A methodology for the determination of reductive sulphur in optical and technical glass.
This paper describes an analytical method for the determination of reductive sulphur (S(IV), S(-II)) in glass. The glass sample is dissolved in hydrofluoric/hydrochloric acid mixture and the sulphur is separated via distillation in an apparatus made of polyfluoralkoxyethylene (PFA). The distilled hydrogen sulphide is trapped in buffered boric acid-zinc acetate solution and subsequently determined after conversion to an ethylene blue dye. The range of the method lies within a range of 2-1200mugg(-1) reductive sulphur. The quantification limit for reductive sulphur is 2mugg(-1). Different analysed glass types show either no detectable reductive sulphur or up to 30% of the total sulphur content reductive sulphur. The inter-laboratory standard deviation shown by a round robin test performed is excellent (+/-4mugg(-1); average 59mugg(-1)). Sources of error of the methodology are discussed.
Rohr
Udo
U
SCHOTT GLAS, Chemical Analysis, Hattenbergerstrasse 10, Mainz 55014, Germany.
Meckea
Lothar
L
Strubel
Christine
C