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1358674 
Journal Article 
Determination of arsenic and phosphorus compounds in groundwater with reduced molybdenum blue 
Stauffer, RE 
1983 
Yes 
Analytical Chemistry
ISSN: 0003-2700
EISSN: 1520-6882 
HEEP/84/01628 
55 
8 
1205-1210 
eng 
HEEP COPYRIGHT: BIOL ABS. Chemical studies were made to optimize reduced molybdenum blue for As and P determinations in chemically diverse groundwaters. Phosphate strongly catalyzed the development of the As (V) molybdate complex; increasing H+ or H+:Mo retarded complexation, but the effect was greater for the potentially interfering silicomolybdate complex. The oxidation of As(III) to As(V) by iodate partially inhibited the subsequent color development of silica. Iodide had no effect. F- partially suppressed silica color development, probably because of competitive Sl-F compexing at low pH. The molybdate responses of As(V), P and SiO2 mixtures were not color additive. Optimum reaction conditions were H+ = 0.30 N; H+:MO = 88 for As and P determinations in the presence of silica. Silica was an important analytical interference for the lower H+ and H+:Mo conditions recommended by several population procedures.