The determination of anions is one of the most important IC applications. Here we have updated Application Note 154 with the 4µm-resin-particle IonPac AS18-Fast-4µm column with expected backpressures approaching the previous system's limitations. In this Application Update, fast anion runs (9 min) were achieved with a gradient separation, saving 4 min run time with while retaining similar chromatography with higher sensitivity than the previous application. This analysis was facilitated by the high pressure capable Dionex Integrion HPIC system configured for Reagent-Free IC.

Ion chromatography is a well-established technique for determining inorganic anions in acid rain. This Technical Note describes the determination of inorganic anions in rain samples by employing high-pressure ion chromatography (HPIC) and the use of a 4 µm particle size column, the Dionex IonPac AS18-4µm.

The method presented here overcomes analyte interference by separating the two chromium using a detection method specific for Cr(VI) that is capable of handling the high-ionic-strength sample matrices generated in many leaching, and digestion procedures. Cr(VI) is separated as the divalent anion on the IonPac AS7 column using ammonium sulfate, ammonium hydroxide eluent. After the separation, Cr(VI) reacts with the color reagent diphenylcarbohydrazide (DPC) and detected by UV absorbance at 520 nm. This method is consistent with U.S. EPA Method 218.6. Please refer to AU179 for an updated method.

In this application, we demonstrate the performance of the Dionex IonPac AS19 column for EPA Method 326.0. This method allows quantification of bromate to 1 μg/L by suppressed conductivity detection with a hydroxide eluent and 0.5 μg/L using postcolumn reaction with UV detection.

This Technical Note describes the determination of inorganic anions in rainwater samples using a Dionex ICS-5000+ capillary HPIC (High-Pressure Ion Chromatography) system, which can be operated continuously at up to 5000 psi. This high-pressure capability, combined with a 4 μm particle ion-exchange column, such as the Dionex IonPac AS18-4µm anion-exchange column, achieves both high sample throughput and excellent resolution simply by increasing the flow rate. Scaling down from standard bore to capillary scale brings many benefits to IC users. An ICS-6000 can be used for this application.