Determination of Nine Kinds of Trace Anions in Electronic-Grade Isopropanol Based on 2D Valve-Switching Ion Chromatography

In this study, two-dimensional ion chromatographic method was developed for the determination of fluoride ions (F−), chloride ions (Cl−), nitrite ions (NO2−), bromide ions (Br−), nitrate ions (NO3−), chloride ions (ClO3−), sulfate ions (SO42−), oxalate ions (C2O42−), and phosphate ions (PO43−) in electronic-grade isopropanol based on the valve-switching technique in ultraclean environment. Through the optimization of pretreatment conditions as well as ion chromatographic conditions, an external pump with ultrapure water was used to assist the large-volume injection and enrichment column enrichment in the first dimension system. Finally, the target anions in the second dimension valve-switching enrichment column were eluted by potassium hydroxide to the ion exchange column system for analysis. The eluent was potassium hydroxide, the column temperature was 30 °C, the flow rate was 1.0 mL/min, and the gradient elution method was used. The analysis time was 35 min, and the internal standard method was used for quantification. The results showed that all the anions showed good linear relationship in the range of 0.5–25 μg/kg, and the linear regression coefficients of the anions were more than 0.999. The recoveries of the anions spiked ranged from 73.2 to 102.9%, and the precision was within 5%, which made the present study a strong reference for the determination of trace anions in other similar water-soluble organic compounds.