Determination of calcium in serum:
A classical AAS determination of calcium in serum is carried out through calibration method wherein, a calibration plot is acquired by measuring the absorption of features radiation (422.67 nm) for a series of standard solutions of calcium in a same matrix. An air-acetylene flame is used along with a premix burner. The normal calcium content of serum is commonly about 100 ppm and it is determined through diluting the sample 1:20 with 1% SrCl2 solution. Therefore, a typical sample would contain about 5 ppm of Ca. Thus, an equivalent amount of sodium and potassium are added to the standard solutions. The plot is then used to determine the concentration of the given sample.
It required to be mentioned in which the effects of instrumental parameters and of phosphate and aluminium ion on calcium absorption are to be suitably accounted for an effective determination. Instrumental parameters like as burner height and fuel air ratio might be studied to optimise the experimental conditions of flame height and fuel gas pressure.
Same the effect of organic solvent like as ethanol might also be studied. The effects of interferants is borne through using 5 ppm each of phosphate, sodium and aluminium solutions
In an alternative determination, using the technique of standard addition a series of calcium standards of 0, 2.5, 5, 7.5, 10 and 15 ppm are prepared from the 50 ppm stock solution and SrCl2 is added to standards and the unknown to gives a final concentration of 1%. The standard addition absorbance calibration plot is then prepared and used for the determination of the concentration of analyte sample.