Development of a simple method for determination of NO2 in air using digital scanner images.

Nitrogen dioxide (NO2) is an important indicator of atmospheric pollution that is mainly derived from combustion processes. The gas is often present at undesirable levels in both open and closed environments worldwide, requiring monitoring under a variety of different conditions. This work describes the development of a sensitive, selective, and inexpensive method for the determination of NO2 in gaseous samples. The method is based on the processing of digital images of the product of the Griess-Saltzman (GS) colorimetric reaction. NO2 was collected and pre-concentrated using C-18 cartridges impregnated with triethanolamine, followed by elution with 5% methanol solution. The reaction for formation of the colored product only required 300 µL volumes of sample containing reagent, minimizing the generation of chemical wastes. Calibrations using standard atmospheres showed that it was possible to measure NO2 in a concentration range from 5.1 to 100.0 ppb (9.4-188.0 µg m(-3)), using a sampling flow rate of 0.50 L min(-1) and a collection time of 60 min. The limit of detection achieved with a solution volume of 300 µL was 5.0 ppb (9.6 µg m(-3)), with a relative error of 2% and a coefficient of variation of 1.6%.

Ozonized oils: a qualitative and quantitative analysis.

Most of the problems of endodontic origin have a bacterial etiological agent. Thus, there is a continued interest in seeking more effective chemical substances that can replace the camphorated paramonochiorophenol or antibiotics as intracanal medicaments. Among the possible substances, ozone has some interesting biological characteristics: bactericidal action, debriding effect, angiogenesis stimulation capacity and high oxidizing power. The purpose of this study was to chemically evaluate the presence of ozone in sunflower, castor, olive and almond oil, as well as in propylene glycol and byproducts of ozonation, such as formaldehyde. These compounds were ozonized, inserted into empty and sterile vials, and analyzed by testing the reaction between ozone and indigo, for determining the presence of ozone, and subjected to the chromotropic acid test for determining the presence of formaldehyde. It was observed complete absence of ozone in all samples tested and presence of formaldehyde. The bactericidal and healing action of ozonized oils could be attributed to products formed by the ozonation of mineral oils, such as formaldehyde, not to the ozone itself.

Ozonized oils: a qualitative and quantitative analysis

Most of the problems of endodontic origin have a bacterial etiological agent. Thus, there is a continued interest in seeking more effective chemical substances that can replace the camphorated paramonochiorophenol or antibiotics as intracanal medicaments. Among the possible substances, ozone has some interesting biological characteristics: bactericidal action, debriding effect, angiogenesis stimulation capacity and high oxidizing power. The purpose of this study was to chemically evaluate the presence of ozone in sunflower, castor, olive and almond oil, as well as in propylene glycol and byproducts of ozonation, such as formaldehyde. These compounds were ozonized, inserted into empty and sterile vials, and analyzed by testing the reaction between ozone and indigo, for determining the presence of ozone, and subjected to the chromotropic acid test for determining the presence of formaldehyde. It was observed complete absence of ozone in all samples tested and presence of formaldehyde. The bactericidal and healing action of ozonized oils could be attributed to products formed by the ozonation of mineral oils, such as formaldehyde, not to the ozone itself.

A maioria dos problemas de origem endodôntica tem um agente etiológico bacteriano. Assim, existe um interesse permanente em se buscar substâncias químicas mais efetivas e que possam substituir o PMCC ou os antibióticos como curativos de demora. Dentre as possíveis substâncias, o ozônio apresenta algumas características biológicas interessantes: ação bactericida, efeito debridante, estímulo a angiogênese, além do efeito oxidante. O propósito do presente estudo foi avaliar quimicamente a presença de ozônio nos óleos de girassol, rícino, oliva e amêndoas, além do propilenoglicol, bem como subproputos da ozonização, como formaldeído. Essas substâncias foram ozonizadas, inseridas em tubetes anestésicos vazios e esterilizados, e analisadas por meio do teste da reação entre ozônio e índigo, para determinação da presença de ozônio; e teste do ácido cromotrópico, para determinação da presença de formaldeído. Foi observado ausência total de ozônio em todas as amostras testadas, além da presença de formaldeído. A ação bactericida e curativa dos óleos ozonizados poderia ser atribuída aos produtos formados pela ozonização de óleos minerais, como o formaldeído, e não ao ozônio propriamente dito.