Sulfur dioxide analytical techniques

The Karl Fischer titration is the analytical method most specific for water and is also the most convenient to use. The basis of the Karl Fischer titration is the reaction of water with iodine and sulfur dioxide (Equation I). In the early development of this analytical technique, the solution containing water was titrated... 

Other methods of quantitative analysis, which are much more accurate and applicable to wider ranges of mixtures, include GC, mass spectrometry (MS), the GC-MS combination, in which products separated by GC are detected by MS, infrared spectroscopy, specific sensors to measure water, sulfur dioxide, etc., and all other appropriate techniques, which may include wet chemical analytical methods. 

The most used analytical technique for SO2 monitoring is based on fluorescence. Excitation of sulfur dioxide molecules by ultraviolet radiation (UV) in the 190-230 nm region gives an emitting fluorescent radiation, whose wavelength and intensity are directly proportional to the concentration of sulfur dioxide. The main interfering compound is represented by polycyclic aromatic hydrocarbons to eliminate their effect, the analyzers are equipped with a permeation device which selectively removes hydrocarbon molecules from the gas sample. ... 

Although analytical SFC was demonstrated in the early 1960s, it has only been in recent years that the availability of adequate high resolution packed and capillary SFC columns and instrumentation has led to renewed interest in the technique. Plasma emission is a natural development because of its use in GC and HPLC. A surfatron MIP sustained in helium has been employed for SFC detection, giving sulfur-specific detection at 921.3 nm with a 25 pg s limit for thiophene [28]. An argon high efficiency MIP has been interfaced with packed column SFC and the separation and detection of ferrocene and derivatives achieved with iron specific detection. Methanol modifier concentrations to 5% were tolerated in the carbon dioxide mobile phase [29]. 

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