New analytical methodology for analysing S(IV) species at low pH solutions by one stage titration method (bichromatometry) with a clear colour change. Could potentially replace the state-of-art-method iodometry at low pH analysis due higher accuracy

Annukka Santasalo-Aarnio; Istvan Galfi; Jorma Virtanen; Michael M Gasik

doi:10.1371/journal.pone.0188227

New analytical methodology for analysing S(IV) species at low pH solutions by one stage titration method (bichromatometry) with a clear colour change. Could potentially replace the state-of-art-method iodometry at low pH analysis due higher accuracy

PLoS One. 2017 Nov 16;12(11):e0188227. doi: 10.1371/journal.pone.0188227. eCollection 2017.

Authors

Annukka Santasalo-Aarnio¹, Istvan Galfi¹, Jorma Virtanen¹, Michael M Gasik¹

Affiliation

¹ Department of Chemical and Metallurgical Engineering, School of Chemical Engineering, Aalto University, Aalto, Finland.

Abstract

A new, faster and more reliable analytical methodology for S(IV) species analysis at low pH solutions by bichromatometry is proposed. For decades the state of the art methodology has been iodometry that is still well justified method for neutral solutions, thus at low pH media possess various side reactions increasing inaccuracy. In contrast, the new methodology has no side reactions at low pH media, requires only one titration step and provides a clear color change if S(IV) species are present in the solution. The method is validated using model solutions with known concentrations and applied to analyses of gaseous SO2 from purged solution in low pH media samples. The results indicate that bichromatometry can accurately analyze SO2 from liquid samples having pH even below 0 relevant to metallurgical industrial processes.

MeSH terms

Color*
Hydrogen-Ion Concentration
Reproducibility of Results
Solutions
Sulfur / chemistry*

Substances

Solutions
Sulfur

Grants and funding

The European Union's Seventh Framework Programme (FP7), the Fuel Cell and Hydrogen Joint Undertaking, under grant agreement n° 325320 of the SOL2HY2 project. The funding was received by prof. M.M. Gasik. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.