After adsorbing heavy metals (e.g., Pb, Zn) on microplastics (e.g., PP, PE), and then drying the spiked-microplastics, how long can they be stored before quantification (e.g, AAS, ICP-OES, ICP-MS)?
Analytical chemistry is a very new field for me. Thank you in advance.
Dear Dr Amelia, very nice question, hope the references be helpful in this regard:
1- Industrial solid waste for heavy metals adsorption features and challenges; a review ( Article Industrial solid waste for heavy metals adsorption features ...
2- Article Lignocellulose-Based Superabsorbent Polymer Gel Crosslinked ...
specially the parts of 3-3: Effects of Desorption Agent Concentration and Effects of Desorption Temperature,.....
My Best wishes
A very interesting question. I would think that once dry, they would last indefinitely unless handled frequently. The issue is contamination, primarily from the containers you are using to store the microplastics in. e.g. yellow caps have (in the past) contributed Cd, I have seen Pb from PTFE liners etc, so lots of blanks and clean handling procedures are essential. (Zinc from gloves is a big issue too).
What sort of mass of microplastic are you dealing with - a few mg or several grams at a time?
I would suggest that if the latter, you can store samples in (clean, obviously) polypropylene sample tubes (typically 15 or 50 ml sizes) and expect minimal transfer from the bulk sample to the sample tubes. If you have only a few mg, then surface area of sample vs tube may come into play.
How do you propose to analyse the sample for metals? If acid digestion, you may prefer to store in the digestion tubes which probably requires glass for the obvious reason that you can't digest plastic sample in plastic tubes. BUT metals will leach from the glass structure as well. (Also note that the acid supplied in glass bottles has leached metals from it's container as well. There are non-glass options). Perhaps PTFE microwave tubes can be used, but these are bulky and not really designed as storage vessels, and can suffer carryover contamination.
Perhaps laser ablation-ICP-MS would avoid digestion issues and minimise handling issues as well. You'd have to speak to someone else for details on that.
Nice question, once an adsorption occured, there is formation of complex between the adsorbent and the solutions of the heavy metal.
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