The use of MS in the chemical analysis field is ubiquitous and its power to provide valuable molecular structural information is unsurpassed. However, the techniques which make up the MS family are complex and application and best practice is sometimes a difficult challenge. Produced in association with world renowned Prof. David Sparkman and Dr Fred Klink, MS Solutions is the leading platform for fundamentals, applications and troubleshooting of mass spectrometry.
    		                           
    Determination of Intact Protein Molecular Mass
    by Frederick Klink
    from Multiple-Charge Electrospray Mass Spectra
    In two previous instalments of MS Solutions, I discussed the
    sequencing of simple, single-charge peptide ions using
    MS/MS. In this and another upcoming edition I am going to discuss
    the use of multiple-charge ions in protein and peptide analysis.

    NIST 11: What’s New and What Value Does it Offer? Part 5
    Structural Identification of Unknowns from Spectra Obtained Using LC/MS and CAD Techniques and EI Mass Spectral Database
    by O. David Sparkman
    This is the last in the five-part series about the features of NIST 11. This instalment shows how spectra obtained by MS/MS methods from various soft ionization techniques, including those used with LC/MS can be searched against the NIST/EPA/NIH EI Mass Spectral Database and the results used to facilitate a structure determination.


    NIST 11: What’s New and What Value Does it Offer? Part 4
    by O. David Sparkman 
    This instalment in the series on NIST 11 is about the Incremental Name Search, replicate spectra, and the NIST GC Methods, and Retention Index Database.
     
     
    NIST 11: What’s New and What Value Does it Offer? Part 3
    by O. David Sparkman
    The previous two instalments provided information on the NIST/EPA/NIH Mass Spectral Database, past and present, and on the use of the NIST MS Search Program in identifying a compound from its mass spectrum using both the NIST EI Database and the NIST Database of spectra obtained using MS/MS techniques. In Part 3, the use of the searches in the Other Search tab view is examined. These searches can be beneficial to the identity of compounds from mass spectra obtained by ionization techniques other than EI and from data that provides a higher accuracy of the measure m/z value than is usually available for EI data    .
     
     
    NIST: What’s New and What Value Does it Offer? Part 2
    By O. David Sparkman
    The NIST 11 Mass Spectral database, the successor to the NIST 08, is a fully evaluated collection of electron ionization (EI) Mass Spectra, which also includes a growing number of MS/MS Spectra and GC data. In this multi-part article, David Sparkman looks at history and current status of NIST 11 and explains its value to analytical scientists.
     
    NIST: What’s New and What Value Does it Offer? Part 1
    By O. David Sparkman
    The NIST 11 Mass Spectral Database, the successor to the NIST 08, is a fully evaluated collection of electron ionization (EI) Mass Spectra, which also includes a growing number of MS/MS Spectra and GC data. In this multi-part article, David Sparkman looks at history and current status of NIST 11 and explains its value to analytical scientists.
     
    Peptide Sequencing with Electrospray LC/MS Part 2: Interpretation of a Simple Spectrum
    By Frederick Klink
    In last month’s MS Solutions we discussed MS/MS fragmentation of polypeptides, the types of ions formed, and the mechanism of their formation. This month we will examine a tandem mass spectrum of a simple polypeptide and step through an interpretation strategy leading to the complete sequence determination.
    Click here for the full article >> 
     
     
    Peptide Sequencing with Electrospray LC/MS Part 1: Ion Types and Nomenclature
    By Frederick Klink
    One of the most significant and important applications for mass spectrometry is the sequencing of polypeptides by electrospray LC/MS. An error in the sequence or the substitution of one amino acid with another can completely alter the biological function of a peptide molecule. Determination of sequences is therefore a vital part of biomedical research, proteomics, and the manufacture of peptide-based drug substances. We will discuss the basics of peptide sequencing with mass spectrometry in the next three issues of MS Solutions.
    Click here for the full article >>   

     
    Confusion Resulting from Molecular Weight and the Nominal Mass, Monoisotopic Mass, and Average Molar Mass
    By O. David Sparkman
    Mass associated with chemical formulae is diff erent for those working in mass spectrometry as compared to those working in other fi elds of chemistry and in physics.
     

