Extraction of elemental sulfur from an aqueous suspension for analysis by high-performance liquid chromatography

A bioreactor is being developed that produces elemental sulfur suspended in aqueous bioreactor contents. The concentration of elemental sulfur must be measured explicitly in order to study the efficiency of the conversion of sulfide to elemental sulfur. Extracting the sample with ethanol gave erroneous results when sulfide was present in solution. The extraction of aqueous elemental sulfur into petroleum ether prior to colorimetric determination was tested. When the aqueous matrix was simply deionized water, the extraction was poor. The development of a method of extraction of the sulfur into chloroform prior to quantification by high-performance liquid chromatography is described. The efficiency of the extraction was found to be greater than 90% in all matrixes tested and linear for aqueous elemental sulfur concentrations up to 200 mg/L.