Coelutions using one dimensional chromatography are often observed in flavour and fragrance analysis. There are several approaches to resolve these problematic regions.

What is heart-cut MDGC about? A problematic section of the chromatogram is cut and transferred into a second column, which can be mounted in a second gas chromatograph (GC). Both GCs are connected with a heated transfer line. In the first dimension a flame ionization detector (FID) is normally used as the detector that is suited to an area normalization report. However, in finding coelutions in the first dimension it is very helpful to have an identification in the first dimension as well. This was recently realized by an additional deactivated capillary that splits a part of the effluent going to the FID and leading it into the mass spectrometer of the second dimension. With this kind of analysis chiral separation is often needed frequently as only one enantiomer has some influence on the human body. The regions of interest inside the first dimensional chromatogram can then be transferred by easy heart cuts with simple mouse clicks that define the times for cutting. The retention times of the uncut peaks that elute at retention times behind the cuts remain unchanged in the MDGC-2010 system without using any pressure corrections of retention times. This can be used by the recently described Multi-Deans Switch technology.

In contrast, comprehensive GC×GC(qMS) allows a one shot separation of complex mixtures (no enantiomeric separation). While in MDGC the total peak capacity is a sum of both columns N1 (1st dim) + N2 (2nd dim) in comprehensive GC×GC it is the multiplication N1∙N2 of both. In the latter, an orthogonal set of columns is usually used [i.e., a classical unpolar (polar) column is connected to a polar (unpolar) narrow bore column of about 1 m in length]. There are several modulation technologies available that can be grouped into thermal and flow modulation. For the latter, typical peak column flows of 10–20 mL/min are used and are, therefore, not as suitable for quadrupole MS detection, particularly because the flow dilutes the sample. As a result the sensitivity is drastically reduced. In this instance, thermal modulation with quadrupole detection was used.

Articles

Regular Article

Coelutions using one dimensional chromatography are often observed in flavour and fragrance analysis.

Profiling Flavours and Fragrances by Heart-cut MDGC(MS) and Comprehensive GCxGC(qMS) in One System

In February this year China announced intensified efforts to ensure safer food, after melamine-tainted milk products from the 2008 scandal in which six babies died and 300 000 babies fell ill, re-emerged in several stores around the country.

This tragedy brought the issue of food safety under the world spotlight. The World Health Organization (WHO) has stated that foodborne diseases and threats to food safety constitute a growing public health problem. Unsafe food is the cause of many acute and lifelong diseases, ranging from diarrhoeal diseases to various forms of cancer. WHO estimates that foodborne and waterborne diarrhoeal diseases taken together kill about 2.2 million people annually, 1.9 million of them children.

Many world governments, particularly those in developed countries, have established dedicated bodies to develop, monitor and enforce food safety directives and regulations.

The EU parliament is informed on food safety matters by the European Food Safety Authority (EFSA). In the US, the Food and Drug Administration (FDA) publishes the Stephen Harrison and Katrin Åkerlindh, Linde AG, Pullach, Germany. Food Code, a model set of guidelines and procedures that assists food control jurisdictions by providing a scientifically sound technical and legal basis for regulating the retail and food service industries, including restaurants, grocery stores and institutional foodservice providers such as nursing homes.

In recent years, the Chinese government attempted to consolidate food regulation with the formation of the State Food and Drug Administration of China in 2003 and, following the 2008 tainted milk scandal, officials have come under intense public and international pressure to solve food safety problems. However, it appears that these regulations are not well known by the trade. Labels used for “green” food, “organic” food and “pollution-free” food are not well recognized by traders and many are unclear about their meaning.

Some of the threats to food safety and the measures in place for protection are discussed

Sophisticated Measures to Ensure Food Safety and Integrity

PerkinElmer has announced that its technology can be used to ensure the safety of traditional Chinese herbal medicines. In a recent collaboration with the Chinese food and drug institute the company has shown that its inductively coupled plasma mass spectrometer (ICP-MS) technology can be used to monitor the inorganic impurities within these remedies. This collaboration came about amid concerns that herbal ingredients may contain potentially toxic contaminants. 

Traditional Chinese herbal medicines (TCHMs) have been used for many years but in recent times have been modernized by transforming the plants and ingredients to solutions, soluble granules and tablets. These types of medicines are used worldwide and as such are grown in varying types of soils and conditions, which means that there are biological variations giving rise to the need for safety, efficacy and quality evaluations.

From 1 July 2010, the Chinese Pharmacopoeia 2010 (CP) will take effect with an important update setting out limitations on five elements (Cu, As, Cd, Hg and Pb) for all venous herbal injections and some medicinal plants. In an application note available from the company, the ELAN ICP-MS instruments were used for the routine quantification of inorganic impurities in TCHM. It was demonstrated that the instruments were capable of establishing method detection limits for the five elements that were low enough to analyse and evaluate samples of TCHM so that the requirements of the CP were met.

More information on the products mentioned in this story or a copy of the application note are available from PerkinElmer’s website at 

News

PerkinElmer has announced that its technology can be used to ensure the safety of traditional Chinese herbal medicines.

Hoorah for herbal

 It has been revealed that the collaboration between Thermo Fisher Scientific’s Biomarker Research Initiatives in Mass Spectrometry (BRIMS) Center and three organizations will be extended.

