Abstract: Analytical methods and devices according to the present disclosure may be used to assay the concentration of malic acid, or related species, in a sample, e.g., preparations of fruit, vegetables, juice, and/or wine. Liquid samples are combined with a reaction mixture, incubated, and a parameter characteristic of the resulting incubated mixture is measured. During the incubation, the reaction mixture generally reacts with the liquid sample to transform malic acid or related species that is present in the liquid sample. The measured parameter may be pressure, pH, an amount (e.g., volume, mass) of CO2 generated during the incubation, a parameter related to the foregoing, and/or any other parameter related to the amount of malic acid or related species transformed.

Abstract: A device and reagents to be used in conjunction therewith for the determination of the level of sulfite or related species, including sulfur dioxide (SO2), in red or white wine, musts, beer, juices, water, industrial process streams and other opaque media is described. The device provides electrodes and circuits designed for amperometric detection of the titration endpoint and for indicating by sight, sound or touch when the endpoint has been reached. The reagents allow quantitative volumetric determination of the iodometric endpoint when used with the device. The sulfite or related species levels are related directly to the volume of the quantitative reagents used.