What is the protocol to estimate the heavy metal analysis in soil organisms using AAS? I have seen aqua regia method in a few papers while others mention nitric acid method for digestion. Should I digest the samples after freezing or digest the samples after oven drying?
Dear Sir. Concerning your issue about the estimation of the level of heavy metals in soil organisms. The concentration of heavy metals (Fe, Zn, Cd, Pb, Ni, Cu, Mn and Cr) was determined using atomic absorption spectroscopy (AAS) following the procedure described by Akoto et al. (2008) and the evaluation of heavy metals’ availability was performed using Inductive Coupled Plasma Atomic Emission Spectrometry (ICP-AES) after extraction with CaCl2, as described by Galfati et al. (2011). The results were compared with Polish regulations for the maximum concentrations of heavy metals allowed in soils. Statistical analysis of the results was performed using Statistica software (StatSoft, USA), Pearson correlation (r) was applied to test relationships between the number of microorganisms and soil pH and heavy metal concentration at the level of significance equal to 0.05. I think the following below links may help you in your analysis:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3538006/pdf/128_2012_Article_869.pdf
http://www.agriculturejournals.cz/publicFiles/154713.pdf
http://onlinelibrary.wiley.com/doi/10.1002/clen.201700617/abstract
http://www.scielo.br/pdf/bjm/v43n4/47.pdf
Thanks
Hi there
I dont find it useful to direct you to any protocol if you havent specify what you want to achieve
You need to divide your methodology in two parts: Sample preparation and analysis (AAS).
Sample preparation (Extraction) has to be matched with your objectives, for example:
- what metals are you extracting, some metals are easier to extract than others, some even require HF for total extraction
- What equipment you have available: microwave assisted digestion, normal hotplate and vessels, etc
- Do you have appropiate controls available?, such as CRM for your specific metals and specific matrix. If not you will have to perform spiking experiments to know your extraction efficiency
Once you know all of this, you may start looking at protocols, before is just not science
I am looking for a protocol for sample preparation for heavy metal analysis using AAS. Apart from HF total extraction method, which are the other methods? In a few papers I have seen aqua regia method for sample dogestion but others mention nitric acid digestion method? Which one among these is most preferred for estimation of Lead, Cadmium, Chromium and iron?
Hi. Gopakumar,
Thanks for interesting question.
The common digestion protocol for the determination of metals in soil include the following;
1. The aqua regia method
2. digestion of samples in a mixture of HF-HNO3-HClO4-H2SO4
3. digestion of samples in HNO3-HClO4 mixture
For details of the above methods you can consult the following literature;
Hseu, Z. Y., Chen, Z. S., Tsai, C. C., Tsui, C. C., Cheng, S. F., Liu, C. L., & Lin, H. T. (2002). Digestion methods for total heavy metals in sediments and soils. Water, Air, & Soil Pollution, 141(1), 189-205.
Regarding the appropriateness of the most common methods (aqua regia digestion) you can consult the following interesting literature;
Chen, M., & Ma, L. Q. (2001). Comparison of three aqua regia digestion methods for twenty Florida soils. Soil science society of America Journal, 65(2), 491-499.
It really depends. If you use total digestion method (microwave system plus acid mixture including HF) - you will find a total content that is interesting for geologists only probably. Usually it is interesting to find a mobile form which means the amount that can be extracted by plants and by water in natural conditions. In this case different extragents could be used including Mehlich extraction, acetate buffers, ammonium carbonate etc - depending on soil type and approach those should be addressed to agronomists, not chemists.
Though all matrices (with exception of ammonium carbonate) are easy for ICP-OES.
Also it should be noted the above is dealing with soil analysis, not soil organism only. Obviously soil organisms should be extracted from soil and then digested as any biological tissues.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Atomic, Molecular and Optical Physics
- Atoms