A simple and robust liquid chromatography tandem mass spectrometry assay for determination of plasma free metanephrines and its application to routine clinical testing for diagnosis of pheochromocytoma

Recent Advances in Catecholamines Analytical Detection Methods and Their Pretreatment Technologies

Catecholamines (CAs), including adrenaline, noradrenaline, and dopamine, are neurotransmitters and hormones that play a critical role in regulating the cardiovascular system, metabolism, and stress response in the human body. As promising methods for real-time monitoring of catecholamine neurotransmitters, LC-MS detectors have gained widespread acceptance and shown significant progress over the past few years. Other detection methods such as fluorescence detection, colorimetric assays, surface-enhanced Raman spectroscopy, and surface plasmon resonance spectroscopy have also been developed to varying degrees. In addition, efficient pretreatment technology for CAs is flourishing due to the increasing development of many highly selective and recoverable materials. There are a few articles that provide an overview of electrochemical detection and efficient enrichment, but a comprehensive summary focusing on analytical detection technology is lacking. Thus, this review provides a comprehensive summary of recent analytical detection technology research on CAs published between 2017 and 2022. The advantages and limitations of relevant methods including efficient pretreatment technologies for biological matrices and analytical methods used in combination with pretreatment technology have been discussed. Overall, this review article provides a better understanding of the importance of accurate CAs measurement and offers perspectives on the development of novel methods for disease diagnosis and research in this field.

Current Sample Preparation Methodologies for Determination of Catecholamines and Their Metabolites

Catecholamines (CAs) and their metabolites play significant roles in many physiological processes. Changes in CAs concentration in vivo can serve as potential indicators for the diagnosis of several diseases such as pheochromocytoma and paraganglioma. Thus, the accurate quantification of CAs and their metabolites in biological samples is quite important and has attracted great research interest. However, due to their extremely low concentrations and numerous co-existing biological interferences, direct analysis of these endogenous compounds often suffers from severe difficulties. Employing suitable sample preparation techniques before instrument detection to enrich the target analytes and remove the interferences is a practicable and straightforward approach. To date, many sample preparation techniques such as solid-phase extraction (SPE), and liquid-liquid extraction (LLE) have been utilized to extract CAs and their metabolites from various biological samples. More recently, several modern techniques such as solid-phase microextraction (SPME), liquid-liquid microextraction (LLME), dispersive solid-phase extraction (DSPE), and chemical derivatizations have also been used with certain advanced features of automation and miniaturization. There are no review articles with the emphasis on sample preparations for the determination of catecholamine neurotransmitters in biological samples. Thus, this review aims to summarize recent progress and advances from 2015 to 2021, with emphasis on the sample preparation techniques combined with separation-based detection methods such capillary electrophoresis (CE) or liquid chromatography (LC) with various detectors. The current review manuscript would be helpful for the researchers with their research interests in diagnostic analysis and biological systems to choose suitable sample pretreatment and detection methods.

Quantitative Measurement of Plasma Free Metanephrines by a Simple and Cost-Effective Microextraction Packed Sorbent with Porous Graphitic Carbon and Liquid Chromatography-Tandem Mass Spectrometry

Plasma free metanephrines are widely used for the diagnosis of pheochromocytoma and paraganglioma (PPGL), yet quantifying metanephrines using a simple and cost-effective approach may be challenging due to preanalytical and analytical constraints. In this study, we established and validated a new method for quantitative measurement of plasma free metanephrines based on microextraction by packed sorbent (MEPS) with porous graphitic carbon (PGC) and liquid chromatography-tandem mass spectrometry (HILIC-MS/MS). The elution step was fully compatible with HILIC mode without evaporation and reconstitution. The analytes were well resolved, and potential interferences (54 substances) were investigated. This method was linear from 24.7-2717 pg/mL for metanephrine (MN) and 24.5-4010 pg/mL for normetanephrine (NMN) with a coefficient of determination (R ²) higher than 0.994. The limit of MN and NMN detection were 12.4 pg/mL and 12.3 pg/mL, respectively. The intra- and interassay impressions were ≤12.8% for spiked quality controls and ≤13.6% for commercial quality controls; the method recoveries ranged within 88.0-109.0%, respectively. The area under the receiver operating characteristic (ROC) curve was 0.848 ± 0.047 for MN and 0.979 ± 0.021 for NMN. Validation that was performed by comparing clinical specimens with various biochemical results showed that plasma free metanephrines in a seated position had comparable sensitivity and lower specificity to urinary free metanephrines, which could be compensated by combining other biochemical tests. The newly developed MEPS method resulted as a time-saving, reliable, and cost-effective microextraction technique that can be applied for a successful screening of PPGL.