Introduction

ICSpak is a suppressor technology for anion exchange chromatography developed by JASCO. The packing material has a sulfonic acid group chemically bonded to a styrene-divinylbenzene porous polymer and packed in a PEEK column. The suppressor is used in anion chromatography to decrease the background signal from the eluent and to change the sample to an ion-pair with high equivalent conductivity. This suppressor can be re-cycled using regeneration and washing steps. The more sensitive detection of nitrate and nitrite ions is made using a UV detector.

This report describes the analysis of anions using an inert anion exchange chromatography system with ICSpak suppressor.

LC-4000 HPLC system

Experimental

Chromatographic conditions
Column: Shodex IC SI-90 4E (4.6 mmI.D. x 250 mmL)
Suppressor: ICSpak (4.6 mmI.D. x 100 mmL)
Eluent: 1.8 mM Na₂CO₃ + 1.7 mM NaHCO₃
Flow rate: 1.0 mL/min
Column temp.: 25ºC
Wave length: 215 nm
Injection volume: 100 µL
Standard sample: Anion Mixture (Described below)

Table 1.  The concentration of anion standard solution mixture

Figure 1. Flow diagram

Keywords

Anion Exchange Chromatography, Chemical Suppression, HPLC, conductivity detector, ion suppression.

Results

Figure 2 shows the chromatograms of anion standard solution mixture. 7-component anions were detected.

Figure 2. Chromatograms of anion standard solution mixture using Shodex IC SI-90 4E and chemical suppressor ICSpak (Top: UV detector, Bottom: Conductivity detector, 1: F^–, 2: Cl^–, 3: NO2^–, 4: Br^–, 5: NO3^–, 6: PO4^3-, SO4^2-)

Table 2 shows the detection lower limited values of anions.

Table 2 Detection limit for a range of anions