Gunnar Werner, secretary of the international swimming federation, Fina, said that De Bruin's lawyer sent a fax to the governing body over the weekend asking for the B sample of her test to be examined.
De Bruin underwent an out-of-competition test on 10 January at her home in Kilkenny. Fina said that the A sample showed "unequivocal signs of adulteration", as it contained a lethal concentration of alcohol which could have been used to mask the presence of banned substances.
Werner said the backup sample will be opened and analysed later this week at the same IOC-accredited laboratory in Barcelona where the first specimen was tested.
If the finding is the same as the A sample, Fina will refer the case to its doping panel for a hearing in late June. "If it does not confirm the A sample, then the case is over with and De Bruin is cleared," Werner said.
The 28-year-old swimmer has denied tampering with her test and said any manipulation must have taken place after it was out of her sight.
De Bruin has been hounded by doping allegations since she unexpectedly won three gold medals at the 1996 Atlanta Olympics. Her husband and coach, the former Dutch discus thrower Erik de Bruin, was banned for four years after testing positive for high levels of testosterone.
Fina said that De Bruin could be punished by a four-year suspension, or even a lifetime ban, if found guilty, but she has stated her intention to fight the allegations all the way to the Court of Arbitration for Sport in Switzerland if necessary.Reuse content