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Comparing suppressed and non-suppressed ion chromatography

Suppressed ion chromatography with conductivity detection is a powerful and sensitive technique to analyse charged ionic species, especially anions of strong acids. The chemically regenerated membrane suppressor Xenoic® XAMS can enable analysis of such anions down to levels of a few microgram per litre (part per billion, ppb).

This example highlights the strong impact of using a robust suppressor to enable more sensitive quantification of lower amounts of anions. The setup with suppressor reduced the background and noise by more than 99%, while also enhancing the signal intensity. Together this resulted in a 200-fold improvement in signal-to-noise ratio and estimated detection limits for nitrite, compared to non-suppressed ion chromatography under otherwise identical conditions.

Ion chromatography of five inorganic anions with and without XAMS suppressor formatted

Comparison of suppressed (solid line) and non-suppressed (broken line, offset by -1000 µS/cm) ion chromatography on a Shodex IC SI-50 4E column (250×4 mm) using an eluent containing 5 mM NaOH in water, pumped at 1.0 mL/min at 25 °C from an EQAX-B1 eluent bottle (1 L). Eluent pumping and conductivity detection by Metrohm 761 Compact IC. Background reduced by XAMS suppressor with ASUREX-A200 automatic regenerator to 1.6 µS/cm (from 1022 µS/cm), thereby also reducing the noise (average of seven determinations peak-to-peak, each during one minute) to 2.6 nS/cm (from 590 nS/cm). Injection of 20 µL of fluoride (5 ppm), chloride (10 ppm), nitrite (25 ppm), bromide (20 ppm), nitrate (25 ppm) in water.

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