Submission of Proposal under Star College Scheme

Standard Preparation:
Place 1.249gm A.R. calcium carbonate in approximately 50ml H₂0, adding dropwise concentrated hydrochloric acid until calcium carbonate is dissolved (should take about 10ml). This will give 500 ppm stock calcium standard.The stock solution should be diluted to give standards of 2.5, 5.0, 7.5 and 10 ppm Ca²⁺


Sample Preparation:
Place 4gm (accurately weighed) of milk in a dry silica crucible. Ash sample at 500-525°C oven. When cool, dissolve ash in 5ml of 1:4 diluted concentrated hydrochloric acid. Transfer to 100ml volumetric flask; make up to mark. Filter through Whatman filter paper, pipette 50ml of filtrate into 100ml volumetric flask. Add 2ml of 10% lanthanum chloride. Make up to mark with distilled water.


Method:

1. 
   Spray reagent blank, set zero
   
2. 
   Spray 10 ppm standard set full scale
   
3. 
   Reset zero
   
4. 
   Spray intermediate standards, note readings, construct calibration curve
   
5. 
   Spray test samples and note readings
   

This gives you calcium in parts/million of calcium for milk. If percent calcium required multiply Ca²⁺ ppm sample reading by 0.025 = percent Ca²⁺ in milk. Normal level for milk is approximately 0.11%.


Result:
The Ca content in given milk sample is-----------ppm.
Project: 7
Aim:
Extractive Spectrophotometric determination of Nickel using dimethyl glyoxime.
Theory: Dimethyl glyoxime gives a scarlet red precipitate with nickel in alkaline medium. Nickel(II) dimethylglyoximate is slightly soluble in chloroform and other organic solvents. Since the solubility of Nickel(ll) dimethylglyoximate in water is much less than in chloroform, small amounts of nickel can be effectively be extracted. The optimum pH range for the extraction of nickel complex is 7 to 12 in the presence of citrate. The nickel complex in chloroform absorbs at 366 nm and can be determined spectrophotometrically.


Requirements:

1. 
   Standard Nickel ion solution : Dissolve 0.135 g of nickel ammonium sulphate (A.R.) NiSO4.(NH4)2SO4.6 H2O in small quantity of distilled water and dilute to 1 dm3 in a standard measuring flask. 1 cm3 of this solution contains 20 vg of Ni(II).
   
2. 
   Dimethyl glyoxime reagent: Dissolve 0.500 g of dimethyl glyoxime in 250 cm3 of ammonia solution and dilute to 500 cm3 with distilled water.