First time in our lab we are attempting trace element analysis on speleothems. We are using JLs-1 as standard. For major elements we dissolved 6mg sample in 60 ml (10000 x dilution factor). Though major elements were easily measured, trace elements like U and Th went beyond detection limit. The standard used has 0.0287 ppm of Th. For calibration curve, further dilutions may reduce it to undetectable limits.
Are you using Q-ICPMS? I have been doing limestones with 1000 times dilution, and even then it is a struggle for some of the low-abundance traces.
Hallo Shadda,
this is the first time Researchgate notifies me of a question that is really related to my research ;)
I would say, the minimum amount of sample powder you need for a proper TE analysis, naturally depends on the concentration of the different TE in your speleothem.
Is there a specific reason why you use 60 mL volumetric flasks? For my master thesis, I used 7-10 mg powder dissolved in 10 mL flasks and I just bought 2 mL flasks (they are really cute) in order to minimise dilution during sample preparation.
Unfortunately, we haven't measured U or Th in our speleothem then so I cannot say if concentrations would have been detectable using 10 mL flasks. After dissolution the samples were measured without any further dilution.
Best wishes
Arno
Dear Shaddha
you check link below
http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=1217&context=ijs
Regards
Massih
Dear Mrs. Band,
in my opinion it is difficult to show you which way you should direct your thoughts. The reason for that is simply we do not know what type of sediments you deal with. Caves can be filled with carbonate minerals but their may also argillaceous residues from karstification or even APS minerals caused by hydrothermal activity. A varied group of minerals can be expected. On the other hand what is your analytical work aimed at . You mentioned Th and U which make me think of chronological dating (?). Yet I am not sure about. Do you want to make use of U disequilibria ? As long as we do not know these basic items it is for me some kind of poking around in the fog.
Best regards
H.G.Dill
Dear Prof Dill,
Thank you for responding to my question. I was referring to stalagmite sample made of calcite. Also, You were right about our motive of measuring U and Th concentrations. We are planning to date the stalagmite sample in our own laboratory. For which we needed to know the concerntration of these elements. In addition we want to analyze Mg, Sr,Ba and Ca in ICP-MS for paleomonsoon reconstructions. After going through many papers, we have decided to make two sets of dilutions. Meaning, we wil take 10mg of sample and dissolve in 10ml solution. From this stock solution we will extract 1ml and further dilute the sample for Ca and Mg analysis. And use the remaining 9ml stock solution for trace elements directly. I hope my response was not vague and I was able to convey my intentions clearly. Kindly provide your valuable suggestions.
Best regards,
shraddha
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