Improved separation and detection of picolinic acid and quinolinic acid by capillary electrophoresis-mass spectrometry: Application to analysis of human cerebrospinal fluid

• Published in: Journal of Chromatography A Vol. 1316; pp. 147 - 153
• Main Authors: Wang, Xiaochun, Davis, Ian, Liu, Aimin, Miller, Andrew, Shamsi, Shahab A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 05.11.2013; Elsevier
• Subjects: acetonitrile; Acetonitriles; Biological and medical sciences; biomarkers; Capillarity; capillary electrophoresis; Capillary electrophoresis-tandem mass spectrometry; Cerebrospinal fluid; Cerebrospinal fluid (biochemistry, cytology, circulation, manometry). Intracranial pressure determination; Chromatography; Chromatography, High Pressure Liquid; Coating; Disorders; early diagnosis; Electrophoresis, Capillary - methods; Human; Humans; Investigative techniques, diagnostic techniques (general aspects); kynurenine pathway; Limit of Detection; Linear Models; mass spectrometry; Medical sciences; Metabolites; Picolinic acid; Picolinic Acids - cerebrospinal fluid; Picolinic Acids - isolation & purification; Quaternary ammonium coated capillary; Quaternary Ammonium Compounds; Quinolinic acid; Quinolinic Acid - cerebrospinal fluid; Quinolinic Acid - isolation & purification; Reproducibility; Reproducibility of Results; Tandem Mass Spectrometry - methods; Picolinic acid; Cerebrospinal fluid; Quinolinic acid; Capillary electrophoresis-tandem mass spectrometry; Quaternary ammonium coated capillary; Capillary column; Human; Biological fluid; Tandem mass spectrometry; Nervous system diseases; Chemical analysis; Organic cation; Capillary electrophoresis; Coupled method; Patient; Inflammation; Electrospray; Coated material; Quaternary ammonium compound; Clinical biology
• ISSN: 0021-9673; 1873-3778
• DOI: 10.1016/j.chroma.2013.09.085

•Compare the CE-ESI-MS/MS, HPLC–ESI-MS/MS and nano LC–Chip/ESI-MS/MS methods.•Compare the cationic (quaternary ammonium) and anionic (sulfonated) coated capillaries in CE-ESI-MS/MS.•Improve peak shape and sensitivity in CSF by a simple ACN stacking method.•The LOQ of picolinic acid and quinolinic acid were 20nM and 400nM, respectively.•Human CSF samples were successfully analyzed by CE-ESI-MS/MS method. “Quinolinic acid (QA)”, a metabolite of the kynurenine pathway (KP), is implicated as a major neurological biomarker, which causes inflammatory disorders, whereas there is an increase evidence of the role of picolinic acid (PA) in neuroinflammation. Therefore, there is an urgent need to develop new clinical test for early diagnosis of neuroinflammatory disorders. A comparison is made between three different platforms such as high performance liquid chromatography–electrospray mass spectrometry (HPLC–ESI-MS/MS), nano LC–Chip/ESI-MS/MS, as well as the use of cationic (quaternary ammonium) and anionic (sulfonated) coated capillaries in capillary electrophoresis (CE)-ESI-MS/MS. The comparison revealed that CE-ESI-MS/MS method using a quaternary ammonium coated capillary is the best method for analysis of PA and QA. A simple stacking procedure by the inclusion of acetonitrile in the artificial cerebrospinal fluid (CSF) sample was employed to improve the peak shape and sensitivity of KP metabolites in CE-ESI-MS/MS. The developed CE-ESI-MS/MS assay provided high resolution, high specificity and high sensitivity with a total analysis time including sample preparation of nearly 12min. In addition, excellent intra-day and inter-day repeatability of migration times and peak areas of the metabolites were observed with respective relative standard deviation (RSD) of less than 2.0% and 2.5%. Somewhat broader variations in repeatability for a 3 independently prepared coated capillary (total 35 runs each) with % RSD up to 3.8% and 5.8% was observed for migration time and peak areas, respectively. Artificial CSF was used as a surrogate matrix to simultaneously generate calibration curves over a concentration range of 0.02–10μM for PA and 0.4–40μM for QA. The method was then successfully applied to analyze PA and QA in human CSF, demonstrating the potential of this CE-ESI-MS/MS method to accurately quantitate with high specificity and sensitivity.