Simultaneous separation of common mono- and divalent cations on silica gel modified with aluminium by non-suppressed ion chromatography with conductimetric detection and nitric acid-15-crown-5 as eluent.
The modification of silica gel with aluminium by a coating method was very effective for the preparation of silica-based stationary phases which acted as a cation exchanger under strongly acidic conditions. However, the separation of common mono- and divalent cations (Li+, Na+, NH4+, K+, Mg2+ and Ca2+) on an aluminium-adsorbing silica (Al-Silica) column was moderate by a conductimetric detection ion chromatography (IC) with strongly acidic eluents. Then, the addition of various crown ethers (12-crown-4, 15-crown-5 and 18-crown-6) in acidic eluent was carried out. As a result, it was found that 15-crown-5 was most effective for the improvement of peak resolution. Excellent separation of these cations was achieved in 20 min by elution with 2 mM nitric acid-2 mM 15-crown-5. The proposed IC was successfully applied to the determination of major cations in various natural waters.
Ohta
K
K
National Industrial Research Institute of Nagoya, Japan. kazuohta@nirin.go.jp
Morikawa
H
H
Tanaka
K
K
D000535:Aluminum / Q000737:chemistry; D002413:Cations, Divalent / Q000032:analysis*; D002414:Cations, Monovalent / Q000032:analysis*; D002852:Chromatography, Ion Exchange / Q000379:methods*; D003217:Conductometry; D043844:Crown Ethers; D004988:Ethers, Cyclic / Q000737:chemistry; D017942:Nitric Acid / Q000737:chemistry; D058428:Silica Gel; D012822:Silicon Dioxide / Q000737:chemistry; D014867:Water / Q000737:chemistry
D002413:Cations, Divalent; D002414:Cations, Monovalent; D043844:Crown Ethers; D004988:Ethers, Cyclic; D014867:Water; C042148:15-crown-5; D017942:Nitric Acid; D058428:Silica Gel; D012822:Silicon Dioxide; D000535:Aluminum