Effects of cetylpyridinium chloride and zephiramine on spectrophotometric determination of molybdenum (VI) with gallein
1973 Volume 22 Issue 3 Pages 270-275
Details
1973 Volume 22 Issue 3 Pages 270-275
Gallein reacted with molybdenum (VI) to form water soluble various complex in the presence of excessive species of quaternary ammonium salt. Gallein reacts with molybdenum (VI) in the presence of cetylpyridinium chloride (CPC) to form a water soluble, red-purple chelate. The absorption maximum was at 590 nm, and the absorbance was constant over the pH range from 1.0 to 2.7 adjusted with HCl buffer solution. The complex has a composition of 1 : 1.5 in the excessive CPC.
The molar absorptivity is 4.9 × 104 at 590 nm and the sensitivity is 0.0020 μg Mo/ml for an absorbance of 0.001.
The effect of diverse ion on the absorbance of the complex was examined. Antimony, tin, vanadium, and tungsten must be avoided. Antimony could be masked by an addition of 0.05M EDTA. Vanadium could be masked by an addition of 0.05M EDTA and 0.1 g KF.
The ternary complex system between molybdenum (VI), gallein and zephiramine formed a water soluble blue chelate. The absorption maximum was at 620 nm, and the absorbance was constant over the pH range from 1.0 to 1.5 adjusted with buffer solution. The complex has a composition of 1 : 2 in the excessive zephiramine.
The molar absorptivity is 5.2 × 104 at 620 nm and sensitivity is 0.00185 μg Mo/ml for an absorbance of 0.001.
The effect of diverse ions on the absorbance of the complexes was examined. Tin, chromium, titanium, and silver must be avoided.
The both complex were proposed for the spectrophotometric determination of microgram amounts of molybdenum. The calibration curve at 590 nm (in the presence of CPC), and at 620 nm (in the presence of zephiramine) was quite linear for 03.5 μg/ ml molybdenum.
The recommended analytical procedure was as follows. To a 25 ml volumetric flask was added the sample solution containing less than 88 μg of molybdenum (VI) /25 ml. Then 7 ml of HCl (pH 1) solution, 2 ml of 1 × 10 -3M ethanolic gallein solution, and 2.5 ml of 2.0 × 10 -2M CPC or zephiramine solution were added to sample solution. The whole was made up to the mark with distilled water.
After it was allowed to stand for 20 minutes at 25°C, the absorbance was measured at 590 nm or at 620 nm against the reagent blank.
