CLN Article

Validation Resources for Clinical Mass Spectrometry

William Clarke, PhD, MBA, DABCC

Mass spectrometry is emerging as an important technology for clinical laboratories. In addition to the availability of more clinical applications, the evolution of mass spectrometry technology is another important factor behind its increased uptake in clinical labs. Instrumentation now is more robust, and vendors have developed user interfaces that make it possible for novice users to access and successfully implement the technology in their labs. One does not have to have an advanced degree in analytical chemistry to use mass spectrometry.

As more clinical laboratorians from a wide variety of backgrounds employ mass spectrometry for clinical analyses, the need for resources to guide method development and validation has become clear. Fortunately, many such resources are available in a wide variety of formats. Each mass spectrometry vendor has recognized the potential in the emerging clinical market, and each offers various forms of support for method development, primarily in the form of guidance for general method development as well as proper utilization and maintenance of instruments.

Another good source for guidance is at various conferences focused on mass spectrometry. The American Society for Mass Spectrometry Annual Meeting typically offers pre-conference courses on various aspects of method development, and there is an active group within the association focused on clinical mass spectrometry. In addition, there are other smaller meetings focused exclusively on clinical mass spectrometry, including the annual Mass Spectrometry Applications for the Clinical Laboratory meeting in California and the upcoming AACC 5th Annual Mass Spectrometry and Separation Sciences for Laboratory Medicine Conference, October 1–2 in Chicago. Both of these venues offer education on method development.

Laboratory professionals also should become familiar with guidance documents that include information on method validation. For instance, the Scientific Working Group for Forensic Toxicology has developed and made available online a guidance document for method validation in forensic toxicology ( In addition, both the Food and Drug Administration and the European Medicines Agency have published guidance documents that outline metrics for validation of bioanalytical methods, as well as performance targets for methods being used in clinical studies for regulatory submission.

One of the common threads for each of these documents is that they are geared toward liquid chromatography-mass spectrometry (LC-MS) methods used primarily for batch analyses in larger clinical trials. While many of the documents’ recommendations also are valid for clinical analyses, it is important to acknowledge an important difference: in the clinical laboratory, the batches are much smaller and analyses are performed longitudinally over the course of weeks, months, and years.

The Clinical Laboratory Standards Institute (CLSI) develops consensus guidelines for various technologies used in laboratory medicine, as well as common aspects of laboratory medicine that apply to all technologies. The important characteristic of these guidelines is that they take into account the longitudinal nature of testing in the clinical laboratory, as well as commonly used quality control (QC) and quality assurance (QA) practices. In 2007, CLSI moved to address mass spectrometry as an emerging technology in the clinical laboratory by releasing its guidance document C50-A, “Mass Spectrometry in the Clinical Laboratory: General Principles and Guidance,” an informational document that deals with clinical mass spectrometry in a broad way. In 2014, CLSI released a second mass spectrometry-focused document, C62-A, “Liquid Chromatography-Mass Spectrometry Methods,” focused on quantitative LC-MS methods for clinical analyses.

C62-A builds on the informational nature of the C50-A document, in that it begins with a discussion of both LC and MS instrumentation, thereby orienting new users to the technology they are preparing to implement in their labs. From there, C62-A offers guidance for best practices in LC-MS method development, with commentary on important factors that labs should consider to achieve the most robust method possible. The document then outlines validation parameters and performance targets specific to clinical laboratory analyses, referencing CLSI general laboratory guidelines when possible. Lastly, C62-A explains best practices for post-implementation performance monitoring and QA/QC to ensure longitudinal quality and robustness for clinical LC-MS methods.

A combination of the above resources offers both novice and experienced users the opportunity to institute best practices for their LC-MS method development and validation, and to maximize the potential of the technology in clinical analyses and patient care.

Disclosure: The author is the chair of the CLSI C62-A Document Development Committee and has both research and consulting relationships with Thermo Fisher Scientific.