Determination of traces of calcium and magnesium in rare earth oxides by flow-injection analysis

✍ Scribed by Duong Thanh Thuy; Dini Decnop-Weever; Win Th. Kok; Pham Luan; Tu Vong Nghi

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 586 KB
• Volume: 295
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(94)80345-5

✦ Synopsis

Flow-injection analysis has been applied for the determination of traces of calcium and magnesium in rare earth oxide samples. The method is based on the fluorescence of the calcein complexes of calcium and magnesium in a solution with high pH. The analyte ions are separated from the rare earth ion matrix on an in-line ion-exchange column. Matrix concentrations up to 500 mg 1-l of rare earth ions can be used. To discriminate between calcium and magnesium, 8-hydroxyquinoline is used as mashing agent for magnesium and EGTA for calcium. Without masking agent the sum of calcium and magnesium is obtained. The relative standard deviation of the peak height for 25 pmol I-' calcium was 0.4%. The lower limits of determination are 2 pmol 1-l or 0.1 mg g-' in the rare earth oxide for calcium and 1 pmoll-l or 0.04 mg g-* for magnesium. Results obtained with the proposed method agree well with inductively coupled plasma atomic emission spectrometric results for a raw rare earth oxide sample