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 new simple method for determination of ozone in ambient air is presented. The reaction employed is based on the known ozonolysis of indigo dye. The indigotrisulfonate molecule contains one carbon-carbon double bond (C C), which reacts with ozone and generates isatinsulfonates and sulfoanthranilate. The quantitatively formed sulfoanthranilate presents fluorescence (λ ex 245 nm, λ em 400 nm). Ozone was collected using two cellulose filters coated with 40 μL of 1.0 × 10 − 3 mol L − 1 of indigotrisulfonate. The analytical response was linear in the range 0-150 ppbv ozone, and a detection limit of 7 ppbv was achieved using a sampling time of 15 min and an optimum sampling air flow rate of 0.4 L min − 1. There was no interference from sulfur dioxide, formaldehyde or nitrogen dioxide. The ozonolysis mechanism and the reaction products are discussed.
A new electrochemical methodology has been developed for the detection of ozone using multiwalled carbon nanotubes (MWCNT). The method presented here is based on the reaction of ozone with indigo blue dye producing anthranilic acid (ATN). The electrochemical profile of ATN on an electrode of glassy carbon (GC) modified with MWCNT showed an oxidation peak potential at 750 mV vs. Ag/AgCl. An analytical method was developed using differential pulse voltammetry (DPV) to determine ATN in a range of 50-400 nmol L
À1, with a detection limit of 9.7 nmol L À1 . Ozonated water samples were successfully analyzed by GC/MWCNT electrode and the recovery procedure yielded values between of 96.5 and 102.3 %.
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