Improved sensitivity and characterization of high-speed ion chromatography of inorganic anions

In this work, a reversed-phase monolithic column was permanently coated with didodecyldimethylammonium bromide (DDAB) to perform ultrafast separations of iodate, chloride, nitrite, bromide, nitrate, phosphate, and sulfate in as little as 30 s. Separations were performed using 6 mM o-cyanophenol (pH 7.0) at flow rates up to 10 mL/min and suppressed conductivity detection. Detection limits in the parts-per-billion range were observed for all anions studied (e.g., ranging from 30 ppb for phosphate to 4 ppb for sulfate). The reproducibility was 0.7 and 0.4% RSD for retention time and peak area, respectively. Coated columns were stable for up to 12 h of continuous use at 5 mL/min (i.e., 1-min separations).