Improving harmonization and standardization of expanded newborn screening results by optimization of the legacy flow injection analysis tandem mass spectrometry methods and application of a standardized calibration approach

Carling, Rachel S., Whyte, Emily, John, Catharine, Garstone, Rachelle, Goddard, Philippa, Greenfield, Toby, Hogg, Sarah L, Le Masurier, Clare, Cowen, Simon, Moat, Stuart J and Hopley, Christopher 2022. Improving harmonization and standardization of expanded newborn screening results by optimization of the legacy flow injection analysis tandem mass spectrometry methods and application of a standardized calibration approach. Clinical Chemistry 68 (8) , pp. 1075-1083. 10.1093/clinchem/hvac070

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Abstract

Background Newborn screening (NBS) laboratories in the United Kingdom adhere to common protocols based on single analyte cutoff values (COVs); therefore, interlaboratory harmonization is of paramount importance. Interlaboratory variation for screening analytes in UK NBS laboratories ranges from 17% to 59%. While using common stable isotope internal standards has been shown to significantly reduce interlaboratory variation, instrument set-up, sample extraction, and calibration approach are also key factors. Methods Dried blood spot (DBS) extraction processes, instrument set-up, mobile-phase composition, sample introduction technique, and calibration approach of flow injection analysis–tandem mass spectrometry (FIA-MS/MS) methods were optimized. Inter- and intralaboratory variation of methionine, leucine, phenylalanine, tyrosine, isovaleryl-carnitine, glutaryl-carnitine, octanoyl-carnitine, and decanoyl-carnitine were determined pre- and postoptimization, using 3 different calibration approaches. Results Optimal recovery of analytes from DBS was achieved with a 35-min extraction time and 80% methanol (150 μL). Optimized methodology decreased the mean intralaboratory percentage relative SD (%RSD) for the 8 analytes from 20.7% (range 4.1–46.0) to 5.4% (range 3.0–8.5). The alternative calibration approach reduced the mean interlaboratory %RSD for all analytes from 16.8% (range 4.1–25.0) to 7.1% (range 4.1–11.0). Nuclear magnetic resonance analysis of the calibration material highlighted the need for standardization. The purities of isovaleryl-carnitine and glutaryl-carnitine were 85.13% and 69.94% respectively, below the manufacturer’s stated values of ≥98%. Conclusions For NBS programs provided by multiple laboratories using single analyte COVs, harmonization and standardization of results can be achieved by optimizing legacy FIA-MS/MS methods, adopting a common analytical protocol, and using standardized calibration material rather than internal calibration.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Medicine
Publisher:	American Association for Clinical Chemistry
ISSN:	0009-9147
Date of First Compliant Deposit:	28 October 2022
Date of Acceptance:	28 March 2022
Last Modified:	17 May 2023 20:51
URI:	https://orca.cardiff.ac.uk/id/eprint/153771

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