1,720,973 research outputs found
High-performance liquid chromatography procedure for the analysis of urinary 3-methoxy-4-hidroxymandelic acid
No full textThe procedure described here shows the advantages of short time, minimal sample, high sensitivity, good accuracy and reproducibility for analyzing VMA concentration in urine. The method is applied to the assay of urine from patients with neuroblastoma, pheochromocytoma and Parkinson's disease. Human urinary VMA values obtained by this method are in agreement with those of other worker
Determinazione simultanea delle fasi particolato e gassosa di IPA aerodispersi mediante campionamento con membrane filtranti funzionalizzate
No full textAttualmente il campionamento dei microinquinanti organici semivolatili come le PCDD/F i PCB e i PAH viene effettuato attraverso la captazione del particolato su membrane filtranti e in alcuni casi impiegando cartucce di materiale adsorbente o assorbente.
I sistemi di campionamento a membrana filtrante sono molto più semplici dei metodi che coinvolgono anche l'impiego di cartucce idonee alla captazione della frazione volatile degli analiti.
Infatti i sistemi per la determinazione del particolato vengono spesso
automatizzati e permettono il campionamento su più filtri.
Campionatori che permettono il campionamento del particolato e della
frazione semivolatile spesso vengono impiegati per singole misure mentre sistemi automatizzati che consentono di cambiare simultaneamente i filtri e le cartucce sono assai rari da incontrare per la elevata complessità e l’elevato costo.
Poiché la frazione semivolatile degli analiti che viene persa con l’utilizzo delle sole membrane filtranti non è prevedibile, un corretto campionamento prevede l’utilizzo dei due sistemi in serie o in parallelo; in questo modo comunque si aumentano sia i costi che la complessità delle analisi, con conseguente possibilità di errori.
Si stanno pertanto sperimentando membrane funzionalizzate al
fine di campionare in un unico stadio sia gli inquinanti in fase particellare che in fase vapore; i primi risultati ottenuti sono molto incoraggianti, sia in termini di
semplificazione del campionamento che riguardo alle modalità delle successive fasi di trattamento ed analisi dei campioni raccolti
HPLC determination of benzydamine and metabolite N-oxide in plasma following oral administration or topical application in man, using fluorimetric detection
No full textEvaluation of the concentration of the toxic 2,3,6,7-tetrachlorobiphenylene in air after an electrical material fire
No full textIt is known that when fires or explosions involve electrical systems, along with PCDDs and PCDFs, polychlorinated biphenylenes (PCBPs) are also produced. These chlorinated tricyclic aromatic pollutants were noticed in fire rubbles and after the World Trade Center destruction. However, the analytical difficulties in developing an efficient method have limited the knowledge of their environmental distribution. In light of the equipotency of 2,3,6,7-TeCBP and 2,3,7,8-TeCDD, PCBPs call for more accurate investigations. In this paper, for the first time, the level and persistence of 2,3,6,7-TeCBP have been investigated in air samples (both indoor and outdoor) after a fire broke out in an industrial building. GC–MS/MS analysis revealed that 2,3,6,7-TeCBP concentrations after the fire (3046 fg/m3 at the “epicentre”) were remarkably higher than that of the 2,3,7,8-TeCDD. Moreover, the monitoring for over two years has demonstrated the persistent nature of this compound. 2,3,6,7-TeCBP was also analyzed in two different ambient air scenario: industrial and periurban areas and in both cases its concentrations were no matter of concern, confirming the correlation of 2,3,6,7-TeCBP with fire episodes. Collectively, 2,3,6,7-TeCBP, because of its toxicity, concentration and persistence, is a crucial compound in the evaluation of the health effects correlated with fires of electrical systems
Environmental impact of co-combustion of polyethylene wastes in a rice husks fueled plant: evaluation of organic micropollutants and PM emissions
No full textCo-combustion of biomass and plastic waste has emerged as one of the most promising approach at the plastic waste management challenge. This strategy is particularly attractive since it can simultaneously solve the increasing energy demand and reduce the plastic wastes volume. However, since the combustion of both plastic wastes and natural materials is a potential source of organic micropollutants, such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs) and of polycyclic aromatic hydrocarbons (PAHs), beside particulate matter, the environmental sustainability of the waste to energy (WtE) co-combustion strategy has to be assessed. To this end, the emissions of dioxin like (dl)-PCBs, PCDD/Fs and PAHs from a 4-MW thermal power plant fueled with rice husk, partially replaced by end-of-life polyethylene (PE) industrial waste (up to 15% of the thermal power of the plant), were investigated. GC-MS/MS analyses have demonstrated that the co-combustion of PE waste and rice husk presents a profile of environmental sustainability. The concentrations of dl-PCBs, PCDD/Fs and PAHs were extremely low and they have remained almost unaffected by introducing PE in feed. In particular, emissions of PCCD/Fs and dl-PCBs in flue gas were in the range 0.6-1.0 and 0.2-0.6 pg TEQ/Nm3, respectively, while PAHs concentrations ranged from 410 to 825 ng/Nm3. Furthermore, the emission factors of these organic pollutants were found to be lower with PE increasing rate while particulate matter emissions were not affected by co-combustions. Collectively, the investigation has demonstrated that the noils of the industrial PE, due to the low content in halides and metals, can be used as auxiliary fuel and energetically recycled through co-combustion with rice husk. This case of study represents an effective application of the WtE strategy and a concrete approach to mitigate the threat of plastic pollution
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