Quality changes during storage of cooked and sliced meat products measured with PTR-MS and HS-GC-MS.

The changes in the VOC composition of industrially produced saveloy were measured with Proton-Transfer-Reaction Mass-Spectrometry (PTR-MS) and HeadSpace Gas chromatography-mass spectrometry (HS-GC-MS) during a six weeks storage period. A decrease in the volatile organic compounds contributing to the fresh aroma of saveloy was the main change observed with both PTR-MS and HS-GC-MS. Samples of four other types of cooked and sliced meat product were measured with PTR-MS in the middle and at the end of the four week shelf-life period. These measurements showed an increase in m/z 69, 71, 87 and 89 for the pork loin and in m/z 61 for the herbal saveloy samples. These ions were assigned to the microbial spoilage markers: acetic acid, 2- and 3-methylbutanol, 2- and 3-methylbutanal, diacetyl and acetoin. Overall, this study shows that PTR-MS has potential for quality control of cooked and sliced meat products.

Use of non-thermal plasma and UV-light for removal of odour from sludge treatment.

Non-thermal plasma (NTP) systems can be used for abatement of odour nuisances. Odour reductions are achieved by radical-initiated oxidation and dust collection in the plasma reactor. For some emissions a sequence of NTP followed by UV-light can improve the odour reduction further. This study was conducted to evaluate the efficiency of NTP technology combined with UV-light towards odour emissions from sludge treatment. Air from a pilot sludge dryer was treated with a pilot NTP and a UV unit. The effect of using an acid scrubber upstream the NTP system was also tested. Thermal desorption gas chromatography and mass spectrometry (TD-GC/MS) was used to analyse samples taken from the inlet and the outlet of the NTP system. The TD-GC/MS used was also equipped with a sniffing port that made it possible to record odour-active compounds eluting from the column. Relative amounts of odour-active compounds in the inlet and the outlet flow from the NTP system were compared. Bag samples from inlet and outlet were also separately analysed by an external lab and by two operators using a one-man olfactometer, a modified NasalRanger(TM). These results indicated a significant odour removal efficiency of 70-90% depending on the settings and combinations of abatement equipment.

Photodegradation of nitro-PAHs in viscous organic media used as models of organic aerosols.

Many types of organic aerosol material have been found to behave as viscous liquids. In the current work, photodegradation of selected nitrated polycyclic aromatic compounds, 1-nitropyrene and 3-nitrofluoranthene, in viscous organic phases used as model systems for organic aerosols has been investigated. Experiments have been conducted in the presence and absence of anthraquinone, an atmospherically relevant photochemical radical sensitizer. The photodegradation of nitro-PAH is strongly accelerated by the presence of anthraquinone, and a viscous medium does not inhibit the photoinduced decay of nitro-PAH. In fact, the effect of anthraquinone is more pronounced in a viscous solvent containing tertiary hydrogen, DOP, compared to cyclohexane, a nonviscous solvent. This is related to a faster decay of anthraquinone in DOP and hence, presumably, a higher radical yield in DOP. The nitro-PAH degradation in DOP is faster at higher temperature; an observation primarily ascribed to faster diffusion at higher temperature giving rise to more efficient radical formation. In glycerine, a polar viscous solvent, significant formation of amino-PAH occurs due to photoreduction of the nitro-PAH. This is also the case in N2-purged guaiacol, a model substance for wood smoke organic material. Nitro-PAH photoreduction is enabled by the presence of hydrogen-atom donors and low levels of dissolved O2. A simple approach to estimate the O2 concentration in atmospheric organic aerosol material is presented. Low levels of O2 are predicted for wood smoke and secondary organic aerosol making amino-PAH formation in this aerosol material an interesting possibility.

The variation of street air levels of PAH and other mutagenic PAC in relation to regulations of traffic emissions and the impact of atmospheric processes.

The occurrence of particle associated PAH and other mutagenic PAC was determined in 1996 in the street air of Copenhagen. In addition, particle extracts were tested for mutagenicity. The measurements were compared with previous measurements in 1992/1993. The levels had decreased in this period. The decrease was caused by an implementation of light diesel fuels for buses and the exchange of older petrol-driven passenger cars with catalyst-equipped new ones. About 65% of the reduction was caused by the application of the light diesel fuels. Under special conditions, chemical processes in the atmosphere produced many more mutagens than the direct emissions. The concentrations of S-PAC and N-PAC were 10 times lower than those of PAH, while the levels of oxy-PAH were in the same order of magnitude as those of PAH. Benzanthrone, an oxy-PAH, is proposed to be formed in the atmosphere in addition to direct emissions. Benzo(a)pyrene, often applied as an air quality criteria indicator, was photochemically degraded in the atmosphere. A strong increase in the mutagenic activities was observed to coincide with a depletion of benzo(a)pyrene.