Technology Forum: LC–MS

The high sensitivity and specificity of LC–MS makes it a powerful technique suited to many applications ranging from pharmacokinetics and proteomics to forensics and food safety. With the development of new LC–MS methods to analyse increasingly difficult samples, the expansion into new application areas has become a possibility.

Janet Kelsey, Electronic Editor, LCGC Europe approached three experts in LC–MS and asked them for their thoughts on the current status of the technique and how they perceive its future. Joining us for this forum are Michael McGinley of Phenomenex; Mary Ellen Goffredo of Waters Corporation and Martin Hornshaw of Thermo Fisher Scientific.

What are the current trends in LC–MS?

McGinley: High speed and high throughput continue to remain key performance parameters in LC–MS development. MS instrumentation continues to increase in speed and sensitivity to meet performance gains realized by next generation HPLC column technologies. Many MS vendors have recently been expanding their system integration tools as well as introducing generic method development databases for popular LC–MS methods.

Goffredo: The evolution of LC–MS is enabling a change in analytical workflow from a simple question of "is a particular compound present in a given sample" to a more complex investigation of "what are the compounds in my sample and how much is present for each compound." A great example is food safety analysis where the number of different potential pesticide contaminants extends into the thousands. This evolving analytical capability means today’s LC–MS systems are attracting a more diverse user base than ever. Compared to lab scientists who dedicated their careers to fine-tuning these instruments, today’s LC–MS operators have a more varied background, which means both system operation and data interpretation software need to be simplified in order to produce a meaningful analysis.

Hornshaw: The most compelling recent trend in mass spectrometry is towards increased performance in terms of mass accuracy and mass resolution on an easy-to-use platform. Thermo Fisher Scientific developed the LTQ FT, providing access to FT-ICR performance, in a hybrid format, coupled to ease-of-use. Only a couple of years later the Thermo Scientific LTQ Orbitrap was launched in 2005, another type of FT instrument, providing high resolution and mass accuracy with improved sensitivity, at a lower price point with even greater ease-of-use and robustness. Following that challenge, QTOF performance has improved with instruments achieving approximately 40,000 FWHM resolution, which is still far off the LTQ FT or LTQ Orbitrap performance. Owing to the clear benefits of high resolution and mass accuracy towards unambiguous compound identification, this trend will continue.

Another significant trend is towards increased speed of data acquisition. Recently developed QTOF instruments achieve speeds up to 20 Hz, although owing to the nature of QTOF mass spectrometers, increased speed of acquisition leads to decreased sensitivity. The LTQ Orbitrap is a hybrid FTMS consisting of two different types of mass analysers; the linear ion trap and the Orbitrap, therefore increased speed of data acquisition does not result in a decrease in sensitivity. LTQ Orbitrap mass spectrometers are mostly applied to research environments. For example, they are very popular with scientists working in the fields of proteomics, metabolomics, biomarker research or drug discovery. The latest generation of LTQ Orbitrap, the Thermo Scientific LTQ Orbitrap Velos, launched at ASMS in 2009, has achieved a ‘proteomics speed’ of approximately ‘1000 protein identifications/per hour’.

The last trend I wish to discuss is the increasing need and demand for ‘integrated solutions’. By this I mean that the customer wants not just a good mass spectrometer but also everything before and after the instrument. The customer wants to see a seamless flow of data and information from the start point of sample storage and preparation all the way through to the results and conclusions of the analysis. In some applied markets particularly this is becoming or already is a must-have.

What is the LC–MS application area that you see growing the fastest?

McGinley:Environmental and food safety are probably the topic areas where we see the most “new” interest in LC–MS. Environmental testing laboratories have been starting to move some GC–MS assays to LC–MS to take advantage of the improved sensitivity and throughput that such a method offers. In the food safety arena several very public scares with melamine in China and Sudan dyes from India have led to a public outcry for more food testing by manufacturers and regulatory agencies alike.

Goffredo:With the overall demand for LC–MS growing, there are two areas in particular that are growing faster than most: food safety testing and biopharmaceutical applications. Growth in food safety testing is being fuelled by a rapidly globalized food chain coupled with high-profile food contamination incidents. Additionally, as the pharmaceutical industry continues to shift focus and investment to large-molecule compounds, biopharmaceutical laboratories are turning to LC–MS to address challenging applications, such as peptide and protein characterization.

