Tag archive for instrumentation

Don’t Judge a Book by Its Cover … Judge by Its Smell

OldBooksA recently published article in the journal Analytical Chemistry discusses the distinct “aroma” produced by old books and aims to better describe – at the molecular level – that musty smell you encounter in the back rooms of libraries.  Volatile organic compounds (VOCs) are responsible for the odor … hundreds of them.  The exact combination of VOCs results from degradation pathways that are dependent on the original material composition – including the paper source, applied media (e.g. inks) and binding.  The exact composition of the off-gassing VOCs can hold valuable information regarding the condition of the materials and possible ways to aid in preservation.  Unfortunately, most testing methods used to date involve destructive sampling techniques.  The authors of this paper have devised a new approach that involves non-destructive head-space sampling of the emitted VOCs, combined with some advanced statistical analyses (a method termed “material degradomics” … a twist on more popular terms like proteomics or metabolomics).  Although hundreds of potential VOCs can be emitted, the authors focused in on 15 that can be used as markers to track the degradation of paper and help optimize its preservation.  Some of these markers include compounds such as benzaldehyde, nonanal, furfural, acetic acid, hexadecane, and 2-ethylhexanol (among others).

Now we can have a whole new appreciation for those leather-bound books and libraries that smell of rich mahogany (and VOCs)…

Anal. Chem., 2009, 81 (20), pp 8617–8622, DOI: 10.1021/ac9016049.

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Chemical Profile of Decomposition Acquired to Improve Technology for Disasters and Crime

Jones Press Conference-1wFor many years, search dogs have been the standard for the discovery and retrieval of human cadavers in disasters and crimes. The problems with this method are the cost and time it takes to train these search dogs. A device to detect the gases given off of a cadaver would be cheaper and less time consuming than training detection dogs. When a cadaver decomposes, a series of gases are given off over time. In order to develop a device that could detect these gases, experiments had to be performed to discover which gases are given off in different stages of decomposition and also to analyze how the environment affects decomposition in different situations.

Such a device could have been helpful in the search for survivors and cadavers of the earthquake in Indonesia in September. Rescue workers were still searching with detection dogs on the fourth day, and hopes for finding survivors are slim. With a device to detect gases released during decomposition, the search process may have been accelerated.

The first tests were performed on human cadavers, but the human cadavers were not delivered until about two or three days after the person had died. There are certain gases, such as cadaverine and putrescine, that are given off very early in the decomposition process and would therefore be undetected by the time the scientists received the cadavers. Dan Sykes, Ph.D., and student, Sarah A. Jones, from Pennsylvania State University, studied the decomposition of pigs because they display the same stages of decomposition as humans. Sykes and Jones euthanized three pigs and put them into containers that were open at the bottom to allow for insects and air to reach the bodies of the pigs. The gases given off during the decomposition process were collected and analyzed by a solid phase micro extraction (SPME) bundle with polyacrylate fibers. These polyacrylate fibers are polar and are commonly used to collect air samples. Similarly, the gases given off by the body were collected into the fibers. The samples were collected every six to twelve hours over the period of one week and then analyzed using GC-MS. Certain gases, such as indole and putrescine, were not given off until later in the decomposition process, but precursor molecules to these gases were detected, which helped to estimate when the gases would be given off. Using this method, Sykes and Jones were able to create a timeline of decomposition for the pigs, which closely resembles the timeline for the decomposition of a human cadaver. Now that the decomposition timeline has been created, it is possible to begin to set up different scenarios in order to apply the timeline to real life situations of decomposition in disasters and crime scenes.

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