摘要：Instead of toxic sodium mercuric tetrachloride solution, triethanolamine (TEA) solution was used as an absorbent for the determination of sulfur dioxide in air. Absorption efficiency of TEA solution for sulfur dioxide was more than 99%, and the resulting sulfite ion was quite stable against aeration and solar irradiation. This procedure is carried out as follows : In an absorption tube, 20 ml of 1% TEA solution containing 0.001% sodium azide is place and the sample gas is passed through this solution at the flow rate of 11/min. To 10 ml of this solution, 2 ml of p-rosaniline formaldehyde reagent (0.04 g of p-rosaniline hydrochloride, 20 ml of hydrochloric acid, and 100 ml of 0.2% formaldehyde solution mixed and diluted with water to 200 ml) is added, allowed to stand for 35 min, and absorbance of the mixture is read at 560 nm. The presence of NO-3, Cl-, S2-, SO2-4, and NH+4 (the molar ratio of each ion/SO2 was 100) does not interfere in this determination but NO-2 showed negative interference, and this interference was completely removed by the addition of sodium azide to the absorption solution. Accuracy, reproducibility, and sensitivity of this method were the same as the usual p-rosaniline method (West's method).
