Determination of nanomole amounts of sulphur dioxide in air by flow-injecton conductimetry with on-line preconcentration

✍ Scribed by I. Gács; R. Ferraroli

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 718 KB
• Volume: 269
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(92)85400-z

✦ Synopsis

A simple and sensmve flow-inJectIon techmque for measurmg nanomole amounts of sulphur dloxlde m gaseous atmospheres 1s presented The samples are passed through 0 2 M sulphamlc acid solution to ehmmate constituents interfering with the final electrolytic conductlvlty measurement Sulphur dloxlde 1s preconcentrated from the carrier gas stream by absorption m a capillary denuder tube coated urlth 0 02 M hydrogen peroxide solution The sulphurlc acid formed m the hquld film 1s then eluted with a stream of the absorbent circulated through an electrolytic conductlvlty mlcrodetector The change m specific conductance due to the presence of the sulphunc acid m the effluent stream IS lmearly related to the amount of sulphur dloxlde m the sample (up to 55 nmol) The method can also be applied to the analysis of aqueous sulphlte solutions In this case the samples are injected mto the sulphamlc acid, and the acidic solution 1s then stnpped with a stream of mtrogen The hmlt of detection for aqueous samples IS 1 pg I-' and for air samples 4 pg mT3 A simple determmatlon, mcludmg sample preparation, takes 7 mm The preclston IS better than 5% (P = 95%) for 2 5-50 nmol of sulphur dloxlde The selectlvlty of the system wth respect to nitrogen oxides, ammonia, hydrogen chloride and hydrogen sulphlde was also exammed