I have separate algal and zooplankton samples that I want to have stable isotope analysis of C and N performed on.
The samples were filtered onto 0.4 µm glass fibre filters (GF/F) that were then freeze-dried and stored at - 80 degrees. In error, the glass fibre filters were not pre-combusted or pre-weighed prior to having the zooplankton and algal samples filtered onto them.
Is there a way to still use these samples for stable isotope analysis of C and N? I have read that you can scape the material of the filter paper and then place in a tin foil boat for analysis but don't feel confident in the reliability of this approach.
Hi!
I think the biggest issue you will have have is to not have pre-conbusted the filters. Not having their masses should not be an issue to have d15N, d13C and C:N ratios. It is an issue however if you want to make dry weigth measurements.
The big issue with the lack of pre-combustion is that you may have carbon and nitrogen in the filter that do not come from the plankton (e.g. dust accumulated during fabrication or storage). One way to check for that would be to measure a blank filter (coming from the same pack). If there is a lot of carbon or nitrogen, it is not good, but if it is relatively clean, maybe it doesn't affect your results too much.
Hope this helps!
Nicolas
Nicolas Djeghri Thanks Nicolas.
It is a real shame they weren't pre-combusted (keeps me asleep at night).
I might run several blank filters from the same pack to get an idea of how much they vary.
Thanks for the response!
Hi !
If you get satisfactory results after checking the blank filters, you can use the scraping method for d15N. Just scrape off the layer of filter paper from behind without disturbing the top layer (avoid any contamination while doing so). For d13C, use a part of filter paper if the content is too high after acid fumigation.
Hope this helps !
Prachi
- Badges
- Science topic
- Similar topics
- Psychology
- Emotion