[The method of determination for sulfur dioxide in the air of workplace by ion chromatography without derivatization].

ABSTRACT

Objective: To establish a method for the determination of sulfur dioxide (SO2) in the air of workplace, which including the process of collection by absorption in triethanolamine aqueous solution and the process of analysis and detection by iron chromatography directly without derivatization. Methods: SO2 in the air of workplace was collected at a flow rate of 0.5 L/min for 15 min through 10 ml of 3% triethanolamine aqueous solution filled in a porous glass plate absorption tube. The absorption solution passed through IonPacAS14A analytical column (4 mm×250 mm) and IonPacAG14 protective column (4 mm×50 mm) at a column temperature of 30 ℃, using Na2CO3 (3.0 mmol/L) -NaHCO3 (1.0 mmol/L) as mobile phase with the flow rate of 1.2 ml/min, and was detected by conductivity detector. Results: It showed that SO2 in triethanolamine solution could be stored for at least 7 d at room temperature (25 ℃) and 37 ℃. There was a linear relationship within the determination range of 0-8.00 µg/ml, the linear correlation coefficient was 0.9999. The sampling absorption efficiency was 98.1%-100.0%, the detection limit of the method was 0.018 µg/ml, the minimum detection concentration was 0.024 mg/m3 (based on V0=7.5 L) . The recovery rate was 99.22%-101.69%, the intra batch precision was 0.41%-1.34%, and the inter batch precision was 0.73%-1.77%. Conclusion: The method has the advantages of simple operation, high sensitivity and good accuracy. It can prevent SO2 from being oxidized and realize the direct detection of SO2 in the air of workplace without derivation.