Hyphenated approaches to analysis have received much attention over the last three decades to the extent that techniques such as GC–MS, GC–FTIR and LC–MS have – in the relevant fields – become indispensable parts of the analyst’s arsenal. This concept has been extended to include multi-hyphenated techniques, where the chromatography is preceded by analyte extraction from a sample matrix. In the field of GC–MS, examples include thermal, sorptive or headspace extraction, with subsequent preconcentration, for instance, by thermal desorption (TD).

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Hyphenated approaches to analysis have received much attention over the last three decades to the extent that techniques such as GC?MS, GC?FTIR and LC?MS have ? in the relevant fields ? become indispensable parts of the analyst?s arsenal. This concept has been extended to include multi-hyphenated techniques, where the chromatography is preceded by analyte extraction from a sample matrix. In the field of GC?MS, examples include thermal, sorptive or headspace extraction, with subsequent preconcentration, for instance, by thermal desorption (TD).

Harnessing the Power of Multi-Hyphenation in Food Flavour and Odour Analysis

A new method has been developed for the identification and classification of various tuberculosis (TB) causing and non-TB Mycobacterium species on the basis of their characteristic metabolite profiles.1

A modified Bligh-Dyer extraction procedure was used to extract lipid components from Mycobacterium tuberculosis, M. avium, M. bovis and M. kansasii cultures. Principle component analyses (PCA) were applied to the GC–MS generated data and showed a clear differentiation between all the species tested. The twelve compounds that best showed the variation between the sample groups were identified and classed as potential metabolite markers, using PCA and partial least-squares discriminant analysis (PLS–DA). These markers were then used to build a Bayesian statistical classification model. The model identified 2 ‘unknown’ samples for each of the Mycobacterium species analysed, with probabilities ranging from 72–100%.

The test had the advantage of speed and could be performed in under 16 h. The detection limit was 1 × 103 bacteria mL21.

The study concluded that there was potential for a GC–MS, metabolomics pattern recognition approach to be used in TB diagnosis.

1. D. Toots et al., Journal of Microbiological Methods, 88(3), 419–426 (2012).

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A new method has been developed for the identification and classification of various tuberculosis (TB) causing and non-TB Mycobacterium species on the basis of their characteristic metabolite profiles

TB detection

Prostate cancer is the most common cancer in men in western countries and is on the rise again.

An article published in 2008 determined that capillary electrophoresis mass spectrometry urinary proteome analysis was very accurate in detecting prostate cancer. The same research team has now applied this test in clinical practice and its cost-effectiveness.1

The urinary proteome analysis test was performed on 211 outpatients who had been referred to with suspicious prostate-specific antigen or after digital rectal examination. In 184 data about their follow up and the test results were available for analysis. Prostate cancer was detected by biopsy in 49 cases. The test correctly recognized 42 out of 49 cases, which is a sensitivity of 86%. Out of 135 prostate cancer-negative patients, 79 had a negative response in the urinary proteome analysis, a specificity of 59%. Negative and positive predictive values were 92% and 43%, respectively. In addition, the urinary proteome analysis results agreed in 65.7% of the follow-up reference results.

The team also analysed how cost-effective the procedure was and they concluded that their method was more beneficial than the biopsy approach as fewer biopsies were performed and fewer complications arose as a result.This procedure has many benefits for the patient, including its non‑invasive nature, and it was concluded that the test is a helpful addition to prostate cancer diagnostics.

1. W. Schöfer et al, International Journal of Urology, 19(2), 118–125 (2012).

Improved analysis

The consumption of beer is, for some, one of life’s great pleasures but it can leave behind a bitter aftertaste.

A team of researchers in Austria and Germany has undertaken a study that has revealed that the bitter acids in hops stimulate gastric acid secretion.1 The team compared the effects of five different beers on mechanisms of gastric acid secretion. Organic acids and bitter compounds were quantified by HPLC–DAD and UPLC–MS–MS and tested in human gastric cancer cells (HGT-1). This was performed using a pH-sensitive fluorescent dye that determines the intracellular pH and would indicate proton secretion. They also measured the expression of four genes, coding the H+/K+-ATPase, ATP4A, the histamine receptor, HRH2, the acetylcholine receptor, CHRM3, and the somatostatin receptor, SSTR2, by quantitative polymerase chain reaction (qPCR).

Ethanol and the organic acids succinic acid, malic acid and citric acid contributed to some extent to the effect of beer. The bitter acids, α-, ß- and iso-α-acids, were identified as potential components promoting gastric acid secretion. They also promoted up-regulation of CHRM3 gene expression by a maximum factor of 2.01 compared with that of untreated control cells with a correlation to their respective bitterness.

The potential is, therefore, present for brewers to produce beers that do not generate gastric acids in a large quantity.

1. Veronika Somoza et al., J. Agric, Food Chem., 60(6), 1405–1412 (2012).

The consumption of beer is, for some, one of life?s great pleasures but it can leave behind a bitter aftertaste.

Gassy acids

A group of scientists in France have undertaken a study to examine the structure of proteins in human hair.1

Hair is subjected to a variety of treatments during its growth and these can cause irreversible damage. Studying the structure of hair proteins can be challenging due to their physiochemical properties so the team used two complementary approaches to solve this issue.

The multidimensional protein identification technology (MudPit) approach allowed the team to identify eight of the nine type I keratins and five of the six type II keratins, as well as the major KAPs. Posttranslational modifications in keratins, including cysteine trioxidation, lysine and histidine methylation, were also identified.

Two-dimensional gel electrophoresis coupled with MS was able to provide a complete 2D gel pattern of human hair proteins. Cleaved species in hair keratins were found. Where these broken proteins have come from is not clear but the results indicate a preferential breaking zone in α−helical segments. These fragmented proteins were also only observable following gel separation, which highlights the importance of the two complementary proteomics approaches.

1. N. Cavusoglu et al., Analytical Biochemisty, 421, 43–55 (2012).

A group of scientists in France have undertaken a study to examine the structure of proteins in human hair.

The Column-03-21-2012

Harnessing the Power of Multi-Hyphenation in Food Flavour and Odour Analysis

TB detection

Improved analysis

Gassy acids

Hair care