Hornshaw:The clear current trend in mass spectrometry is towards the application of these powerful analytical devices to more applied settings. These are primarily environmental, food safety and clinical research or forensic/toxicology analyses. This more routine type of mass analysis, one might call them ‘mass spec assays’, is typically performed by triple quadrupole mass spectrometers. However, again, mass spectrometers with high mass accuracy and resolution such as the benchtop mass spectrometer, the Thermo Scientific Exactive, based on Orbitrap technology, are starting to be used in these applied areas and show much potential to improve productivity since they need little or no method development to produce a mass spectral assay and can also be used to detect and quantify both known and unknown compounds simultaneously.

What obstacles stand in the way of LC–MS development?

McGinley:Addressing sample preparation issues for analytes in biological matrices remains the most difficult challenge in LC–MS method development. Biological sample sources such as plasma, urine and tissue samples contain complex mixtures of MS interfering compounds that must be removed from a sample to get MS detection and quantification of an analyte of interest. In addition, multiplexing such complex sample preparation methods adds an additional challenge for high throughput LC–MS methods. Another obstacle for developing sensitive LC–MS assays revolves around reducing background as well as removing any run-to-run carryover that may occur in an analysis method.

Goffredo:The only obstacle in the way of LC–MS development is imagination. We are constantly listening to what our customers identify as their most challenging problems. These issues can range from speed to usability to data management. Today’s LC–MS systems, including chemistry and informatics solutions, continue to evolve to more specifically address targeted applications.

Hornshaw: The rate of improvement in performance in mass spectrometry is astonishing, rather like the development seen in the 1990s in personal computer performance. In addition, liquid chromatography has advanced in recent years in leaps and bounds, although arguably not as quickly as for mass spectrometry. I expect this performance improvement to continue for the foreseeable future, especially in the area of high performing mass spectrometry instrumentation as exemplified by the Orbitrap mass analyser. The industry is healthy and highly competitive so I am bullish about mass spectrometry development continuing apace.

Do you expect any major developments in LC–MS to be presented at Pittcon 2010?

McGinley:The commercialization of core-shell media like Kinetex will be a big area of discussion at Pittcon this year. Obtaining ultra-high performance and high-throughput results on standard HPLC systems drastically changes LC–MS instrument requirements as labs no longer need speciality high-pressure HPLC systems to perform high throughput LC–MS applications.

Goffredo:Pittcon 2010 is Waters 50th anniversary and we plan to continue our proud tradition of showing new technology solutions at this great venue. Our flagship research-grade system, SYNAPT G2, will make its Pittcon debut. The second generation SYNAPT G2 platform combines QuanTof, a breakthrough quantitative Tof technology, and enhanced High Definition MS technologies to provide intuitive operation, application flexibility and a totally new level of performance. Additionally, Waters will be introducing its newest member of our UPLC family, the ACQUITY UPLC H-Class system incorporating the proven, robust and reliable performance of UPLC technology with the operational familiarity of traditional HPLC technology. Look for more in the LC–MS area from Waters at ASMS 2010.

Hornshaw:Perhaps, but I don’t think so.

What is the future of LC–MS?

McGinley:The sensitivity and speed of MS instrumentation has improved dramatically in the last few years to match HPLC developments in increasing speed and resolution. The next area of LC–MS method innovations will likely be focused on improvements in sample preparation technologies and techniques. Increased multiplexing of sample preparation and improving the removal of biological matrix contaminants are going to be crucial in improving the throughput and sensitivity of LC–MS methods.

Goffredo:The future of LC–MS is focused on expanding the applications and user base so that more industries will benefit from this powerful analytical tool. To accomplish this goal, Waters will incorporate our award-winning Engineered Simplicity designs throughout our MS products thereby providing a wider range of users increased confidence in their analysis and data interpretation. Secondly, Waters is focused on continued performance improvements, especially for targeted application areas, such as biopharmaceutical, clinical and food safety applications.

Hornshaw: In a word – growth. Mass spectrometry sales per annum are already measured in the billions of dollars. Thus mass spectrometry is widely applied to solve analytical challenges. In terms of application we will see mass spectrometers applied to help solve every analytical challenge out there. Currently they are utilized, although for some of these applications it is certainly early days, in many areas. A sampling of these applications is pure and translational research in, for example, proteomics, metabolomics, lipidomics and biomarker research, and more applied areas such as therapeutic drug monitoring, toxicology, both clinical research and forensic analysis, water safety, food safety, pharmaceutical discovery and development and many more. However, this is still the tip of the iceberg. The power of modern mass spectrometry is exceptional and will continue to increase dramatically for the foreseeable future.

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