MS) into the NBS laboratory. In a flow-injection analysis (FIA), the predominant MS/MS method utilized for NBS, samples are introduced directly into the mass spectrometer without chromatographic separation. When a high-throughput FIA-based MS/MS method is implemented on newer generations of mass spectrometers with increased sensitivity, the risk of carryover and contamination increases. In the present study, we report the carryover of ornithine identified during the implementation of the NeoBase™ 2 (PerkinElmer) non-derivatized kits on the Xevo-TQD platform (Waters Corporation) and describe the source of the carryover, which was traced to the stainless-steel frit-type inline filter. Furthermore, a possible compound-dependent interaction with the stainless-steel frit is suggested based on the structure of ornithine and its effect on separation techniques. Investigation and mitigation of carryover can be a time and resource consuming process, and to this end, our report on identification of a stainless-steel frit as the source of delayed elution and carryover of ornithine should be recognized as a rare, albeit possible source of carryover in FIA-MS/MS methods adopted for NST.

Keywords: Carryover; DBS, Dried blood spot; ESI, Electrospray ionization; FIA, Flow-injection analysis; FTN, Flow through needle; Flow injection analysis; H, high; HPLC, High performance liquid chromatography; IEM, Inborn errors of metabolism; IPA, Isopropanol; L, low; LC, Liquid chromatography; LLOQ, Lower limit of quantitation; MS, Mass spectrometer; MS/MS, Tandem mass spectrometry; NBS, Newborn screening; Newborn screening; Ornithine; PEEK, Polyetheretherketone; QC, Quality control; SM, Sample manager; TIC, Total ion chromatogram; Tandem mass spectrometry; UPLC, Ultra performance liquid chromatography; pI, Isoelectric point.