Be sure that your samples are completely dry. Water can affect our instrument and the analysis, and the resulting data can be unreliable.
Samples must be ground to a fine, homogeneous powder. This ensures that the sampled aliquot, which can often be very small (e.g. tenths of a milligram), will be a complete representation of the entire sample.
Try your best to constrain the carbon and nitrogen estimates. This ensures that when you weigh your sample you will have an optimal amount of carbon and nitrogen.
We must be notified for special procedures such as acidification of samples (filters or solid samples).
If acidifying samples, then be sure to use silver capsules.
Nicely wrapped samples will be tight and secure. Avoid edges sticking out or flat configurations, as they can get caught in the autosampler and create serious problems (please see pictures at right for example).
Please tell us if the sample is isotopically labeled!