Matias, I., et. al, recently published an article in Biomolecules on a topic that I've been interested in and discussing for a few years; the use of LC-MS/MS in clinical labs for biomarkers, therapeutic drug monitoring and canabinoids. Not satisfied with just LC-MS/MS, they included GC-MS/MS in their work to provide a complete set of tools for their clinical studies using technologies that are seeing growth in clinical laboratories.
Interestingly, they applied the concepts from bioanalytical guidance (FDA, EMA, ICH M10) in assessing the quality of the assays: linearity, selectivity, determination of lower limit of quantification (LLOQ), matrix effect, carry-over, and within- and between -run determination of accuracy and precision. All of the stability parameters (during the preparation of samples in the biological matrix, post-preparative auto-sampler stability, solvent stability at room temperature (RT) and -20C for refence standards, and freeze-thaw stability and frozen storage stability in matrix.
They also compared the performance of the calibration curves when prepared in methanol, a surrogate matrix or the biological matrix. Unsurprisingly, the methanol calibrators performed optimally, with mixed performance for the calibrator curves for the 11 steroids and 7 canabinoids in the surrogate matrix and biological matrix. Methanol homogenized plasma as applied to C18 SPE for the steroid extraction; while canabinoids were extracted from plasma mixed with chloroform & methanol using LLE. The steroid were freed from extracted lipids prior to derivatization for GC-MS/MS. I mention this extraction procedures and the performance of the calibrators in methanol as they may not have been optimized for the chemical breadth of analytes being extracted. This is also noted in the matrix effect measurements for many of the analytes at low and mid QC concentrations.
They noted that "methods meet the stated criteria for recurrent measurement of STs and CBs in human plasma and saliva, as well as in plasma and tissue samples (small brain areas, tissues, and organs) from animal models". Which for biomarkers are a key accomplishment - the ability to provide reliable data at the quality needed to support the study endpoints. I don't currently have access to the CLSI guide for LC-MS/MS assay validation, but would love to compare those recommendations to what this group of researchers performed for a clinical laboratory.
I've not delved into further details and recommend you explore them for yourself in the article.
Biomolecules 2023, 13(2), 383; https://doi.org/10.3390/biom13020383
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