The Pathfinder 2 alchemist class can prepare alchemical items if they have the item's formula in their formula book. However, the class features never explicitly say that the alchemist needs to read the formula book, or have the formula book nearby, when crafting these items during their daily preparations.
You can use this feat to create alchemical items as long as you have the items’ formulas in your formula book.
... choose an alchemical item of your advanced alchemy level or lower that’s in your formula book ...
You create a single alchemical item of your advanced alchemy level or lower that’s in your formula book...
As a point of comparison, the wizard class explicitly requires that wizards must study their spellbook daily in order to prepare spells. So a wizard can't feasibly go adventuring without it.
At 1st level, you can prepare up to two 1st-level spells and five cantrips each morning from the spells in your spellbook...
You start with a spellbook worth 10 sp or less, which you receive for free and must study to prepare your spells each day.
But the alchemist class has no such wording. Taken literally, this would mean that the alchemist can prepare items as long as (1) their formula book exists somewhere and (2) the item's formula is written in the formula book. They could leave their 1-bulk formula book in a safe location and go adventuring without penalty.
In terms of rules-as-written, is this interpretation correct? Or do they need their formula book on hand during their daily preparations?