I have samples of leaves, roots and soil highly enrichment but I want to dilute the concentration of 15N in order to be able measure them in the isotope ratio mass spectrometry.
Hello Maria, I did somtimes similar things with high enriched nitrate samples. For that I mixed my sample with a not enriched nitrate solution with the same concentration, Then I measured the mixed sample and calculate by a normal rule of three the delta15N of the enriched sample. I think you can do the same, mixing your sample with a known standard like acetanilid. But I never did that, but for nitrate it works. Tina
Yes, i agree with Tina. I did the same with enriched amonium nitrate mixing it with a non enriched solution applying the diluition equation for the calculus (you just need to know the final concentration).
After mixing calculated amount of normal leaves and roots to enriched sample, the leaves and root must be oven-dried (80 degrees C, 24 hours). Dried samples are ground to talcum powder consistency (250 micro-m or less) using a ball mill. Thorough sample homogenization in the grinder stage is required, to make certain that the tiny subsample taken for analysis is representative of the total sample.
After mixing normal soil with enriched sample, it should be air-dried and carefully homogenized. Soil samples are ground for 30 min in an automatic mortar, and after grinding, 96% of the soil sample could pass a 125- micro sieve and 48% a 62- micro sieve (fine particles). Homogeneity is defined as a substance of uniform structure or composition throughout the entire sample matrix. Three things to consider when processing samples for uniform composition are sample particle size, texture and purity.
Hi again,
Elisabetta Tomé, Which is the dilution equation for the calculus? Because I would not like to have a high enrichment in the final mixture, then I would like to know in advance more or less how much mg I have to weight up from enriched and not enriched samples.
Thanks
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