    Adjusting Electrospray Voltage for Optimum Results
    By Frederick Klink
    An electrospray LC/MS interface consists of an enclosed, atmospheric pressure chamber. The HPLC efluent enters this chamber through a capillary tube which is surrounded by a second, concentric tube through which a nebulizing gas is applied. In this article I will refer to this assembly as the LC capillary. Opposite from or, in modern designs, orthogonal to the incoming HPLC efluent is the inlet to the mass spectrometer. This inlet is usually a capillary tube as well and will be referred to hereafter as the MS inlet.
    Click here for the full article >> 
     

    The Role of Isotope Peak Intensities Obtained Using Mass Spectrometry in Determining an Elemental Composition, Part 2
    By O. David Sparkman
    An Illustrative Example of the Use of Isotope Peak Ratios to Determine an Elemental Composition taken with permission from Chapter 5 of Introduction to Mass Spectrometry: Instrumentation, Applications and Strategies for Data Interpretation, 4th Ed., Wiley: Chichester, UK, 2007 by J. Throck Watson and O. David Sparkman.
    Click here for the full article >>  
     

    The Role of Isotope Peak Intensities Obtained Using Mass Spectrometry in Determining an Elemental Composition, Part 1
    By O. David Sparkman
    The atomic mass of an element is the weighted average of the masses of the naturally occurring isotopes of that element. These different isotopes of an element have different masses that are almost an integer in value because of diff erent numbers of neutrons in their nuclei; e.g., carbon has two primary naturally occurring isotopes, 12C and 13C. These two isotopes have respective integer masses of 12 and 13. Atoms of 12C have one less neutron in their nuclei than do atoms of 13C. This means that a mass spectrum of an ion containing carbon will be represented by peaks that are one m/z unit apart. The lowest m/z value peak represents an ion where all the carbon atoms are 12C. The peak one integer m/z value higher represents an ion where one of the carbon atoms is 13C. The peak one m/z unit higher than that represents the ion where two of the carbon atoms are 13C and so on.
     

    Dealing with Metal Adduct Ions in Electrospray: Part 2
    By Frederick Klink
    Last month we discussed the fundamental issue of metal adduct ion formation in electrospray LC/MS including method development strategies for dealing with adduct ions. This month we will examine a real-world application which employs these strategies.A few years ago our laboratory developed a method for penicillin G by electrospray LC/MS.
     

    Dealing with Metal Adduct Ions in Electrospray: Part 1
    By Frederick Klink
    The term “adduct ion” is a popular term among liquid chromatography/mass spectrometry (LC/MS) users to describe ions formed by adduction of alkali metal ions to an analyte molecule in positive ion analysis. However, the well-informed user should be aware that “adduct ion” correctly refers to any ion formed by adduction of an ionic species to a molecule. Therefore, the common protonated molecule or [M+H]+ is also properly called an adduct ion. In our column this month we will be discussing specifi cally the adduction of alkali metal ions (Na, K), to analyte molecules and will therefore use the term “metal adduct ion” to refer to these species.
     

    Improving Electrospray LODs by Decreasing Column Diameter
    By Frederick Klink
    Reducing the internal diameter of your HPLC columns is an advantage for electrospray (ESI) LC/MS users. To understand this, two characteristics of ESI must be understood: (1) how response (i.e., peak area or height), is related to analyte concentration and (2) how response varies with HPLC flow rate.
     

    Quantitation in hyphenated chromatographic techniques
    By Frederick Klink
    Mass spectrometry has long been a valuable quantitative tool used across many industries for numerous applications including food [1], beverage [2], pharma [3] and environmental analysis [4]. Its utility ranges from use as an alternative detector to UV in LC for difficult non-chromophoric analytes to those applications that fully exploit the extra resolving power or sensitivity that mass spectrometry can afford.
     
    FEATURED MS WORKSHOP

    LC/MS: Fundamentals and Applications
    June 5-6, 2012 
    Basel, Switzerland
    LC/MS: Fundamentals and Applications is a comprehensive overview course that provides attendees with relevant, practical approaches that can be immediately applied in the lab. The theory of LC/MS interfaces (electrospray, atmospheric pressure chemical ionization, and atmospheric pressure photoionization), is presented to the extent necessary to understand operation of these instruments but the real focus of this class is improving your ability to use LC/MS on a daily basis. This course is offered as a three-day workshop.
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    Mass Spectral Interpretation
    June 7-8, 2012
    Basel, Switzerland
    The training course on interpretation of mass spectra is designed to develop the fundamental skills necessary to understand fragmentation of ions formed by electron ionization (EI) in GC/MS or by one of the soft ionization techniques employed in LC/MS. Many of the examples are taken from EI mass spectrometry; however, the principles that are learned are applicable to any ionization technique.
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