Ion-neutral Clustering of Bile Acids in Electrospray Ionization Across UPLC Flow Regimes

AbstractBile acid authentic standards were used as model compounds to quantitatively evaluate complex in-source phenomenon on a UPLC-ESI-TOF-MS operated in the negative mode. Three different diameter columns and a ceramic-based microfluidic separation device were utilized, allowing for detailed descriptions of bile acid behavior across a wide range of flow regimes and instantaneous concentrations. A custom processing algorithm based on correlation analysis was developed to group together all ion signals arising from a single compound; these grouped signals produce verified compound spectra for each bile acid at each on-column mass loading. Significant adduction was observed for all bile acids investigated under all flow regimes and across a wide range of bile acid concentrations. The distribution of bile acid containing clusters was found to depend on the specific bile acid species, solvent flow rate, and bile acid concentration. Relative abundancies of each cluster changed non-linearly with concentration. It was found that summing all MS level (low collisional energy) ions and ion-neutral adducts arising from a single compound improves linearity across the concentration range (0.125–5 ng on column) and increases the sensitivity of MS level quantification. The behavior of each cluster roughly follows simple equilibrium processes consistent with our understanding of electrospray ionization mechanisms and ion transport processes occurring in atmospheric pressure interfaces. Graphical Abstractᅟ

[1]  M. Gamero-Castaño,et al.  Mechanisms of electrospray ionization of singly and multiply charged salt clusters , 2000 .

[2]  T. Benter,et al.  Studies of the mechanism of the cluster formation in a thermally sampling atmospheric pressure ionization mass spectrometer. , 2014, The Review of scientific instruments.

[3]  J. Todd,et al.  Atmospheric pressure ionization mass spectrometry , 1983 .

[4]  P. Brown,et al.  Effects of mobile-phase additives, solution pH, ionization constant, and analyte concentration on the sensitivities and electrospray ionization mass spectra of nucleoside antiviral agents. , 1999, Analytical chemistry.

[5]  P. Kebarle,et al.  Dependence of ion intensity in electrospray mass spectrometry on the concentration of the analytes in the electrosprayed solution , 1993 .

[6]  J. V. Iribarne,et al.  On the evaporation of small ions from charged droplets , 1976 .

[7]  G. Trugnan,et al.  Bile acid profiling in human biological samples: comparison of extraction procedures and application to normal and cholestatic patients. , 2012, Journal of chromatography. B, Analytical technologies in the biomedical and life sciences.

[8]  J. V. Iribarne,et al.  Field induced ion evaporation from liquid surfaces at atmospheric pressure , 1979 .

[9]  R. Abagyan,et al.  XCMS: processing mass spectrometry data for metabolite profiling using nonlinear peak alignment, matching, and identification. , 2006, Analytical chemistry.

[10]  Timothy M. D. Ebbels,et al.  Correction of mass calibration gaps in liquid chromatography-mass spectrometry metabolomics data , 2010, Bioinform..

[11]  Michael Karas,et al.  Nanoelectrospray—More than just a minimized-flow electrospray ionization source , 1999, Journal of the American Society for Mass Spectrometry.

[12]  T. Benter,et al.  The role of ion-bound cluster formation in negative ion mass spectrometry. , 2012, Rapid communications in mass spectrometry : RCM.

[13]  J. Fenn,et al.  Formation of charged clusters during electrospray ionization of organic solute species , 1991 .

[14]  M. Mcphail,et al.  Bile acid profiling and quantification in biofluids using ultra-performance liquid chromatography tandem mass spectrometry. , 2015, Analytical chemistry.

[15]  L. Piater,et al.  Collision energy alteration during mass spectrometric acquisition is essential to ensure unbiased metabolomic analysis , 2012, Analytical and Bioanalytical Chemistry.

[16]  Anneli Kruve,et al.  Adduct Formation in ESI/MS by Mobile Phase Additives , 2017, Journal of The American Society for Mass Spectrometry.

[17]  Russ Rew,et al.  NetCDF: an interface for scientific data access , 1990, IEEE Computer Graphics and Applications.

[18]  J. Hayes,et al.  Supersonic Jets, Rotational Cooling, and Analytical Chemistry , 1983 .

[19]  R. Whittal,et al.  Interferences and contaminants encountered in modern mass spectrometry. , 2008, Analytica chimica acta.

[20]  J. Fenn,et al.  Electrospray interface for liquid chromatographs and mass spectrometers. , 1985, Analytical chemistry.

[21]  M. Dziadosz.  Influence of buffer concentration on electrospray ionisation of γ-hydroxybutyrate adducts with the components of the mobile phase used in liquid chromatography-tandem mass spectrometry. , 2016, Journal of chromatography. B, Analytical technologies in the biomedical and life sciences.

[22]  Richard D. Smith,et al.  Charge competition and the linear dynamic range of detection in electrospray ionization mass spectrometry , 2004, Journal of the American Society for Mass Spectrometry.

