A Banner Year for New Mass Spec Titles

This year was the best year to date for sales of mass spectrometry titles at the ASMS meeting in Seattle. Seventeen new books (less than 18 months old were on our title list, including two of our own from Global View Publishing. Clearly, the beneficiary is the reading audience in that many important topics are being made available to meet changes and demands in the mass spec market.

We are proud to announce the publication of David Sparkman's second edition of "Mass Spectrometry Desk Reference" which has become the de facto standard for language and reference information in mass spectrometry. A second title from Global View is "LC/MS Methods: an essential tool to accelerate methods development" by Steve Down and John Halket. This CD-ROM data base of over 15,000 abstracted and indexed methods allows time-saving searching for method protocols and method parameters.

A number of noteworthy new titles are listed and discussed in our new monthly column entitled Publisher's Corner. Each month we will discuss current and future topics relating to publishing in mass spectrometry.

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How Do We Eliminate Ion Losses at AP?

Keeping the Barn Doors Open

Study Sphere Excellence Award for LC/MS Homepage

Check out our website, it has recently undergone some renovations to help enhance the look and streamline your interaction. We are very honored to receive the Study Sphere Award of Excellence (Seal Above) for our educational site. Please take a look around and enjoy the new content and graphics. Each month we will include Feature Articles to address topics of interest to the LC/MS community and Publishers Corner to keep you up-to-date with new and future titles.

Four Chem-Space Patents Issue This Summer

Our goal to develop key technologies to facilitate the growth of LC/MS is headed in a positive direction with the issuance of our 18th patent this summer. We have concentrated on the development of source, optics, and ion transmission technologies.

Click patent front page to obtain *.pdf version.

Where Losses Occur

Did you know that typical atmospheric pressure (AP) ionization sources detect only about one-in-ten thousand ions generated at atmospheric pressure? In addition, most of the ions are deposited on the walls of the source and along the conductance pathway before getting into vacuum? Sources generate currents from 100s of nAmps with electrospray to 10s of uAmps with APCI, but the best sources conduct only a few nAmps into vacuum. Ion guides (1) and funnels (2) have been developed to efficiently transmit ions through successive vacuum stages for analysis and detection, but are ineffective at transmitting ions that are lost at AP.

This is a classis example of the old metaphor “…closing the barn door after the cows have escaped.” The challenge for improving LC/MS and related techniques using AP sources is to prevent ions from being lost on the walls of the source and on the walls of the conductance pathway. This has been the primary objective in our lab for over a decade.

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What are our alternatives?

To address the significant ion loss at atmospheric pressure, we must evaluate where and how ions are lost. The inherent dispersive nature of spray and electro- hydrodynamic sources makes sampling ions through a typical cross-section of several hundreds of microns in diameter problematic. Even highly directed sprays from precision nebulizers will produce spray cross-sections of over a centimeter in diameter.

Historically, we have paid the least attention to the conductance opening region where most of the ions are lost. We have been limited to vain attempts to focus ions through small cross-section pinhole apertures or tubes. The more we focus at AP, the smaller becomes our effective ion transmission aperture. The less we focus the larger the effective conductance aperture. This concept of effective ion transmission aperture is illustrated in Figure 1.

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