Am I correct in thinking that it is as simple as drying, powdering and weighing all samples, then wrapping in aluminium or tin foil, popping into a labelled screw top container and that's it?
Samples can be removed from the field collection site, rinsed (should I use RO/DI water or seawater for samples of marine origin?) and be in a drying oven within a couple of hours of collection. Once dried, grind into powder, weigh and wrap?
Samples will need to be transported for 30+ hours (international flight) so freezing or any form of volatile liquid is a definite no-go.
Is there a "lab grade" foil, or can general aluminium or tin foil for home use be used, then transfer to tin capsules at a later date?
Sorry if this question seems a bit dumb, there is lots of methodology out there but the basics are often omitted and I don't have direct access to anybody for training and questions at the moment.
Drying to a dry mass will be enough. If you want to powder the samples, you will need to dry them again after powdering. Dried samples need to be stored in a dry, tightly closed container (just like lyophilised food). This should be enough to prevent from C loss or N loss/addition caused by microbial action. General foil cannot be used - it contains considerable amount of C.
Kind regards,
Michał Filipiak
Thank you! Does the container need to be any specific material - for example, plastic or glass screw top, to reduce contamination?
Just to be sure: collect sample into plastic container. Return to lab, rinse with RO water, oven dry, add to storage container and leave well alone until I get back to my usual lab space? or does any form of rinsing sediments off ruin the viability of a sample?
You are welcome! Specific container is not needed. Rinsing is ok.
You need to take into consideration boiling point of CO2 (approx. 75 °C) and NO-s (approx. 152 °C). If you exceed these temperatures, you will loss some C and N from your samples. Thus vacuum oven is the best solution.
Thanks again. So many conflicting methodologies in papers and online and often omitting the simple basic instructions!
Mark,
One of the most important things to remember is to avoid contamination of your samples. Keep all your instruments clean and work in a clean lab. Always wear gloves when handling samples so your skin cells do not contaminate.
Tom
Thank you Tomas, I will be changing gloves between specimens. Some online lab schedules recommend all sorts of exotic chemicals for cleaning dissection gear with between samples, including fun things like methanol.
I was just going to clean instruments with ethanol, then distilled water and blot dry.
Have managed to obtain some of the proper tin boats for completed, powdered samples.
Cheers for the advice everyone.
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