Italian Leonardo Piepoli, one of seven riders to fail drug tests at the Tour de France, has demanded a counter-test, according to the French national anti-doping agency (AFLD).
During the Tour Ricco, the winner of two climbing stages, was ejected along with his Saunier Duval team after urine samples belonging to the Italian revealed traces of CERA.
Ricco followed Spanish duo Manuel Beltran, of Liquigas, and Barloworld rider Moises Duenas in leaving the race, both of whom tested positive for EPO.
On the race's final day it was revealed that Dmitri Fofonov, a Kazakh who rides for Credit Agricole, tested positive for a banned stimulant. He has since been banned for three months.
The AFLD recently pioneered a new blood test for CERA, notoriously difficult to detect, the latest generation of a drug which has been in use in endurance sports since the early 1990s.