The best  procedure is digestion using the method of Jackson (1958)  of dried root samples, then measure the heavy metals using Atomic absorption spectrophotometer.

you can measure the heavy metals using atomic adsorption and uv-visible spectrophotometer.

Rinse the roots thoroughly to get rid off all metals adsorbed or attached in some way to the outside of the roots. Determine dry weight. Use the dried fraction for total destruction HNO3 or equivalent method). Determine metal concentrations on ICP MS. Calculate back to dry or wet weight as needed.

Thanks a lot Dear Dr Abbas, Dr Ali and DrFreddy

The best procedure is extract using the method of kindle et al. 1997 then measure the heavy metals using AAS

All suggested methods are good. You can also ash the samples and digest the ash. However, how you go about performing digestion and subsequent analysis depends on what metals you are looking for. Nitric acid is good because nitrate salts are very soluble. But you need to make sure that whatever acid you use a) effectively digests the metals in the sample, b) does not cause oxidised metals to form insoluble precipitates. Then when it comes to the analytical method, if you are looking at levels of a few selected metals then AAS is an excellent technique (provided there is no spectral interferencebetween digested metals in the flame, or you do not have an issue with elements forming refractory oxides in the flame, in which case you need to use a nitrous oxide/acetylene flame instead f an air-acetylene flame). If you have many metals to measure or you don't know exactly what metals you are looking for, ICP-MS is the best way. The plasma flame eliminates the problem of refractory compounds forming in the flame, and the issue of spectral overlap is not a problem. You can also analyze for many elements simultaneously. Hope this is helpful.

Please follow the digestion method is this paper and then measure your samples with AAS. It is such a new reference 2009.

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132014000300018

Kind regards

Dear Dr Yadav

First of all try to rinse the roots thoroughly due to determine only the heavy metals which are absorbed by the roots . 

Use the wet digestion method by concentrated Nitric Acid and Per chloric acid ( follow the protocol of AOAC 2000) . Determine metal concentrations on AAS or  ICP MS. 

You can follow the simple method from these papers:

https://www.researchgate.net/publication/308341036_Potential_of_Echium_ameonum_Fisch_Mey_in_Removing_Heavy_Metals_from_Pharmaceutical_Effluent

https://www.researchgate.net/publication/307141379_Removal_of_Selected_Heavy_Metals_from_Pharmaceutical_Effluent_by_Aloe_Vera_L

https://www.researchgate.net/publication/301842737_BPJ_Vol_9_No_1_p_169-175

Best regards

Parisa Ziarati

Article Potential of Echium ameonum Fisch & Mey in Removing Heavy Me...

Article Removal of Selected Heavy Metals from Pharmaceutical Effluen...

Data BPJ Vol 9 No 1 p 169-175