A multi-purpose flow manifold for the spectrophotometric determination of sulphide, sulphite and ethanol involving gas diffusion: Application to wine and molasses analysis

Abstract

A simple and rugged flow set up was designed for spectrophotometric determination of sulphide, sulphite and ethanol aiming at quality assessment of wines, control of industrial fermentation, and selection of yeast strain. The different assays involved gas diffusion through a Teflon planar membrane and were carried out after minor modifications in the manifold, namely reagent composition and total flow rate. Main figures of merit: linear analytical curves=0.50-6.0 mg L(-1)S(2-), 2.5-20.0 mg L(-1) SO3(-) and 5.0-25.0% (v/v) of ethanol; detection limits (3σ)=0.035 mg L(-1)S(2-), 0.2 mg L(-1) SO3(-) and 0.18% (v/v) of ethanol; peak height r.s.d.=2.18% for 4.03 mg L(-1)S(2-) spiked molasses, 2.21% for a 9.82 mg L(-1) SO3(-) wine and 2.07% for a typical wine (12.53% v/v of ethanol), sampling rate=15, 57 and 29 h(-1), reagent consumptions=1.9 µmol of N,N-dimethyl-p-phenylenediamine, 1.68 µg of Malachite green and 0.68 mmol Cr(VI) per determination, respectively.

An integrated platform for gas-diffusion separation and electrochemical determination of ethanol on fermentation broths

“…It is important to highlight that the method herein reported can be used for determination of ethanol in other samples as alcoholic beverages [33][34][35]. Furthermore, the working electrode can be easily changed in order to monitor other volatile compounds like sulfite as sulfur dioxide [51], total ammonia and carbon dioxide [52].…”

“…The employment of separation methods is a potential output to provide selectivity to electroanalytical determination of ethanol in complex samples such as sugar-cane fermentation broth [33]. The method reported herein relies on diffusion of ethanol gas through PTFE membrane from donor solution, standard or sample, to the receptor solution in internal reservoir.…”

“…As only few compounds are sufficiently volatile at specific temperatures, the gas diffusion increases the selectivity of the analytical platform [32]. Furthermore, the membranes can be coupled in systems by flow injection analysis (FIA) to enable continuous monitoring [3,33]. Such separation was already applied to determine ethanol in alcoholic beverages [3,[33][34][35] and fermentation broths [33].…”

“…Furthermore, the membranes can be coupled in systems by flow injection analysis (FIA) to enable continuous monitoring [3,33]. Such separation was already applied to determine ethanol in alcoholic beverages [3,[33][34][35] and fermentation broths [33]. The detection tools used to test the receptor solution are usually spectrophotometric [3,33] or electroanalytical approaches [34,35].…”

Spectrophotometric Determination of Sulphite in Various Water Samples Via Chromium-1,5-Diphenylcarbazide Complex

“…A flow-injection is used for the determination of sulphite in white wines involving gas diffusion through a concentric tubular membrane (11). Other spectrophotometricmethod has been used for determination of sulphide, sulphite and ethanol involving gas diffusion (12), or quantification of sulphite ions in environmental samples (13).…”