Hello Dang,

You can freeze them or use ethanol. Rinse them with sea water before analysis if preserved in ethanol. Do not use formalin.

Thank you Luis very much.

Can i use ethanol then i must sorting them before analysis? because the specimens include zooplankton,.

You can sort your samples once preserved in ethanol.

Be aware that ethanol may alter the C signature of your samples (see for example : Hydrobiologia 632(1) :297-308, 2009). You may have some transportation restrictions because ethanol is considered a dangerous good/hazardous material by IATA and DOT. I would recommend the use of dry ice.

Maybe the best method is to freeze drying (lyophilization) your sorted samples. Another option could be dry them in a 60-70°C oven and then send your samples with a cold pack batteries or dry ice.

Hi Dang,

You could use ethanol or freeze them. If you use ethanol you will have to dilute it with distilled water at 50-55%, because larvae are so fragile and they could dehydrate with pure ethanol. You could freeze them as well.

Laura

Hi Dang,

I have used this method that is the SOP for biogeochem advisor for my research. Always were gloves to avoid contaminating your samples. I would always go from an iced/refrigerated field sample to a -20C freezer for holding the sample until you are ready to prep it. I would also advise trying to start with the same container that you will be archiving the remainder of sample in so that you are subsampling for stable isotopes into just one smaller vial. Less moving things around reduces the chances for contamination.

We freeze-dry tissue and faunal samples in clean, baked scintillation vials for 72 hours, and then grind each sample in clean homogenizer vessel. Aliquot ~20mg of each sample into clean, baked small vials. (When I say baked that means that these were already acid washed and rinsed with DI water 2X, and covered with foil before we bake these in a muffle oven at 425 Degrees F for 4 hours at a 30 degree per minute ramp rate). The remainder of the sample remains in the clean, baked scintillation vials you started with and then you can refreeze this sample with a baked foil seal between the cap and the vial.

Dry aliquot samples in 60°C oven for 24 hours, then add 10% Trace Metal grade HCl acid (drop by drop) until sample stops bubbling. We then place the SI samples(vials) in aluminium pans (like a small loaf pan) and cover with the pan with a slightly tented sheet of baked aluminium foil before placing the pans on a hot plate set to ~60°C, which is inside a fume hood. This is done to to evaporate the acid. Repeat this acidification step if the sample continues to bubble after dropping acid on a small subsample. This step gets rid of the calcium carbonate.

Dry the samples on the hot plate for several hours (6-12) and then back to the drying oven for several more hours (12-24). Homogenize samples with clean, baked small glass rods or scupulas that have been cleaned with 10%HCl, rinsed with DI water and dried. Finally, you are ready to put the sample in the weighed tin capsule, mass it on the microbalance and and note down weight. Again this is done with an acid washed scupula, which is cleaned between each sample.

Make yourself some spreadsheets/templates for track you samples during the stages of prep and keep a overall spreadsheet that includes your data/measurements from the beginning to the end.

These procedures are from the Geochem lab of Dr. Ai Ning Loh at Florida Gulf Coast University, and I have used them to process a couple hundred samples and have had consistent results. Good luck!

I forgot to mention that these are the procedures for tissue, sediments and benthic microalgae.

Be sure to store the processed SI samples in the tin balls in a shipping container (96 well plate) that is sealed with parafilm in a dessicator until you ship them andit will keep them in place and avoid having them moving around and switching locations before they are read.

Thank you so much for everybody, that is useful information .

Hello,

Adding HCl is necessary when samples contain calcium carbonate (sediment, bone, shells, plankton, whole crustaceans, macrophytes with epiphytes,…), as it is enriched in 13C as compared with proteins. However, acidification modifies the δ15N values inconsistently and hence you have two split each sample in two aliquots: one treated with HCl for δ13C and the second one (without HCl) for the δ15N. This increases the cost of analysis and is not always necessary. For instance, there is no reason to add HCl when analysing muscle, liver or other soft tissues. I’m unsure about the amount of calcium carbonate in your fish larvae, but if very low, there is no need to add HCl and duplicating the cost of the analyses.

First you need separate by groups (fishes, crustaceans, ect) or if it is possible species level. After it you can frozen the samples. However I recommend to dry the more quickly as possible.

In fact, if you need send the samples by mail, the safest form is dry (pulverized sample). Sometimes post companies do not receive packages with flammable liquids (ethanol) or corrosive liquids.

I recommend freezing, freeze drying or oven drying in that order. If none of these are possible, use 70% ethanol but have the lab decant, rinse and dry before homogenizing for isotope analyses.