LC–MS

Mass spectrometry has long been a preferred tool for protein identification and biomarker discovery, but preparation of biological samples remains a challenge. Hindrances include the wide range of protein concentrations, sample complexity, and loss or alteration of important proteins due to sample handling. This article describes recent developments in sample fractionation technologies that are overcoming these challenges in interesting ways and are enabling in-depth proteomic studies that were not possible in the past.

Doping testing is now an accepted fact of sporting life - whether in major international competitions, such as the Olympics, or in regular events at the national level. Athletes who cheat by taking banned substances risk harming their careers and their health. They also bring their country and their sport into disrepute. A reliable and reproducible scientific system for doping testing, backed up by sanctions, helps fight the culture of drugs in sport so that athletes can participate on a level playing field.

September 2006. Top-down and bottom-up are alternative strategies for protein identification and characterization by mass spectrometry. How do they fit into the world of proteomics? What are their implications for separation technology? These questions are addressed in this installment of "Directions in Discovery."

In Part I of this two-part look at spectral interpretation, Michael Balogh examined the ability to see and appreciate the product of our analytical devices. In Part II, he takes a closer look at the tools of the trade.

Midazolam is a central nervous system depressant that is commonly used as a sedative before surgical or other medical procedures.

In this column, Michael Balogh proposes some practices that you can adopt to enhance your prospects of being right when converting data to knowable information and applying it to solving problems.

In this tutorial, the mechanism and origin of ion suppression will be investigated, as well as ways to validate the presence, and circumvent or compensate for, the effects in LC-MS.

This is the second installment of a two-part series on the practical aspects of configuring and operating a nano liquid chromatography-mass spectrometry (LC-MS) system.

This month's column explores the idea that despite the well-considered physics and engineering involved in mass spectrometer technology, it nonetheless seems that the uality of one's results are as much the product of art as they are of science.

Definitions, however meticulously crafted, can give the meaning of terms with scrupulous clarity, but often fail to tell us how to apply them. Such definitions are descriptions that dictate usage but stop well short of the sense and purpose that many of us turn to them for.

Few areas of LC-MS practice have been so affected by geopolitics as that of food safety analysis, a topic as important as it is complex. here, Michael Balogh examines this topic.

The use of a simple Excel-based "Golf Score Card" tool can facilitate assessments and instrument acquisistion decisions by collating and weighting the relative importance of the many criteria that impact the final purchase decision. The authors describe this process.

Columnist Michael Balogh explores the topics of informatics and data management with this month's featured scientists.

As LC-UV and LC-MS have become preferred instrumental methods for fast, sensitive analysis, many scientists are searching for ways to optimize performance.

Co-occurrence of several mycotoxins (deoxynivalenol, zearalenone, T-2-toxin, HT-2 toxin) produced by field fungi, such as Fusarium graminearum and Fusarium culmorum, requires several analysis methods for their characterization. A reliable method for the determination of type A- and B-trichothecenes and zearalenone in cereal-based samples is presented. To achieve optimal mass spectrometric detection, electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) were compared. Best results were obtained with ESI by implementing a two-period switching for the ionization polarity. The limit of quantification differs for each individual substance within the range 1–10 ppb. Mean recoveries using a standardized clean-up procedure were in the 54–93% range.

In this initial installment of "MS - The Practical Art," a new series of columns is introduced that investigates various aspects of mass spectrometry (MS) from the perspective of some leading practitioners. Here, featured scientists Kathleen Cox and Timothy Baker discuss several MS technologies and strategies currently being applied to characterize drug candidates in early stage development.

The separation of individual congeners of commonly used fluorescent whitening agents is described.

Increase efficiency, not frustration, in small-molecule practices.

"A well-prepared sample, a well-defined analytical goal, the appropriate use of accurate mass, reproducible retention times, and good instrument control generate unassailable data..."

Wehr discusses strategies for coupling LC and CE with MALDI–MS for use in proteomic studies.

Tim Wehr looks at the use of fast LC}MS for high-throughput analysis of pharmaceutical compounds.

What is the baseline telling us?

The authors investigated the analytical capabilities of quadrupole, time-of-flight, and Fourier transform mass analyzers for liquid chromatography electrospray mass spectrometry (LC-MS) applications.

This month's "Directions in Discovery" gives a brief overview of turbulent- flow liquid chromatography, a technique for fast separations. Two examples demonstrate the use of the technology for high-throughput bioanalytical separations in drug discovery.

The authors investigated the two most popular types of interfaces for benchtop LC–MS systems – the particle interface and the atmospheric-pressure ionization interface – to learn how the information obtained separately from the two can be complementary.

Despite their different levels of technological maturity, CE and LC coupled with electrospray ionization MS techniques can be operated at the same level of automation. However, they differ in their configuration, selectivity, sensitivity, and method development.

Current sample preparation procedures for LC–MS as applied to samples from biological matrices.