Marie Madeleine D'Aubray, later Marquise de Brinvilliers, was executed in 1676. The Marquise de Brinvilliers was not involved in the Affair of the Poisons. The Marquise was tried before the High Court in Paris, not by the Chambre Ardente.
There also appears to be some confusion between a star chamber tribunal and the actual Chambre Ardente, which was established by Louis XIV in the spring (date is disputed) 1679. The Chambre Ardente was dissolved in 1682, as the Affair of the Poisons was buried.
A servant of the Marquise de Brivilliers did turn up tied to a poison ring which was tried by the Chambre Ardente at the end of its existence.
See: C.J.S. Thompson, Poisons and Poisoners (initially published in 1931, I have the 1993 Barnes and Noble reprint)pp. 177-188; Also, R. H. Robbins, Encyclopedia of Demonology and Witchcraft, Crown Publishers, New York, 1959, pp. 80-84.