Formaldehyde offgassing is a difficult issue to address. You have only two options: encapsulate or ventilate.
- To the extent that you can leave a few windows cracked for ventilation, do so, though it may take weeks or even months for the levels to drop below your sensitivity level.
- Or you can try to encapsulate.
You mention caulking or grouting so I'm not sure where you think your offgassing is coming from, but if it is issuing from a few cracks that you can caulk or grout and slow down the offgassing to a tolerable level, great. Do so. Any good caulk or grout will work.
If it is offgassing from new cabinets or cabinet finish, it is a more difficult problem that (if you can't wait til the offgassing slows on its own) can only be solved by refinishing the cabinets with a low- or no-VOC finish or removing the cabinets. I understand that bringing new items into your home can be very difficult if you're chemically sensitive and appreciate your problem.
There is nothing you can use to absorb the formaldehyde so if you can't live with it using ventilation, it must be encapsulate or removal. I wish there was better news.
For more information:
Read "What can I do to stop offgassing of chemicals used in mastic sealant in my condo's AC duct system?" a Q&A answered by Mary Cordaro.