Sample identification number. P.O. number Type of analysis requested, i.e., low res., exact mass, etc. Proper sample analysis request form - only 2 possibilities exist. Samples will be returned in these containers if thus shipped. Not recommended - envelopes or other soft containers.
Breakage often results.
These are the easiest to store and sample. Preferred label is paper taped to vial. Anything greater than 2 ml capacity.