The left-back has agreed personal terms and Barca have accepted an offer of €15m from Leeds.
Firpo is in England, though his medical will be held up due to the UK's arbitrary quarantine laws, reports Mundo Deportivo.
Leeds face an anxious wait for Firpo to take the medical, despite him now being in the city.
Sources inside Leeds admit there is no firm date for when the defender can complete his tests and his signing be rubberstamped. Once cleared, Firpo will sign a deal with the Yorkshire giants for 4-5 years.