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

• Published in: Journal of mass spectrometry and advances in the clinical lab 2023-01, Vol.27, p.56-60
• Main Authors: Kim, Kyunghun, Lee, Howon, Lee, Jeong Joong, Cha, Kyoungho, Hyun Park, Nam, Shin, Young Keun, Chae, Hyojin, Oh, Eun-Jee
• Format: Article
• Language: English
• Subjects: Carryover; Flow injection analysis; Newborn screening; Ornithine; Short Report; Tandem mass spectrometry
• ISSN: 2667-145X; 2667-1468; 2667-145X
• DOI: 10.1016/j.jmsacl.2023.01.001

•Sample carryover in newborn screening test can increase false positive results.•The risk of carryover is increased with newer generations of mass spectrometers.•Column-related carryover due to a stainless-steel frit inline filter was detected.•Compound-dependent factor of stainless-steel frit-related carryover is suggested.•Routine backpressure monitoring and timely replacement of frit rings are mandatory. 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.