Compositions and methods for isolating L-glufosinate from a composition comprising L-glufosinate and glutamate are provided. The method comprises converting the glutamate to pyroglutamate followed by the isolation of L-glufosinate from the pyroglutamate and other components of the composition to obtain substantially purified L-glufosinate. The composition comprising L-glufosinate and glutamate is subjected to an elevated temperature for a sufficient time to allow for the conversion of glutamate to pyroglutamate, followed by the isolation of L-glufosinate from the pyroglutamate and other components of the composition to obtain substantially purified L-glufosinate. The glutamate alternatively may be converted to pyroglutamate by enzymatic conversion. The purified L-glufosinate is present in a final composition at a concentration of 90% or greater of the sum of L-glufosinate, glutamate, and pyroglutamate. In some embodiments, a portion of the glutamate in the starting composition may be separated from the L-glufosinate using a crystallization step. Solid forms of L-glufosinate materials, including crystalline L-glufosinate ammonium, are also described.L'invention concerne des compositions et des procédés d'isolement de L-glufosinate à partir d'une composition comprenant du L-glufosinate et du glutamate. Le procédé comprend la conversion du glutamate en pyroglutamate, suivie par l'isolement de L-glufosinate à partir du pyroglutamate et d'autres composants de la composition pour obtenir du L-glufosinate sensiblement purifié. La composition comprenant du L-glufosinate et du glutamate est soumise à une température élevée pendant un temps suffisant pour permettre la conversion de glutamate en pyroglutamate, suivie par l'isolement de L-glufosinate à partir du pyroglutamate et d'autres composants de la composition pour obtenir du L-glufosinate sensiblement purifié. Selon une autre possibilité, le glutamate peut être converti en pyroglutamate par conversion enzymatique. Le L-g
