Put technically, breath malodour is an important negative factor in social communication. Volatile sulphur compounds (VSCs) are considered to be important contributors to bad breath and, therefore, are suitable biomarkers for breath quality evaluation. Morning breath gives a good indication as to the efficacy of treatments, but few studies have attempted to measure VSC levels directly after waking, instead inviting subjects into the laboratory at a fixed time in the morning. To gain deeper insight into morning breath, researchers developed a procedure to collect breath samples at home.

Subjects placed a syringe between their lips and maintained that position for 1 minute, then used the syringe to collect 10 mL of breath. Samples were taken directly after waking and shortly before and directly after breakfast. VOC levels in the samples were analysed later using a portable GC device.The results showed that VSC concentrations declined appreciably in the first hour after the subject woke up, disappearing after breakfast even without direct dental hygiene.

Surprisingly, the researchers found a significantly higher VSC concentration in the female population. Comparing this to previous studies suggests the effect may be limited to morning breath only. While the causes are unclear, the study does suggest that endogenous factors, such as salivary flow-rate, may play a role.

1. J. Snel et al., Arch. Oral Bio., 56(1), 29–34 (2011).

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To gain deeper insight into morning breath, researchers developed a procedure to collect breath samples at home.

Studying morning breath

 In 1976 the Viking landers took samples of the soil on Mars and analysed it for organic compounds. Traces were dismissed as contamination, however a reinterpretation of the results suggests significant levels were present, hidden by the strong oxidation effect of salt in the Martian soil.

In the Viking tests the landers heated the soil to vapourize organic compounds and the results were analysed by GC–MS. As well as small amounts of water and carbon dioxide, traces of chlorohydrocarbons were detected, but were dismissed. But in 2008, the Phoenix lander discovered perchlorates — powerful oxidizing compounds that combust organics — in the Martian Arctic soil. 

 took Mars-like soil from the Atacama Desert in Chile, which contained organic carbon, and mixed it with magnesium perchlorate. When heated, nearly all of the organics present were decomposed to water and carbon dioxide, but a small amount formed the same kinds of organic hydrocarbons detected in the Mars samples.

A chemical kinetic model was produced to predict the degree of oxidation and chlorination of organics in the Viking oven. Using the model to reinterpret the results suggests that samples from landing site 1 contained 1.5–6.5 ppm, while site 2 samples contained 0.7–2.6 ppm.

According to the study this discovery of organics will provide important information for future Mars missions looking to detect life itself.

1. R. Navarro-González, J. Geophys. Res., 115, E12010 (2010).

In 1976 the Viking landers took samples of the soil on Mars and analysed it for organic compounds. Traces were dismissed as contamination, however a reinterpretation of the results suggests significant levels were present, hidden by the strong oxidation effect of salt in the Martian soil.

Reanalysing Viking results

For years master gardeners have claimed that putting Bounce brand dryer sheets in their pockets repels pests, but no quantitative data had been obtained to substantiate these claims. However a study from Kansas State University, USA, has been able to provide definitive proof of the effect.

Fabric softener dryer sheets are added to dryers to control static cling and give clothes a fresh scent. They contain biodegradable cationic softeners and perfume. To test the sheets’ effectiveness at repelling insects, fungus gnats were released into an experimental area containing sample compartments, some with dryer sheet samples in, some without. This was repeated five times and in all five experiments, the mean proportion of fungus gnat adults collected in the sample compartments containing the dryer sheets were significantly fewer, ranging from 12–18%. 

To determine the causes of this effect the team also analysed the volatile compounds in the dryer sheets using GC–MS. One major compound detected was linalool, a colourless monoterpene alcohol used for its flower-like odour. Linalool is present naturally in plants such as lavender, marjoram and basil and has been shown to be toxic to a number of different mites and insects. High levels of the volatile compound beta‑citronellol were also detected. This compound is found in plants including rose geranium, citronella and lemon balm, and is known for its ability to repel mosquitos. The researchers conclude that in the future, the use of dryer sheets may be an alternative strategy to deal with fungus gnat populations in greenhouses.

1. R.A. Cloyd et al., HortScience, 45(12), 1830–1833 (2010).

For years master gardeners have claimed that putting Bounce brand dryer sheets in their pockets repels pests, but no quantitative data had been obtained to substantiate these claims.

Gnats off!

 A discovery during the investigation of subcritical water chromatography has led to a novel method that could provide a green and cheap addition to the analytical chemist’s toolbox. The research, published in 

 describes a method in which mixtures of carbon dioxide and water are used as both mobile and stationary phases, capable of performing separations on the inside of an uncoated capillary.

