I'm looking into sulfur (elementary, H2S production through wild yeast strains, sulfite, etc.) in grape must. Would anyone know material about the possible quantities that can be found, and by which ways sulfur is detected in labs?
Definitely take a look at the articles by Alexey Kamyshny, for using HPLC methods to characterize sulfur species. Sulfides can be easily measured using the methylene blue method (there are many colorimetric kits for doing this), though there are also good sensors out there for sulfide measurement as well. There are test kits for sulfite on the market, some of which are specifically intended for wine making. Measuring elemental sulfur can be a little more tricky. Voltammetry can be used to detect various sulfur species, including elemental sulfur. I've used x-ray absorption spectroscopy and Raman spectroscopy to detect elemental sulfur in my samples, though I wasn't intending quantification through those methods.