Rapid and easy quantification of elemental sulphur in aqueous samples from biological reactors: the turbidimetric method revisited

ABSTRACT

Recent developments in wastewater treatment have led to a renewed interest to obtain elemental sulphur (S°) as a by-product from bioreactors. However, practical studies are limited by the gap of adequate analytical techniques for its determination. This paper provides a statistical study and matrix effect evaluation of an adapted spectrophotometric method for routine S° analyses in aqueous samples, based on a methodology previously described by Hart (1961). Four complex matrices were tested: domestic sewage and effluent samples from three different bioreactors. Tested performance criteria included linearity, matrix effect, limit of detection and quantification and S° recovery. Results were linear (R² = 0.99994) in the studied range (5 to 100 mg S° L⁻¹) and no matrix effect was observed. The accuracy was based on recovery values that varied from 100% to 106%. The colloidal S° separation and extraction protocol was also considered suitable for aqueous samples, reaching more than 99.0% of S° recovery.

KEYWORDS:

• Spectrophotometric method
• elemental sulphur extraction
• matrix effect
• analytical method validation
• wastewater samples
• elemental sulphur analysis

Acknowledgments

This study was financially supported by the São Paulo Research Foundation (FAPESP) – grant numbers 2015/18976-0 and 2015/06246-7, the National Council for Scientific and Technological Development (CNPq) – process number 141906/2014-6, and the Coordination for the Improvement of Higher Education Personnel (CAPES).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo [2015/06246-7,2015/18976-0]; Conselho Nacional de Desenvolvimento Científico e Tecnológico [141906/2014-6].