Naproxen Sodium Standard

(S)-6-Methoxy-α-methyl-2-naphthaleneacetic Acid Sodium Salt; (S)-Naproxen Sodium Salt; 2-Naphthaleneacetic acid, 6-methoxy-α-methyl-, sodium salt, (S)-; (−)-Sodium (S)-6-methoxy-α-methyl-2-naphthaleneacetate (USP);