On-line Determination of Sulfide by the ‘Methylene Blue Method’ With Diode-laser-based Fluorescence Detection

Abstract

The application of an inexpensive, compact, solid-state, fluorescence-based detector for flow injection analysis to the determination of sulfide by the 'Methylene Blue Method', viz., production of Methylene Blue (MB) via the oxidative coupling of sulfide with N,N-dimethyl-pphenylenediamine (DMPD) in the presence of iron(III), is described. The use of fluorescence-based detection allows the reaction to be performed on-line under less corrosive, albeit sub-optimum, reaction conditions. The detector uses a 670 nm diode laser as the excitation source and inexpensive photodiodes as detector elements; a color filter (used to block scattered laser light) is the only other optical component of the detector. The fluorescence signal resulting from the MB formed on-line is linear over the range 0.75-15.0 mg l 21 injected sulfide, with a limit of detection of 0.08 mg l 21 injected sulfide when 9.0 M H 2 SO 4 is used in the DMPD carrier stream, and 1-2 mg l 21 when less acidic carrier streams are employed. Use of this method for analysis of sulfide unknowns in aqueous solution and in a simulated waste water matrix demonstrates that unknown sulfide samples can be analysed reproducibly.

Carbamodithioate-Based Dual Functional Fluorescent Probe for Hg2+ and S2−

“…Thus, the detection of sulfide anion is becoming very important from industrial, environmental, and biological points of view. A variety of detection techniques have been developed for the determination of sulfide anion [69][70][71][72][73], in which fluorimetry has received considerable attention due to its high sensitivity and easy detection.…”

Flow Injection Analysis of Sulfide Using a Cinder/Tetracyano Nikelate Modified Screen-Printed Electrode

“…Sodium sulfide (Na 2 S · 9H 2 O) and K 2 Ni(CN) 4 were bought from Aldrich (Milwaukee, WI, USA) and used as received. All the other compounds (ACS-certified reagent grade) were used without further purification.…”

“…The best conditions, as described below, were thus chosen in fabricating the cinder/NiTcSPE in the subsequent studies. In brief, the cinder/SPE coating with 90% : 10% (w/w) carbon ink-cinder dissolved in a dichloromethane-acetonitrile solution was used to prepare the cinder/NiTcSPE by scanning in pH 2 NH 4 Cl/HCl solution containing 10 mM [Ni II (CN) 4 ] 2À in the potential window of À 0.5 to 1.0 V for 30 cycles at a scan rate of 50 mV/s.…”

Spectrophotometric determination of hydrogen sulfide in environmental samples using sodium 1,2-naphthoquinone-4-sulfonate and response surface methodology

“…However, application of these methods is not simple and includes several stages. Hence, relatively simpler methods such as titration (Balasubramanian and Pugalenthi 2000), spectrophotometry (Evans 1967;Ferrer et al 2004;Silva et al 2001Silva et al , 2003Rodriguez-Fernandez et al 1999;Kuban et al 1992;Siegel 1965;Fischer 1883) and spectrofluorimetry (Rodriguez-Fernandez et al 1999;Choi and Hawkins 1997;Axelrod et al 1969;Spaziani et al 1997;Gohda et al 1986;Yang et al 2000) have been introduced for this purpose.…”