Question

Say you are provided two samples containing an unknown concentration of calcium. One sample is a liquid and one sample is a solid (ie. calcium tablet). What analytical technique would be most efficient for chemical analysis and why? Take into consideration LOD, convenience, precision, accuracy, etc.

Answer 1

Analysis of calcium

Liquid sample : a sample of calcium containing compound in liquid can be analysed by chemical means. Say we react this solutioin with a fixed volume of HCl of known concentration. After complete reaction, we back titrate the excess HCl in solution with standard NaOH solution. The difference would give us the amount of HCl rected with Calcium and thus amount of calcium resent in the solution. A series of titrations of this reaction is perfomred to get accurate and precise value of calcium eliminating any possible errors.

Solid sample : A sample of calcium containing sample in solid form can be abalysed by atomic absorption technique. The sample is first dissoved in say HNO3 and diluted with water. The resultant solution is injected into atomic absorption spectrophotometer to determine the amount of calcum in solution. A series of dilution of solution is performed and analyzed for calcium to get an accurate and precise value for the amount of calcium present in the solution and thus in the solid.