SURVEY ON STUDY OF HEAVY METAL POLLUTION IN CROP PLANTS IN REWARI DISTRICT OF HARYANA

ABSTRACT

100 mg dry powder of plant sample was digested in a mixture of 2 ml 60% perchloric acid (HCIO4) and 2 ml concentrated nitric acid (Conc. HNO3) by heating on a hot plate to dryness. The residue dissolved in 10 ml ammonium citrate buffer pH 8.5 (90 g ammonium citrate dissolved in 1 litre distilled water and made to pH 8.5 with ammonium hydroxide). Similarly, 100 mg air-dried soil was digested in 10 ml of 2N NHO3 and 2 ml 60% (HCIO4) and to this digest; 10 ml of ammonium citrate buffer (pH 8.5) was added. For heavy metal extraction by complexing with dithizone, plant or soil digest was made to pH 8.5 with sodium hydroxide (NaOH) and extracted repeatedly with 5 ml of the purified dithizone solution (100 mg of dithizone dissolved in minimum volume of chloroform (CHCI3), portioning against diluted ammonia, collecting the aqueous dithizone containing layer, acidifying this fraction with few drops of (NH4)2SO4, reextracting the dithizone in chloroform and making the volume to 1000 ml with chloroform to give a final concentration 0.1% dithizone in chloroform). The extracts was than pooled and made to 20 ml with chloroform and absorbance was read at A520 nm. The quantities of total heavy metal was estimated with the help of standards and the calibration curve.

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