Over the last couple of years, the BRIMS Center, George Mason University’s Center for Applied Proteomics and Molecular Medicine (CAPMM), Johns Hopkins University and Toronto’s University Health Network (UHN) have collaborated to speed up protein biomarker identification for cancer and other diseases. The results of this collaboration were recently demonstrated at the US Human Proteome Organization 2010 meeting in Denver, Colorado, USA.

To address the challenges set out by biomarker researchers seeking to independently validate hypothetical biomarkers and routine mass spectrometry-based quantitative assays suited for clinical research, the BRIMS Center developed targeted SRM-based quantitative mass spectrometry workflows that allow rapid assay development and cross validation of biomarker assays across the network of laboratories. Each of the collaborators uses these biomarkers and assays to perform research on identical Thermo Scientific TSQ Quantum Ultra triple quadrupole mass spectrometry platforms.

The director of the BRIMS Center, Mary Lopez, stated, “Working together, the BRIMS Center and the collaborators demonstrated an instrument platform and an end-to-end workflow from sample preparation through data analysis that are easily and reproducibly transferred from laboratory to laboratory. By continuing our work with these leading research groups, we can extend their ground-breaking research by continuing to apply the SRM-based workflow to previously validated clinical biomarkers.”

This study is reportedly the first inter-lab study to demonstrate reproducible determination of protein abundance in a complex matrix such as blood.

For more information visit Thermo’s website at 

It has been revealed that the collaboration between Thermo Fisher Scientific?s Biomarker Research Initiatives in Mass Spectrometry (BRIMS) Center and three organizations will be extended.

Collaboration extension

The chemical composition of amber depends on a number of factors. Often mistaken as a gemstone, amber is, in fact, the fossilized resin of trees such as firs and spruces and it’s the type of plant as well as the age of the sample and the conditions that it was created in and exposed to since then that play their part in its structure. The geographical and biological origins of amber jewellery and amber ornamentation can provide historians with information about the people who made and wore them. This is why hyphenation between thermal desorption (TD), gas chromatography and mass spectrometry detection has been employed by a team from Romania

 to find if it is possible to discriminate between Romanian and Baltic ambers, two closely related amber species.

A TD unit equipped with a hydrophobic trap collected the volatile compounds from the samples; these were then desorbed in splitless mode to a GC linked to a single quadrupole mass spectrometer operating in electron ionization mode. Chromatographic data analysis was based entirely on automated mass spectral deconvolution and identification system (AMDIS) software to produce deconvoluted mass spectra that were used to build up a mixed mass spectra and relative retention scale library. Analysing a set of known origin showed good discrimination between Romanian and Baltic samples and when the process was applied to five ambers of unknown origin, all were successfully shown to fit into one of the two groups.

 M. Vîrgolici et al., J. Chromatogr. A, 1217(12), 1977–1987 (2010).

Hyphenation between thermal desorption (TD), gas chromatography and mass spectrometry detection has been employed by a team from Romania to find if it is possible to discriminate between Romanian and Baltic ambers, two closely related amber species.

A fine amber line

Agilent Technologies has released a statement reporting that its portfolio of DNA microarrays is now manufactured under ISO 13485 certification, a recognized standard for quality management systems (QMS).

Robert Schueren, Agilent vice president and general manager, Genomics and Life Science Reagents, commented, “Agilent has always emphasized quality in the manufacture of microarrays and we’re very pleased to be adding the validation of ISO 13485-registered QMS on top of our existing ISO 9001 standard.”

Additionally, the company is preparing to take the next step in pursuing clearance from the US FDA for a cytogenetics platform, according to vice president and general manager of the Biological Systems division, Gustavo Salem.

For more information on the company and its products visit the website at 

QMS compliance achieved

Innovation plus education and networking is the best equation to describe Pittcon 2010. Pittcon has always served as a showcase for innovations in laboratory science, as well as provided the perfect venue for leading scientists to share their latest research and findings... and this year is no exception. The Pittcon 2010 technical programme offered a diverse educational component with more than 2200 technical papers included in symposia, contributed and oral sessions, workshops, awards and poster sessions. New for this year, registered attendees received access to webcasts of 50 select technical presentations for 60 days following the show. Attendees were also able to continue their education by taking one or more of the very affordable short courses designed to provide training in new technologies, continuing education and improving career skills.

Pittcon has always served as a showcase for innovations in laboratory science, as well as provided the perfect venue for leading scientists to share their latest research and findings... and this year is no exception.

(Innovation)2 + (Education)2 × Networking = Pittcon 2010

I was lucky enough to visit Pittcon again this year, in sunny (but unseasonably cold) Orlando, Florida, USA. There were several highlights to the show this year, some of which included (in no particular order):

All of these new developments or twists on older technologies are encouraging and I can see utility for several of them in my own applications. I have posted a thread into the 'Off Topic' Forum of the 

 site The CHROMmunity with links and further information on my Pittcon highlights. I would encourage you to read if you didn't get to the show and post a reply if you did, to give our colleagues the benefit of your attendance and your opinion!

There was, however, a more disappointing aspect to the show that appeared especially in the poster sessions but also in some of the oral sessions. As I travelled the miles of poster boards and sat through the various lectures, it became apparent that many of us still don't know how to choose or optimize buffers for liquid phase separations.

As I travelled the miles of poster boards and sat through the various lectures, it became apparent that many of us still don?t know how to choose or optimize buffers for liquid phase separations.

The Column-04-23-2010