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
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
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: 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 |