On-line analysis of NH3, CO2, and SO2 diffusion through microporous Teflon

Dynamic responses of self-made potentiometric NH3, CO2, and SO2 sensitive gas sensors are followed in the 10-5-5×10-3 M concentration range. By least squares fitting of potential versus time curves, Dk product values at the diffusion of NH3, CO2, and SO2 through microporous Teflon are calculated. The obtained results are fairly reflected by the behavior of the sensor. Measurements of potential versus time in mixed solutions of CO2 and SO2 with the CO2 sensitive sensor indicate the presence of the interferent.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Influence of Intermittent Heating during Maceration on the Antioxidant Capacity of Some Grape Seeds and Skins

Ethanolic extracts from seeds and skins of three red grape varieties, namely, 'Cabernet Sauvignon', 'Merlot' and 'Burgund' from a Romanian winery, were prepared by maceration using different temperature conditions. The stable free radicals DPPH (2, 2-diphenyl- 1-picrylhydrazyl) and Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidin-N-oxyl) were used in order to evaluate the antioxidant capacity of the extracts. The variation in time of free radical concentration was followed by double integration of the EPR spectra of the samples obtained after maceration under different conditions (room temperature and intermittent heating). Results showed that the antioxidant capacity depends on the nature of analysed samples (either being seeds or skins) and grape variety. The results also show that the intermittent heating during maceration leads to a decrease of the antioxidant capacity of samples

A sensor probe for the continuous in situ monitoring of ammonia leakage in secondary refrigerant systems

Ammonia is becoming more widely used in refrigeration systems due to the phasing out of CFCs and HCFCs. However, ammonia is a toxic gas and its leakage from refrigeration systems can lead to human exposure and contamination of refrigerated food stuffs. There is a lack of devices capable of the direct and continuous monitoring of leakage of ammonia into secondary refrigerant systems. Here we demonstrate an ammonia measurement probe for continuous contact monitoring of secondary refrigerants. The probe was based on an ammonia-sensitive film of inkjet printed polyaniline nanoparticles deposited onto an interdigitated electrode array and enclosed behind a polytetrafluoroethylene membrane. When operated impedimetrically, the probe was capable of the detection of ammonia across the industrially relevant range of 0 to 100 ppm from +4 to -15°C in water and brine. Operation of the probe as a simple threshold alarm without the requirement for temperature monitoring or calibration is illustrated. © 2013 The Royal Society of Chemistry