Simultaneous determination of alkali, alkaline earths and ammonium in natural waters by ion chromatography

Abstract

An ion chromatographic method has been developed for the determination of alkali (Li + , Na + , K + ), alkaline earths (Ca 2+ , Mg 2+ , Ba 2+ , Sr 2+ ) and ammonium ion in waters. The usual difficulties encountered during traditional cation-exchange separations (incomplete resolution for Na + and NH 4 + present in disproportionate concentration ratios) have been overcome tuning the selectivity of the separation by the introduction of 18-crown-6 ether in the mobile phase using an IonPac CS12A (15063 mm id) column. After a detailed study of the effect of mobile phase components on separation, a gradient elution from 26 mM methanesulphonic acid (MSA) with a step change at 9 min to 60 mM MSA (0.5 mM 18-crown-6) provided the required baseline separation for the eight selected analytes. The method developed provides the advantage of the determination, in the same analytical run, also of strontium and barium, which is usually performed by spectroscopic techniques. Within-day and between-day repeatability have been assessed, observing between-day RSD included between 0.3 and 1.8% for retention times and 0.6 and 7.2% for peak areas. The method has been finally tested for the analysis of water samples of different provenience (well, tanks, water system) and results compared with those obtained by the laboratory in charge of the control of drinking water for the city of Torino (Italy).

The Challenging Role of Chromatography in Environmental Problems

“…By using a concentration of 18-crown-6 ether as low as 0.5 mM with a methanesulfonic acid-based eluent, Bruzzoniti et al [20] recently achieved the separation of Li ? , Na ?…”

Functionalized polymeric stationary phases for ion chromatography

“…Since IC offers many possibilities of application, it is used in different branches of current analytical chemistry [4][5][6]. In recent years, the number of ion-exchange materials that have been developed for IC has increased tremendously [7,8].…”

Investigation of the thermal behavior of new silica-polymer anion exchangers

“…They are often applied as stationary phases in chromatography, including also ion chromatography (IC) [1][2][3]. Since IC offers many possibilities of application, in recent years the number of developed ion-exchange materials has increased dynamically [4][5][6][7]. Most stationary phases currently used for separation of ionic compounds are based on organic polymers as well as silica gel.…”