Application of a stopped-flow time-difference technique to spectrophotometric determination of ultratrace levels of phosphate

✍ Scribed by Ken-Ichiro Kanaya; Keitaro Hiromi

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 481 KB
• Volume: 203
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(87)90005-5

✦ Synopsis

Optimum conditions, interfering substances, and comparisons with other methods are described for a spectrophotometric method for phosphate, which is based on the stopped-flow technique and involves recording the progress curve for formation of the colored complex of 12molybdophosphate with malachite green. Linear calibration plots were obtained for phosphate in the ranges 5-55 and 100-1000 M 1 -I. The sensitivity and the running speed of the method crucially depend on the sulfuric acid concentration.

The positive interferences of several anions, especially arsenate, thiosulfate, stannate, tungstate and iodide, are significantly less than in conventional methods. Results for total phosphorus in several foodstuffs agreed with results obtained by a molybdovanadophosphoric acid method.