[23]  T. Benter,et al.  Are Clusters Important in Understanding the Mechanisms in Atmospheric Pressure Ionization? Part 1: Reagent Ion Generation and Chemical Control of Ion Populations , 2014, Journal of The American Society for Mass Spectrometry.

[24]  J. V. Iribarne,et al.  Liquid ion evaporation/mass spectrometry/mass spectrometry for the detection of polar and labile molecules , 1982 .

[25]  David S. Wishart,et al.  HMDB 3.0—The Human Metabolome Database in 2013 , 2012, Nucleic Acids Res..

[26]  Gary J Patti,et al.  Defining and Detecting Complex Peak Relationships in Mass Spectral Data: The Mz.unity Algorithm. , 2016, Analytical chemistry.

[27]  J. Wolff,et al.  Accurate mass liquid chromatography/mass spectrometry on orthogonal acceleration time-of-flight mass analyzers using switching between separate sample and reference sprays. 1. Proof of concept. , 2000, Analytical chemistry.

[28]  I. Vidavsky,et al.  Comparing similar spectra: From similarity index to spectral contrast angle , 2002, Journal of the American Society for Mass Spectrometry.

[29]  R Core Team,et al.  R: A language and environment for statistical computing. , 2014 .

[30]  R. Cole,et al.  Atmospheric Pressure Ionization Mass Spectrometry , 2006 .

[31]  P. Kebarle,et al.  From ions in solution to ions in the gas phase - the mechanism of electrospray mass spectrometry , 1993 .

[32]  M. Karas,et al.  Effect of different solution flow rates on analyte ion signals in nano-ESI MS, or: when does ESI turn into nano-ESI? , 2003, Journal of the American Society for Mass Spectrometry.

[33]  Richard D. Smith,et al.  Physical/chemical separations in the break-up of highly charged droplets from electrosprays , 2001, Journal of the American Society for Mass Spectrometry.

[34]  A. Saba,et al.  Atmospheric pressure photoionization mass spectrometry. , 2003, Mass spectrometry reviews.

[35]  I. Wilson,et al.  UPLC/MS(E); a new approach for generating molecular fragment information for biomarker structure elucidation. , 2006, Rapid communications in mass spectrometry : RCM.

[36]  S Neumann,et al.  RAMClust: a novel feature clustering method enables spectral-matching-based annotation for metabolomics data. , 2014, Analytical chemistry.

[37]  J. Wolff,et al.  Accurate mass liquid chromatography/mass spectrometry on quadrupole orthogonal acceleration time-of-flight mass analyzers using switching between separate sample and reference sprays. 2. Applications using the dual-electrospray ion source. , 2001, Analytical chemistry.

[38]  R. C. Mobley,et al.  Molecular Beams of Macroions , 1968 .

[39]  A. Bruins,et al.  On cluster ions, ion transmission, and linear dynamic range limitations in electrospray (ionspray) mass spectrometry , 1997 .

[40]  Jan Lisec,et al.  Compound annotation in liquid chromatography/high-resolution mass spectrometry based metabolomics: robust adduct ion determination as a prerequisite to structure prediction in electrospray ionization mass spectra. , 2017, Rapid communications in mass spectrometry : RCM.

[41]  B. Thomson.  Atmospheric pressure ionization and liquid chromatography/mass spectrometry—together at last , 1998 .

[42]  S. Neumann,et al.  CAMERA: an integrated strategy for compound spectra extraction and annotation of liquid chromatography/mass spectrometry data sets. , 2012, Analytical chemistry.

[43]  Andrea Ganna,et al.  Enabling Efficient and Confident Annotation of LC-MS Metabolomics Data through MS1 Spectrum and Time Prediction. , 2016, Analytical chemistry.

[44]  E. De Pauw,et al.  Internal energy and fragmentation of ions produced in electrospray sources. , 2005, Mass spectrometry reviews.

[45]  Lars Konermann,et al.  Exploring the mechanism of salt-induced signal suppression in protein electrospray mass spectrometry using experiments and molecular dynamics simulations. , 2015, Analytical chemistry.

[46]  Xing-Fang Li,et al.  Liquid chromatography-electrospray mass spectrometric studies of ginkgolides and bilobalide using simultaneous monitoring of proton, ammonium and sodium adducts. , 2002, The Analyst.

[47]  M. Galceran,et al.  Ion-molecule adduct formation in tandem mass spectrometry , 2016, Analytical and Bioanalytical Chemistry.

[48]  Steffen Neumann,et al.  Highly sensitive feature detection for high resolution LC/MS , 2008, BMC Bioinformatics.

[49]  D. Scott,et al.  Optimization and testing of mass spectral library search algorithms for compound identification , 1994, Journal of the American Society for Mass Spectrometry.

[50]  Brandie M. Ehrmann,et al.  Investigations of analyte-specific response saturation and dynamic range limitations in atmospheric pressure ionization mass spectrometry. , 2014, Analytical chemistry.

[51]  E. P. Grimsrud,et al.  Detection mass bias in atmospheric pressure ionization mass spectrometry , 1991, Journal of the American Society for Mass Spectrometry.