Solid-phase extraction of the chromium(III)-diphenylcarbazone complex prior to ion-pair chromatography and application to geological samples.
A method for the pre-treatment of acid samples prior to ion chromatography is described. In a strong acid medium, Cr(VI) oxidizes diphenylcarbazide, the resulting products forming a stable complex which can be transferred in a methanolic medium by solid-phase extraction using polyethylene as sorbent. This methanolic sample solution can be injected directly into a chromatographic system with a silica-based column. The separation and determination of the chromium complex can be performed by HPLC-using a mobile phase of 15% (v/v) acetonitrile containing 1 mmol/L tetrabutyl ammonium hydroxide (TBAH). The detection limit is estimated to be 2 microg/L chromate and the linear range is at least 0.05-2 mg/L chromate.
Tian
S
S
Institut für Anorganische und Analytische Chemie, TU Clausthal, D-38678, Clausthal-Zellerfeld, Germany.
Schwedt
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G