Anion Analysis using Ion Chromatography with Chemical Suppression

March 16, 2021


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


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

Anions Concentration [mg/L]
F 0.2
Cl 0.3
NO2 0.5
Br 1
NO3 1
PO43- 1.5
SO42- 1.5

Figure 1. Flow diagram


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


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: PO43-, SO42-)

Table 2 shows the detection lower limited values of anions.

Table 2 Detection limit for a range of anions

Anions Concentration [mg/L] Injection volume [ng] UV detector Conductivity detector
S/N=3 [µg/L] S/N=3 [µg/L]
NO2 0.5 50 0.89 1.46
Br 1 100 8.39 1.50
NO3 1 100 1.33 1.34
F 0.2 20 0.32
Cl 0.3 30 0.40
PO43- 1.5 150 3.67
SO42- 1.5 150 1.45

About the Author

Chromatography Group