Publications by authors named "Sivanildo S Borges"

A photometric procedure for the determination of ClO(-) in tap water employing a miniaturized multicommuted flow analysis setup and an LED-based photometer is described. The analytical procedure was implemented using leucocrystal violet (LCV; 4,4',4''-methylidynetris (N,N-dimethylaniline), C(25)H(31)N(3)) as a chromogenic reagent. Solenoid micropumps employed for solutions propelling were assembled together with the photometer in order to compose a compact unit of small dimensions.

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In this work a downscaled multicommuted flow injection analysis setup for photometric determination is described. The setup consists of a flow system module and a LED based photometer, with a total internal volume of about 170 microL. The system was tested by developing an analytical procedure for the photometric determination of iodate in table salt using N,N-diethyl-henylenediamine (DPD) as the chromogenic reagent.

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In this work, an automatic device to deliver titrant solution into a titration chamber with the ability to determine the dispensed volume of solution, with good precision independent of both elapsed time and flow rate, is proposed. A glass tube maintained at the vertical position was employed as a container for the titrant solution. Electronic devices were coupled to the glass tube in order to control its filling with titrant solution, as well as the stepwise solution delivering into the titration chamber.

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An automatic reagentless photometric procedure for the determination of ethanol in red wine is described. The procedure was based on a falling drop system that was implemented by employing a flow injection analysis manifold. The detection system comprised an infrared LED and a phototransistor.

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Near infrared emission caused by ultrasonic excitation is demonstrated for the first time in this work. The instrument is constituted of an acousto-optical tunable filter-based spectrometer, an ultrasonic processor connected to a titanium alloy ultrasonic probe and a cylindrical borosilicate flask containing the sample to be excited. The radiation emitted by the sample is collected by a concave mirror and sent to the spectrometer.

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Few methods, such as coulometrics, have been developed to produce reagents in situ for analytical purposes. In this work the concept related to the generation of ultrasound-assisted reagents was exploited to yield oxidizing species in batch and flow systems of analysis. To evaluate the efficiency of ultrasound-assisted reagent generation, the conversion of Fe(2+) to Fe(3+) associated with the 1,10-o-phenantroline spectrophotometric method was tested to compare the oxidizing power of the produced species from pure water and aqueous solutions saturated with CCl(4) or CHCl(3) irradiated ultrasonic waves.

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