linking blanks to samples

[kmexter]

The blank samples (replicate = "blank") need to be directly associated with samples that they "belong" to. So we need to create a new entry in the ontology and "property" in the ttl files for this ... maybe?

• a blank will need to be a special type of sample - are we doing that now? currently it is a "blank" replicate type - have we formalised this definition in our emo bon vocab?
• A blank is associated with an event because it has the same event ID, but in fact a blank should be associated with samples - there being more than one sample for an event. For water, a blank also has a size_frac_low in its mat_samp_id and this is what can be used to associated the blank with a "real" sample. For sediment it is both the size_frac_low and the comp_samp that should be used to make that association, however as the size_frac_low is often "NA" we have to have a joint think about this to avoid associating blanks incorrectly with more than one sample. For arms the event id should be enough to make the association, as a blank is taken for a single arms unit at a single time

This is so that if someone wants to find a blank for a certain sample via our triples, they can say "give me the blanks for this sample"

[laurianvm]

see description #45