heavy metals from powder particles of roots, flowers and seeds
ICP is better because
1. It is multi element analysis
2. Has high sensitivity and detection limits
3. Can analyze elements over a wide concentration range
4. It requires minimal sample preparation
5. It is faster
Githmi Meegahawatte In terms of superior sensitivity, ICP-MS has lower detection limits compared to AAS. This means it can detect much smaller quantities of heavy metals, which is necessary for analyzing biological samples like plant parts where heavy metal concentrations might be low.
ICP-MS could be much more benificial regarding this case. You can follow the provided link to know more better about this.
https://www.researchgate.net/publication/378108861_Waste_biomass_derived_chitosan-natural_clay_based_bionanocomposites_fabrication_and_their_potential_application_on_wastewater_purification_by_continuous_adsorption_A_critical_review
Yes ICP-MS, but you need good quality electricity and argon. That is it's both expensive to buy and run. You also need access to the company's engineers to fix problems at a reasonable cost.
The question raised about 'powders' comes down to digestion techniques needed before sample introduction to the measuring equipment. The suggestion of CRMs is a good one for validation, but they too are expensive for QC! Reasonable quality reference materials are available for QC through various providers, and tight QC is critical to consistent good performance. You might consider making your own QC samples. It is labour intensive and you need a small containers and a chest freezer to ensure long-term integrity.
The best instrument for detecting heavy metal content is ICP-MS, especially for low concentrations, for example in the general population.