Polkadot.js sr25519 secret key to hex

Question

I am creation a keypair using sr25519PairFromSeed. I am converting the public key from Uint8Array to hex using encodeAddress(publicKey, 0), but i have issues converting the secret key from Uint8array to hex. I use Buffer.from(secretKey).toString("hex") but the hex I recieve is invalid. I am doing the same thing but with ed25519 cypher and it works normally.

Thanks

I was expecting a valid hex string but i am recieving an invalid one.