There are hundreds of crown ethers. I expect you used one of three: 18-crown-6, dibenzo-18-crown-6 or 15-crown-5. There are a lot of organic compounds. With such precise information you provide, you can only count on yourself.
Check the properties of your crown ether, compare with known or expected properties of the compound you synthesize and select the appropriate separation procedure.
And maybe all you can findin the procedure by which you conducted the synthesis.