Js. Alvarado et Jw. Carnahan, REDUCTIVE PYROLYSIS FOR THE DETERMINATION OF AQUEOUS SULFUR-COMPOUNDSWITH A HELIUM MICROWAVE-INDUCED PLASMA, Analytical chemistry, 65(22), 1993, pp. 3295-3298
A method for the determination of aqueous sulfur is presented. Sulfur-
containing compounds were converted to H2S by a noncatalytic reductive
pyrolysis at 1050-degrees-C in the presence of hydrogen gas. The resu
ltant H2S was trapped by condensation in a liquid nitrogen trap. Follo
wing preconcentration, flash vaporization into a flowing helium stream
routed the H2S to a 1.6-kW helium microwave-induced plasma for atomic
emission detection. Analytical effects of pyrolysis temperature, hydr
ogen flow rate, and sample introduction rate were studied for aqueous
solutions of cysteine, methionine, dimethyl sulfoxide, and ammonium su
lfate. Results showed linear responses and detection limits of 30 part
s per billion when the 921.3-nm nonresonant sulfur atom emission line
was monitored and 400 parts per trillion when the resonant sulfur line
at 180.73 nm was observed.