Post-mortem volatiles of vertebrate tissue

Volatile emission during vertebrate decay is a complex process that is understood incompletely. It depends on many factors. The main factor is the metabolism of the microbial species present inside and on the vertebrate. In this review, we combine the results from studies on volatile organic compounds (VOCs) detected during this decay process and those on the biochemical formation of VOCs in order to improve our understanding of the decay process. Micro-organisms are the main producers of VOCs, which are by- or end-products of microbial metabolism. Many microbes are already present inside and on a vertebrate, and these can initiate microbial decay. In addition, micro-organisms from the environment colonize the cadaver. The composition of microbial communities is complex, and communities of different species interact with each other in succession. In comparison to the complexity of the decay process, the resulting volatile pattern does show some consistency. Therefore, the possibility of an existence of a time-dependent core volatile pattern, which could be used for applications in areas such as forensics or food science, is discussed. Possible microbial interactions that might alter the process of decay are highlighted

European interlaboratory comparison of breath (CO2)-C-13 analysis

The BIOMED I programme Stable Isotopes in Gastroenterology and Nutrition (SIGN) has focused upon evaluation and standardisation of stable isotope breath tests using C-13 labelled substrates. The programme dealt with comparison of C-13 substrates, test meats, test conditions, analysis techniques, and calculation procedures. Analytical techniques applied for (CO2)-C-13 analysis were evaluated by taking an inventory of instrumentation, calibration protocols, and analysis procedures. Two ring tests were initiated measuring C-13 abundances of carbonate materials. Evaluating the data it was found that seven different models of isotope ratio mass spectrometers (IRMS) were used by the participants applying both the dual inlet system and the continuous flow configuration. Eight different brands of certified C-13 reference materials were used with a C-13 abundance varying from delta(13)C(PDB) -37.2 to +2.0 parts per thousand. CO2 was liberated from certified material by three techniques and different working standards were used varying from -47.4 to +0.4 parts per thousand in their delta(13)C(PDB) value. The standard deviations (SDs) found for all measurements by all participants were 0.25 parts per thousand and 0.50 parts per thousand for two carbonates used in the ring tests. The individual variation for the single participants varied from 0.02 parts per thousand (dual inlet system) to 0.14 parts per thousand (continuous flow system). The measurement of the difference between two carbonates showed a SD of 0.33 parts per thousand calculated for all participants. Internal precision of IRMS as indicated by the specifications of the different instrument suppliers i