Colorimetric determination of ambient ozone using indigo blue droplet

Abstract

Um método simples e sensível, baseado em uma gota líquida, é descrito para medida do ozônio atmosférico. Uma gota de 30 μL de solução de índigo azul é suspensa em uma corrente de ar para amostragem. O ozônio coletado reage com a solução de índigo azul, provocando seu descoramento. O sensor colorimétrico é composto por duas fibras ópticas; a fonte de luz monocromática usada foi um LED vermelho (625 nm). A curva analítica foi construída com concentrações padrão de ozônio, na faixa de 37 a 123 ppbv. O limite de detecção alcançado foi 7,3 ppbv. O método considerado mostrou-se de fácil aplicação e resposta rápida, com um tempo total de análise de apenas 5 minutos. A simple and sensitive method based on a liquid droplet is described for the measurement of atmospheric ozone. A 30 μL drop of indigo blue solution is suspended in a flowing-air sampling stream. The ozone collected reacts with the indigo solution resulting in its decolorization. The colorimetric sensor is composed of two optical fibers and the source of monochromatic light was a red LED (625 nm). The calibration curve was constructed with ozone standard concentrations ranging from 37-123 ppbv. The detection limit achieved was 7.3 ppbv. The method considered here showed itself to be easy to apply with a fast response and a total analysis time of only 5 minutes.

A new fluorescence method for determination of ozone in ambient air

“…The detection limit achieved for ozone determination using the fluorescence technique was similar to those reported for measurements involving bleaching [16]; however, the proposed method is faster and less prone to interferences, resulting in good agreement with ozone concentrations measured using standard commercial analyzers. Fig.…”

“…The product of ozonolysis of the indigo molecule has been described as being two molecules of isatin [15,16,21,22,[24][25][26]. However, the information available concerning the fluorescent properties of isatin is contradictory.…”

“…Chemical reactions that produce color changes form the basis of colorimetric methods in various experimental arrangements, and can be adapted for automated instrumental measurement of ambient ozone [14][15][16][17][18][19][20]. Although some of these techniques are selective and quantitative, the requirement for expensive and complex instrumentation makes most of them unsuitable for routine applications.…”

“…Indigo and its derivatives have been described as reagents for the measurement of ozone in air [14][15][16][17][18][19]. We have previously reported a method based on the reaction of ozone with indigotrisulfonate in impregnated filters [21,22].…”

Headspace microextraction of tin into an aqueous microdrop containing pd(II) and tributyl phosphate for its determination by ETAAS

“…The use of this technique with ETAAS, however, is not straightforward and requires special settings and devices and/or modification of the graphite tube. 7,8 Solid phase microextraction (SPME) 9 and solvent microextraction (SME) 10,11 have been widely used in recent years as powerful tools for the preconcentration and matrix separation of a variety of organic and inorganic compounds. SPME [12][13][14][15][16][17] and headsapace (HS)-SME 18 of tin have been often used in combination with a chromatographic separation step for tin speciation.…”