Clinical and Laboratory Standards Institute guideline C62—Liquid Chromatography-Mass Spectrometry Methods provides guidance for the development and verification of liquid chromatography-mass spectrometry (LC-MS) methods in the clinical laboratory. The document is intended to reduce interlaboratory variance for clinical assays through guidance for evaluating interferences, assay performance, and other pertinent characteristics. It emphasizes particular areas related to assay development and presents a standardized approach for method verification that is specific to mass spectrometry (MS) technology. This document is intended for laboratorians responsible for development and verification of MS-based assays, physicians who may use these assays for patient care decisions, external quality assessment programs, and manufacturers of MS instrumentation and reagent kits designed to be paired with a particular mass spectrometer. This document is limited to discussion of LC-MS and is focused on the steps for development of a method, eg, whether the analyte is a drug, hormone, protein, or peptide.

This guideline was revised in 2022 under the Limited Revision Process and replaces the first edition of the guideline, which was published in 2014. The sole change made in this edition is distinguishing recommended criteria for intralaboratory evaluation from studies required for regulatory submissions.

This document provides an introduction to, and guidance for, method development, verification, and postimplementation monitoring of quantitative clinical applications using liquid chromatography-mass spectrometry (LC-MS). While LC-MS may also be used for qualitative analyses, the focus of this document is on the use of this technology for quantification of clinical analytes. In addition, while there are commercial and research methods that allow direct injection without chromatography for rapid analyses, this guideline is exclusively focused on liquid chromatography (LC) coupled to mass spectrometry (MS). The purpose of this guideline is to educate both clinical LC-MS practitioners and health care providers (including physicians) who may use these assays for patient care decisions on the benefits and limitations of LC-MS methods used in the clinical laboratory, as well as provide a practical guide for the development and implementation of LC-MS–based clinical applications. It is intended to serve not only as a companion to CLSI document C50,1 which serves as excellent general guidance for MS in the clinical laboratory, but also to provide an enhanced focus on methods, best practices, and instrumentation related to LC-MS, which is emerging as the most common approach to clinical analyses. This document is also intended to be a resource for instrument manufacturers, manufacturers of LC-MS reagents, regulatory agencies, and educators, as well as individuals responsible for developing laboratory standards and policy.

A description of all current clinical applications of LC-MS, as well as all of the pertinent information regarding development and verification of these methods, is beyond the scope of this document. As such, this guideline directs the reader to appropriate existing resources wherever possible. In providing guidance for LC-MS method development, verification, and implementation, this document focuses on:

• Important features of LC-MS instrumentation

• Preexamination factors that can impact assay performance and utility

• Assay calibration

• Analytical variables important in method development

• Assay verification

• QA and QC

• Postimplementation monitoring of clinical methods