| As stable isotope applications become more
widely used, the variety of sample
types
that come to us at CSL increases as
well.
Because our main concern is to provide
the
client with the most accurate measurement
possible, we want to insure that sample
acquisition,
preservation, preparation and shipping
will
not alter the isotopic content of the
material.
With this in mind, we are eager to
consult
with the client at an early stage of
research
to determine the best methods to apply. In general, organic matter submitted for analysis should be dried and ground to a fine powder. Biological tissue in particular can be quite variable in its composition on the scale of milligrams and should be milled to the consistency of fine powder. CSL can provide some assistance in this regard if the equipment is not available to the client, although there may be a small preparation charge in some cases and the analytical times may increase. Although our analytical sensitivities are always increasing allowing us to work on smaller samples, the possibilities for contamination and sample loss during handling increase with decreasing sample size. For this reason, it is advisable that sample quantities follow the guidelines given in the analytical pages when possible. Better to return unused sample than not send enough for adequate analytical precision. Liquid samples submitted for hydrogen and/or oxygen analysis should be tightly sealed to prevent any evaporation during shipping. Refrigeration is not necessary if samples are well sealed. The isotopic content of water can change dramatically with evaporation and the effect is more pronounced with the decrease in sample size. Eventhough analysis can be performed on very small samples, it is better to send several milliliters when possible to avoid fractionation. The quantities suggested on the analytical pages are given with this in mind. If there are any questions concerning the size, preparation, preservation or shipping of samples, we encourage you to call or email us for advice. |
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