Detection of traces of oxidized and reduced sulfur compounds in small samples by combination of different high-performance liquid chromatography methods

Depending on the sulfur species, picomoles of different inorganic sulfur compounds can be detected and separated by HPLC in one arrangement in a sample volume less than 50 mu l. The combination of fluorescence labelling of reduced inorganic sulfur compounds such as sulfide (S2-), sulfite (SO32-) with monobromobimane followed by an extraction of elemental sulfur (S-0) by chloroform treatment enables the detection of all mentioned sulfur compounds as well as sulfate (remaining aqueous phase) in the same sample. While the derivatized compounds could be detected by their fluorescence emission at 480 nm, elemental sulfur is identified by its UV absorption at 263 nm. Sulfate in the remaining aqueous phase is detected by HPLC with indirect UV detection at 254 nm. Detection ranges for the different sulfur compounds examined are as follows: sulfide (5 mu M to 1.5 mM), sulfite (5 mu M to 1.0 mM), thiosulfate (1 mu M to 1.5 mM), elemental sulfur (2 mu M to 32 mM) and sulfate (5 mu M to >1 mM).