Record Details
Simultaneous spectrophotometric determination of calcium and magnesium with Arsenazo III
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Simultaneous spectrophotometric determination of calcium and magnesium with Arsenazo III |
| Names |
Shafer, Howard Price, II
(creator) Williams, Max B. (advisor) |
| Date Issued | 1968-04-11 (iso8601) |
| Note | Graduation date: 1968 |
| Abstract | A dual -pH simultaneous direct spectrophotometric method for the determination of calcium and magnesium using Arsenazo III has been developed. An absorption spectra study was made of Arsenazo III and its magnesium, calcium, strontium, and barium complexes at various pH values. This study showed that total calcium and magnesium can be determined at 652 mμ. and pH 8.4; however, only calcium is determined at 652 mμ and pH 4. 1 as the pH 4. 1 magnesium complex has a very low molar absorptivity. The approximate apparent molar absorptivities, in 1 mole ⁻¹ cm ⁻¹, are: calcium complex, at pH 4. 1, 6.3 X 10³, and at pH 8.4, 2.9 X 10₄; magnesium complex, at pH 4. 1, less than 100, and at pH 8. 4, 9. 6 X 10³. The extent that the complexes followed Beer's law was 0 -1.20 ppm calcium at pH 4. 1, 0 -0.80 ppm calcium at pH 8. 4, and 0 -0. 60 ppm magnesium at pH 8. 4. The complexes were found to be stable for at least one day, whereas the reagent was stable for at least 85 days. Several calcium complexing anions and the alkali metal elements were found to not interfere in the determination of calcium, but aluminum (III), iron (III), copper (II), strontium (II), and barium (II) interfere at the 1:1 concentration level at pH 4.1 and /or pH 8.4. A preliminary study was made of an alternate method to determine calcium and magnesium using a combination of EGTA and Arsenazo III. Equations were developed for the direct determination of calcium and magnesium by the dual -pH method and by the EGTAArsenazo III method. A series of synthetic standard solutions of calcium and magnesium were determined using both methods. |
| Genre | Thesis/Dissertation |
| Topic | Calcium -- Spectra |
| Identifier | http://hdl.handle.net/1957/46737 |