The researchers were experimenting with using subcritical water saturated with carbon dioxide as a mobile phase. They used a conventional packed column as a stationary phase and stainless steel tubing either side of the column. When they removed the column and flushed the system through they were surprised to find that separation was still occurring. They discovered that the water was forming a thin coating on the inside of the tubing and acting as a stationary phase. The researchers used this to determine a method using water saturated with CO

 saturated with water as a mobile phase. Analytes are separated based on how well they dissolve in water and CO

 — the more water-soluble elute later than those that are more soluble in CO

. This method uses only cheap and non-toxic chemicals, making it environmentally friendly and according to the researchers offers very good sample capacity, peak symmetry and retention time reproducibility.

1. M.O. Fogwill and K.B. Thurbide, Anal. Chem., 82(24), 10060–10067 (2010).

A discovery during the investigation of subcritical water chromatography has led to a novel method that could provide a green and cheap addition to the analytical chemist?s toolbox.

Columnless separation with water and CO2

Malted barley is the most common grain used in the beer making process. In recent years, small grains such as barley have been significantly affected by common fungal genera such as fusarium, alternaria, aspergillus and penicillium, all of which have shown high producing potential for a wide range of mycotoxins — toxic secondary metabolites. The production of mycotoxins is not homogenous and can occur with the growth of toxinogenic species during steeping, germination and kilning in the malting process.

Mycotoxins pose a significant threat to human and animal health through ingestion. Toxins that enter the blood stream or lymphatic system can, for instance, prevent protein synthesis, damage macrophage systems, inhibit particle clearance of the lung and increase sensitivity to bacterial endotoxin. As a result, the European Union has published a recommendation on the prevention and reduction of fusarium toxins in cereals and cereal-based products [Comission Regulation (EC) 1881/2006]. The US Food and Drug Administration (FDA) has also regulated and enforced limits on concentrations of mycotoxins in food since 1985.

To comply with these regulations, an accurate and high-resolution method of screening is required. In addition, there is a growing demand within analytical laboratories for more stream-lined sample preparation techniques to reduce timeframes and increase overall throughput. With respect to the determination step, full spectral data acquisition techniques are increasing in popularity because of their ease of use and capacity for retrospective archived data mining. The most common full spectral mass-spectrometric approach for food analysis has typically been time‑of‑flight (TOF-MS) with a typical resolving power of approximately 12 500 FWHM (full width half maximum). However, in complex food matrices such as beer, this limited mass resolving power leads to the risk of inaccurate mass measurements caused by unresolved background matrix interferences.

Systems based on Orbitrap technology allow scientists to routinely achieve mass resolving power of up to 100 000 FWHM and maintain excellent mass accuracy up to 

The Detection and Quantification of Multi-mycotoxins in Beer Samples using Orbitrap Technology with UHPLC.

The Detection and Quantification of Multi-mycotoxins in Beer Samples using Orbitrap Technology with UHPLC

GPC/SEC is used to separate, identify and characterize macromolecules with respect to their molar mass averages and molar mass distribution (MMD). The precision and accuracy of the results depends, amongst other parameters, on the selection of the proper separation columns. 

A proper column selection in GPC/SEC always includes finding a compromise between separation range, analytical quality, analysis time and solvent consumption. A wide separation range is required for highest versatility and applicability, a good resolution is required for the in-depth analysis, especially for a detailed MMD. Analysis time and solvent consumption are important especially for quality control in high temperature GPC and when expensive solvents are used.

The dependence of GPC/SEC column characteristics and experimental parameters on the resolution is quite complex. Column material particle size and packing quality, pore size and pore size distribution, solvent viscosity, temperature and flow-rate, as well as sample concentration and other factors influence the mass transfer and, therefore, the resolution. 

A measure for the resolution can either be the plate count, N, or (recommended for GPC/SEC) the specific resolution, Rsp. For the specific resolution the peak standard deviation (which is proportional to the peak width) and the slope of the calibration curve are required.

The precision and accuracy of the results depends, amongst other parameters, on the selection of the proper separation columns.

The Column-02-04-2011

Studying morning breath

Reanalysing Viking results

Gnats off!

Columnless separation with water and CO2

The Detection and Quantification of Multi-mycotoxins in Beer Samples using Orbitrap Technology with UHPLC

Tips & Tricks: GPC/SEC Increase Resolution and Separation Range

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