check was made out to a gentleman personally, but deposited into his business account. the check was returned. can i take funds from both his business account and his personal account.

If the business is a sole proprietorship, you have a clear shot at both the business account and the personal account.

Based on endorsement warranties, you probably also have a shot at both accounts even if the business is not an SP. The gentleman, I assume, endorsed the check in his own name, and then the business endorsed it for deposit?

What's less clear to me is how you'd do this. If the check, say, is for $500, and each account (individual and business) has $250 in it, you'd have problem charging the full $500 to either account, and then using the theory of offset to replenish the overdraft from the other account. This would definitely be a problem if the account is not an SP, since no offset would exist.