Best practise for procurement when final unit amounts are unknown?

We are working with a chemical lab to synthesize custom experimental chemical substances for research purposes. Because they are doing synthesis the first time, it’s not possible to know precisely how much of the final amount in grams will there be. So we can place a purchase order for 10 grams, but final amount may be 10g, 9g, 10.5g. if it’s packed into 100mg vials, then final amount can be 100, 90, 105 vial units.

I see after I submit a purchase order, I can’t edit it. Also, if I submit a purchase receipt with e.g. 9g when purchase order had 10g, then I see “to receive” status of the PO.

what could be a good solution? Seems like erpnext isn’t fit for this purpose at the moment.

@rmehta ?

@sagdiyev ERPNext have issues with non-deterministic quantities, and I believe it will stay as it is!

The unique possible solutions I can see for your case is

Create 2 different products, one for buying, another for stocking.

The buying product is purchased by ‘Unit’.
The stocking is managed by grams.

When you receive the product in Unit, make an stock entry of the type repack, to transform into the product managed by weight, and enter how many grams, that unit have been transformed into.